Alternatives to Gesso for Water Gilding

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Patrick Okrasinski

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Patrick Okrasinski
I've been learning about watergilding frames for the past year, and have a question. I was wondering if there's anyone out there that has substituted rsg gesso with a different primer before using bole and watergilding a frame.

I find that most of the issues I've encountered when making frames have been from using gesso as a primer- it cracks at the mitered corners, applying with a brush it is very easy to encounter air bubbles, especially in parts of the frame profile where the gesso pools together and takes longer to dry, along a few other issues.

But what if I primed the wood with a water based primer (like bin 1-2-3) sanded up with a fine grit, then went to several layers of bole, sanded and polished before water gilding? Is the worst thing that could happen be that the bole doesn't properly adhere as well well to a water based primer as to gesso, but in that case the primer can still be sized with a rsg solution before adhering the bole? Does gesso serve any purpose other than filling the pores of the wood and creating a very smooth surface to which you can then apply bole and gild?

Is there any reason to believe that this will be a worse way to create a water gilded frame that will last over time?

I'm posting a frame I just finished, Initially I used a water based primer out of a spray can, and then a water based spray paint, and forgot about it for a while in my studio until I decided to just try to apply bole and water gild it and see how it comes out. Pretty happy overall, no signs of cracking at the miters. With all the issues I've been dealing with from using gesso, I'm wondering if its not possible to just forget about the gesso all together and use an alternative primer for the bole.


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I'll be following this with interest. Yes, I believe the rsg gesso is a better link to the bole but I'm not sure how a layer of rsg on top of the primer you're using, is it acrylic?, would hold up. I think someone recently talked about using bondo as a base so maybe alternatives could work? I've had good luck using Golden pva size to seal the wood instead of rsg but then use rsg gesso on top of that before the bole.
 
There was a discussion fairly recently. Little different, but maybe interesting to read up on?

www.thegrumble.com

Hide glue vs. RSG for Gesso

Eek!! I just switched from using rabbit skin glue to hide glue to make gesso. I have been water gilding for a few years now, and am uncomfortable with this new gesso! Hide glue has a bloom strength of 240, lower than the 400 bloom strength I was using. My recipe for hard gesso is 2:1:2...
www.thegrumble.com www.thegrumble.com
 
I have heard of people putting a layer of silk in the corners, with the gesso, to help with cracking. ( Same theory as drywall installers papering the seams. )
In the frame below, I chose to oil gild. I to had a cracking problem, ( mostly due to the nature of the wood, you will see a very slight crack at the inner portion of the frame ) till I did this. What I did on this frame, was mix Corner Weld ( Because of its flexibility ) with Durhams Rock Hard Water Putty, to make my base for the gilding. I also sealed it with a red automotive primer instead of Bole, as you can see, no cracks. The frame is about 20 years old.
Water gilding needs a much harder surface ( Reason for Bole and RSG ) in order to get the luster then the oil gilding process, which has a softer look.
I fully know this is not by any means a traditional method, ( I have been educated in the traditional methods by the way, such as the classes Marty taught ) but I like to experiment. Considering my back ground has been in research and development.
 

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It is probably better to analyse the physics of what happens when we water-gild. As you know already, the process relies on floating the gold leaf onto a wet surface and allowing the water to soak into that surface and so pull the leaf down flat. If that surface contains RSG, then the water re-activates the adhesive properties of the RSG and so holds the gold firm as it dries.
You can gild directly onto bare wood because the wood is porous enough to accept the RSG. Pre-Raphaelite framers used this for their oak frames, although the gilding was mostly oil-laid.
If we want a perfectly flat surface then we would use gesso to first fill the wood grain and further build up the surface independent of the wood. The chalk or whiting provides the material bulk required for this. RSG gesso is fully porous, so will soak up any water used in water-gilding.
If we now want a perfectly smooth surface, then we use a clay bole over the gesso. This has a much less build property and is only really useful for that final fine finish.
Because the bole, like gesso also contains RSG, it will stick best to a water porous surface. If painted over an artificial surface like acrylic or other, then you are taking the risk that there is sufficient adhesion in the RSG to hold it on to that substrate.
I wouldn't risk all that later work on such an uncertain foundation.
If you are having gesso problems then it most certainly down to the quality of the RSG you are using.
Only buy RSG from a reliable gilding supplies company. I use Manetti brand, if you can get it. It is a refined RSG and always gives me reliable results.
Cracking in the corners suggests too strong a gesso.
 
I know absolutely nothing about gessoing so this post may have no basis here but we do a large amount of woodworking at our shop. We use a water borne titanium pigmented lacquer as a primer. We find that it fills in voids and is incredibly easy to sand vs acrylics. We spent many years searching the various types of primers and settled on one called Acqualock sold by Vista Paints. I am not sure if they are a national company.
 
That's good to point that out and I'm sure the paint you describe does a superb job in filling the wood grain and as a primer for over-painting. But for water- gilding, we do need a water porous substrate.
Practically all water borne paints are based on an acrylic binder which will resist the absorption of gilding water.
 
Still figuring out how to use the forums, reply, etc., but I appreciate all the responses, they're very insightful! I'm leaning towards continuing experiment with other primers.

I have heard of using silk/linen in corners, but don't know enough about it to attempt it myself.

You can oil gild on top of almost anything, but then you're not able to burnish the gold, and I think leaf overlaps do not show on the final guilding? I would prefer to stay away from using oil sizes and their fumes.

It seems like the biggest concern is adhesion to an acrylic primer. When a primer is water based- does that mean it is not water porous? I'll look into the Aqualock, it seems like the spray primer I was using was some type of acrylic resin by the msds.

Obviously I wouldn't be water gilding on the primer, but on the bole on top of the primer. I did notice on this first frame that was essentially bole over acrylic, after applying the gilders water and leaf, it took much longer until I was able to burnish the gilding, so perhaps the water wasn't absorbed into all the underlying layers as fast as if if the was gesso underneath the bole.

Something I noticed is that bole seems much more robust than gesso. I use plastic spoons when mixing either RSG size or gesso or bole, and when the bole dries on a plastic spoon it is extremely hard to clean it off. Gesso cracks and breaks off with extreme ease. If there's such a great adhesion of the bole to literally a plastic spoon, maybe there isn't much cause to worry about using an acrylic primer? Also maybe this is something wrong with my gesso mixture in particular, but I know there's lots of research that's been done about RSG and gesso's poor longevity, since they're hygroscopic. In painting, using RSG to size stretched linen is guaranteed to create cracking, and almost all linens are now primed with PVA. I guess lots of people are really worried that modern acrylics/plastics might not hold up another hundred years...
 
Patrick Okrasinski said:
Still figuring out how to use the forums, reply, etc., but I appreciate all the responses, they're very insightful! I'm leaning towards continuing experiment with other primers.

I have heard of using silk/linen in corners, but don't know enough about it to attempt it myself.

You can oil gild on top of almost anything, but then you're not able to burnish the gold, and I think leaf overlaps do not show on the final guilding? I would prefer to stay away from using oil sizes and their fumes.

It seems like the biggest concern is adhesion to an acrylic primer. When a primer is water based- does that mean it is not water porous? I'll look into the Aqualock, it seems like the spray primer I was using was some type of acrylic resin by the msds.

Obviously I wouldn't be water gilding on the primer, but on the bole on top of the primer. I did notice on this first frame that was essentially bole over acrylic, after applying the gilders water and leaf, it took much longer until I was able to burnish the gilding, so perhaps the water wasn't absorbed into all the underlying layers as fast as if if the was gesso underneath the bole.

Something I noticed is that bole seems much more robust than gesso. I use plastic spoons when mixing either RSG size or gesso or bole, and when the bole dries on a plastic spoon it is extremely hard to clean it off. Gesso cracks and breaks off with extreme ease. If there's such a great adhesion of the bole to literally a plastic spoon, maybe there isn't much cause to worry about using an acrylic primer? Also maybe this is something wrong with my gesso mixture in particular, but I know there's lots of research that's been done about RSG and gesso's poor longevity, since they're hygroscopic. In painting, using RSG to size stretched linen is guaranteed to create cracking, and almost all linens are now primed with PVA. I guess lots of people are really worried that modern acrylics/plastics might not hold up another hundred years...
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If you want to give Aqualock a test run let me know. I would be happy to send you a small bottle. Please note that our use of this primer is entirely different from yours but after 30 plus years of doing this type of woodworking it is the best sanding primer we have found and so far every top coat we have tried has stuck very well.
 
You can of course go ahead and use whatever primer you like. If you can get the bole to stick to any of the artificial gesso's then that will be a little bit of a win for you.
But take a moment to reflect on why traditional frame makers have been using RSG gesso for centuries.
If you touch the surface of gesso with water, the gesso will not only suck up that water, but partially melt around that area. So, painting on wet bole causes the underlying gesso to melt slightly and so creates a 'welded' bond between the two materials.
You will appreciate that this does not happen with synthetic primers.
Given that the bole might superficially adhere to your primer, any water gilding will then rely on the gilding water evaporating from the bole and not being sucked down as with gesso. And then a further hazard arises when you try to burnish the gild. Rubbing down hard on the bole with the agate stone can easily cause the bole to flake off from the primer.
As I said previously, your problem is with the quality of the RSG you are using.
Try this -
Soak 30gm of RSG in 500ml water, and heat to melt.
Make gesso with 400gm whiting to 400ml RSG.
Add 2x teaspoon brandy and sieve gesso through a paint sieve ( you can buy paper disposable sieves on E bay )
Paint on one size coat, leave for 1/2 hour then slosh on as many further coats as you fancy.
 
vintage frames said:
You can of course go ahead and use whatever primer you like. If you can get the bole to stick to any of the artificial gesso's then that will be a little bit of a win for you.
But take a moment to reflect on why traditional frame makers have been using RSG gesso for centuries.
If you touch the surface of gesso with water, the gesso will not only suck up that water, but partially melt around that area. So, painting on wet bole causes the underlying gesso to melt slightly and so creates a 'welded' bond between the two materials.
You will appreciate that this does not happen with synthetic primers.
Given that the bole might superficially adhere to your primer, any water gilding will then rely on the gilding water evaporating from the bole and not being sucked down as with gesso. And then a further hazard arises when you try to burnish the gild. Rubbing down hard on the bole with the agate stone can easily cause the bole to flake off from the primer.
As I said previously, your problem is with the quality of the RSG you are using.
Try this -
Soak 30gm of RSG in 500ml water, and heat to melt.
Make gesso with 400gm whiting to 400ml RSG.
Add 2x teaspoon brandy and sieve gesso through a paint sieve ( you can buy paper disposable sieves on E bay )
Paint on one size coat, leave for 1/2 hour then slosh on as many further coats as you fancy.
Click to expand...
I know nothing of gilding so I'll be following this thread with enthusiasm. In just the last few minutes of reading, I've already learned a great deal. I had no idea how the process of water gilding worked, nor how it differed from oil gilding. Fascinating! one question - What's the brandy for?
 
It's for the alcohol in it.
Plus in you as well!! :beer:
 
I'm glad you are enjoying the subject.
There are a number of benefits to adding brandy to gesso -
The alcohol in brandy reduces the surface tension making it smoother to paint.
As gesso is painted on hot, the alcohol speeds up the cooling between coats, allowing the gesso to gel a bit before the next covering.
And the brandy has a pleasant smell.
 
vintage frames said:
I'm glad you are enjoying the subject.
There are a number of benefits to adding brandy to gesso -
The alcohol in brandy reduces the surface tension making it smoother to paint.
As gesso is painted on hot, the alcohol speeds up the cooling between coats, allowing the gesso to gel a bit before the next covering.
And the brandy has a pleasant smell.
Click to expand...
I agree with Matthew, this is all very fascinating. Thanks for the information.
 
Following this post with interest. Have you discovered anything yet? I am also wondering about synthetic alternatives for gesso. On that note, I am also trying to find out if it is possible to use water gilding techniques on synthetic surfaces such as different types of plastic (instead of wood, etc).

Thanks! :)
 
You can indeed buy synthetic gesso or you can make your own. Just mix diluted 50:50 PVA/water with whiting.
The boring bit comes when you try to sand it smooth. It will set like concrete.
That might be OK for a small area but not so clever when you might have a whole frame to work on.
Which brings me back to water-gilding on synthetic surfaces. Sorry but it's not going to happen. The reason is that the mechanism of water gilding relies on the goldleaf being allowed to float on to a small puddle of water and then being drawn down onto the frame surface as the water is sucked into the gesso. And if the gesso is synthetic - well that just doesn't happen because synthetic gesso is waterproof!
Of course you can oil gild on any surface. All you have to do is seal the surface if it's in any way porous and then apply an oil or Japan gold size.
Otherwise try to get friendly with RSG gesso. It's so much easier to work with. It has been used for centuries to make the most beautiful frames. Why would anyone want to use a plastic alternative?
 
I’m happy to read some of the news comments I’m the thread- I lost track of them.

vintage frames said:
I'm glad you are enjoying the subject.
There are a number of benefits to adding brandy to gesso -
The alcohol in brandy reduces the surface tension making it smoother to paint.
As gesso is painted on hot, the alcohol speeds up the cooling between coats, allowing the gesso to gel a bit before the next covering.
And the brandy has a pleasant smell.
Click to expand...

The brandy recipe is really interesting. I’ll try it and see how the gesso goes. This has been the most difficult part for me when learning to watergild.

As for why anyone might want to find an alternative for rabbit skin glue gesso- coming from the painting side, rabbit skin glue is notorious for not being archival- rabbit skin glue being used by artists to prime their canvases is one of the main causes in the cracking of paintings, and now a days many have switched to acrylics for that reason. I don’t know as much about conservation of frames as I do about paintings, but I haven’t seen many wooden and gesso gilded frames that haven’t cracked at the miters, and collecting frames from the 19th century it’s rare to find one where the gilding amd gesso hasn’t chipped. Artists friends say they are reluctant to send off water filter frames to juried exhibits and group shows because they’re much more fragile, and expensive, than cheaper frames. And in my own attempts, the gesso has been the most frustrating part of water gilding- perhaps if I had a pneumatic spray gun it would be a lot easier.

After a few months, the gilding and finish on the frame where I primed the wood with zinnser bullseye 123, and then applied bole and water gilding is fine, and no miter cracks either. I don’t know how well the primer will do on a synthetic surface, but it would be interesting to experiment with framing styles using tech like 3d printing, it might open a whole new opportunity for design as well as being archival.
 
Sorry to hear that gesso can be still a problem. I'll be repeating myself when I say that 99% of the problem is due to poor quality RSG. Next reason is making too strong a solution of RSG and hence too strong and brittle a layer of gesso. See what I've said in previous posts. Gesso cracking in the mitres is caused by wood shrinkage and that is usually because the gesso is too strong. You'd be amazed by the force a coat of gesso will exhibit on a wooden frame. You already see this on poorly coated canvas.
For large runs of gessoing I also use a spray gun. It doesn't affect the finish but speeds up production. Two coats from the spray gun are all it takes to get a good coverage, whereas painting it on can take 4 or 5 coats. Whatever method you use it's important to brush on the first coat and leave for 1/2 hour before continuing.
 
vintage frames said:
Sorry to hear that gesso can be still a problem. I'll be repeating myself when I say that 99% of the problem is due to poor quality RSG. Next reason is making too strong a solution of RSG and hence too strong and brittle a layer of gesso. See what I've said in previous posts. Gesso cracking in the mitres is caused by wood shrinkage and that is usually because the gesso is too strong. You'd be amazed by the force a coat of gesso will exhibit on a wooden frame. You already see this on poorly coated canvas.
For large runs of gessoing I also use a spray gun. It doesn't affect the finish but speeds up production. Two coats from the spray gun are all it takes to get a good coverage, whereas painting it on can take 4 or 5 coats. Whatever method you use it's important to brush on the first coat and leave for 1/2 hour before continuing.
Click to expand...
The recipe I’ve been using called for 50grs per 500ml of water… go figure. I really appreciate the explanation, now I know exactly what to fix. I’m going to try to follow your instructions to a T and see how it goes!
 
Patrick Okrasinski said:
As for why anyone might want to find an alternative for rabbit skin glue gesso- coming from the painting side, rabbit skin glue is notorious for not being archival- rabbit skin glue being used by artists to prime their canvases is one of the main causes in the cracking of paintings, and now a days many have switched to acrylics for that reason.
Click to expand...
I would take issue with that theory. The reason oil paints crack is that they go on curing for decades (centuries?). They will develop the familiar 'craquelure' to a greater or lesser extent according to the way the artist mixes his paint. It has nothing to do with the RSG in the primer. There are artefacts made using RSG that go back to the ancient Egyptians. How much more archival can you get? 🙂


** Acrylics on the other hand are a modern innovation so nobody knows how they will last in the looooooooooooong term. 😕
 
Patrick Okrasinski said:
…After a few months, the gilding and finish on the frame where I primed the wood with zinnser bullseye 123, and then applied bole and water gilding is fine, and no miter cracks either. I don’t know how well the primer will do on a synthetic surface, but it would be interesting to experiment with framing styles using tech like 3d printing, it might open a whole new opportunity for design as well as being archival.
Click to expand...

It’s funny you mention 3d printing because that’s exactly what I’m dealing with.

Additionally, I use Zinsser BIN shellac-based primer on everything from plaster to 3d printed materials before painting and it seems to work really well. I haven’t tried the 123 primer though. For the frame you primed with zinsser, did you add gesso before water gilding? Curious to see how it goes!
 
There have been various products over the years that claim to allow you to do water gilding the easy way.

They are all OK to a point but also all trying to re-invent the wheel. 🙄
 
Prospero said:
I would take issue with that theory. The reason oil paints crack is that they go on curing for decades (centuries?). They will develop the familiar 'craquelure' to a greater or lesser extent according to the way the artist mixes his paint. It has nothing to do with the RSG in the primer. There are artefacts made using RSG that go back to the ancient Egyptians. How much more archival can you get? 🙂


** Acrylics on the other hand are a modern innovation so nobody knows how they will last in the looooooooooooong term. 😕
Click to expand...
Well there are a few reasons why paintings crack, sometimes its the cause of medium (waxes, driers), layering paint layers, varnishing with damar, or even using pigments like zinc or bitumen- but my understanding is the issue with rabbit skin glue is that it is hygroscopic and it can be a compounding issue on a stretched canvas. On a stretched canvas as the humidity & moisture changes, the stretched canvases absorbs moisture through the back. In different seasons the linen will sag and droop, or be as tight as a drum. Over time it can cause a particular type of cracking to a painting, not necessarily the craquelure though.

RSG might be a great way to size a wooden panels though, I've seen very old paintings done on panel where the surface is immaculately preserved. But I've also seen them where there is an awful amount of warp in the panel- ultimately wood is not too stable either.

I don't know what rsg artifacts go back to Egypt, but to my knowledge artist have only been stretching canvases for a couple hundred years. There are some well preserved examples of paintings on linen, but unless they're well taken care of and often conserved, rsg has not been a great recipe for durable paintings.

I agree about acrylics, there were definitely some bad recipes in the mid century. Who knows. I'm told if you really want your paintings to last, paint a painting in a single session on a metal panel.
ZiaDaugherty said:
It’s funny you mention 3d printing because that’s exactly what I’m dealing with.

Additionally, I use Zinsser BIN shellac-based primer on everything from plaster to 3d printed materials before painting and it seems to work really well. I haven’t tried the 123 primer though. For the frame you primed with zinsser, did you add gesso before water gilding? Curious to see how it goes!
Click to expand...

Well these are just my experiments and I am not a master gilder. I have tried tried using gesso on the 123 primer, and it bonds stronger to the 123 than the 123 does to the wood, which I know because I've had some mishaps where I ended up striping the gesso and primer from the wood, because after applying the gesso I had all sort of cracking and air pockets forming, but that's on me being inexperienced and trying to apply a bad recipe of gesso onto wood with a brush. I've had some frames come out fine with the 123, gesso, bole, gilding. The 123 seems pretty fool proof and you can but it in a pint or even spray can. Sands pretty well too, and I don't know whether water polishing gesso gets a much better surface than working up to a 1200 grit sandpaper on the 123. I've also used Charbonnel Bole right over the 123, and it was fine. Maybe it took a little longer until the water evaporated and it was hard to where I could burnish it, compared to bole over gesso, but the gilding came out fine in the end.

I've never tried the Kolner thing, but real bole has been easy to use and apply imo.

vintage frames said:
Let's put it this way,
RSG is very cheap. Whiting is very cheap. Clay bole is reasonably cheap. Apart from gold, that's all you need.
I shall remain silent about Kolner products.
Click to expand...

Maybe the other important thing missing in that recipe is a little bit of know how- the one thing about trying the primer substitute for the gesso is that it felt idiot proof, whereas I've struggled a lot with gesso- from measuring out the right proportion of rsg to water, and then to gesso, to having a double boiler at the right temperature, to proper application technique to waiting the right amount of time before it dries but not too long to re-coat. The 123 you can spray from a store bought spray can, or paint it, sand, and then get to straight to the bole, which for whatever reason has been easier for me. I am still learning, and will be trying out your suggestions from earlier in the thread- I deeply appreciate the input!
 
Gilding is really only about making gold stick to a frame or whatever. There are loads of ways of doing it.

The real art comes from what you can do when you've got the gold stuck down.

Do your gilding whatever way you want, then go to a public art gallery; look at the gilding on some of the early frames there and think - "does mine look as good as that?"
 
I agree about the hygroscopic properties of RSG. We've all seen frames that have hung quite happily for
centuries on a wall, only to be taken down and stored somewhere on a concrete floor or some such place.
Within weeks the gesso will crumble to dust. Same applies to an extent with paintings. The thing is not to put
gesso'd items in a damp environment. 🙂
 
Hi, Concerning water gilding and rsg, rabbit skin glue is the standard protein binder to use for this method as it’s strong but flexible. It’s also the binding component in the gesso so I would recommend staying with it. There are ways to address the cracking of gesso in the mitres by using a piece of fabric or Japanese paper, usually though on flat sections of moulding. After that it really comes down to brush technique and keeping those corners thin and tight with the gesso , watching out for pooling.

Pinholes come from air bubbles which can be aggravated by environmental heat and low humidity and other factors but they too can be largely controlled and oftentimes eliminated by technique which includes care in preparing the materials, watching that the gesso isn’t heated too long or passed 120F, and using your hands during the gessoing in smoothing out the gesso during its application for the first few and then the final coat.

I know this can be initially frustrating to deal with but once you get these things under control then the process becomes second nature like so many other things. I just started an online class where we’ll be addressing these very aspects, all usual things to encounter in water gilding so you’re not alone :).
 
By the way, I’m new here! After hearing about this site for a long time and seeing some great questions on gilding I thought it was time to join in. I’ve been immersed in gilding for these last 40 years and always happy to share my 2 cents :). Some great talents here I can see!
 
Pin holes in gesso!
Nothing to do with air bubbles, how you mix it nor how you paint it on.
Pin holes are the result of the substrate, wood, absorbing and pulling the water out of the wet gesso before it has a chance to gel.
For example, try painting some fresh gesso onto a layer of already dried gesso. After drying the top layer is like a crunchy honeycomb of pin holes.
Here the actively hydroscopic underlayer of gesso has sucked out all the water from the top wet gesso leaving behind a latticework of pin holes. Think of a cube of very wet sponge sitting on the wood. It's almost a solid object.
Now squeeze out the sponge and you have a light object full of holes.

To avoid pin holes - paint on two initial coats of gesso. Let them dry for about15min then go ahead and layer up all the next coats. The first two coats will have sealed the surface of the wood and tempered it ability to absorb the water from the gesso.
 
Gildingstudio said:
By the way, I’m new here! After hearing about this site for a long time and seeing some great questions on gilding I thought it was time to join in. I’ve been immersed in gilding for these last 40 years and always happy to share my 2 cents :). Some great talents here I can see!
Click to expand...
Welcome to the G! I am sure your expertise will be very much appreciated. I love reading about this, I have never gilded anything but I do love learning more about it.
 
Ylva said:
Welcome to the G! I am sure your expertise will be very much appreciated. I love reading about this, I have never gilded anything but I do love learning more about it.
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Thanks so much! Gilding is certainly a fascinating field and interesting to explore the historical materials and approaches like gilding with garlic juice :).
 
Vintage Frames said:
Pin holes in gesso!
Nothing to do with air bubbles, how you mix it nor how you paint it on.
Pin holes are the result of the substrate, wood, absorbing and pulling the water out of the wet gesso before it has a chance to gel.
For example, try painting some fresh gesso onto a layer of already dried gesso. After drying the top layer is like a crunchy honeycomb of pin holes.
Here the actively hydroscopic underlayer of gesso has sucked out all the water from the top wet gesso leaving behind a latticework of pin holes. Think of a cube of very wet sponge sitting on the wood. It's almost a solid object.
Now squeeze out the sponge and you have a light object full of holes.

To avoid pin holes - paint on two initial coats of gesso. Let them dry for about15min then go ahead and layer up all the next coats. The first two coats will have sealed the surface of the wood and tempered it ability to absorb the water from the gesso.
Click to expand...
Well, it actually has a lot to do with air bubbles. And how the gesso is prepared is very important so I really have to disagree with you here. Pinholing does occur from different situations as well, I agree, but they are indeed related to air bubbles which is why gilders work to minimize or eradicate them. The environmental relative humidity and heat can affect this as well, which is why gessoing on a hot August afternoon isn’t the greatest. The architecture of the moulding appears to play a role as well.
 
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Vintage Frames said:
It is probably better to analyse the physics of what happens when we water-gild. As you know already, the process relies on floating the gold leaf onto a wet surface and allowing the water to soak into that surface and so pull the leaf down flat. If that surface contains RSG, then the water re-activates the adhesive properties of the RSG and so holds the gold firm as it dries.
You can gild directly onto bare wood because the wood is porous enough to accept the RSG. Pre-Raphaelite framers used this for their oak frames, although the gilding was mostly oil-laid.
If we want a perfectly flat surface then we would use gesso to first fill the wood grain and further build up the surface independent of the wood. The chalk or whiting provides the material bulk required for this. RSG gesso is fully porous, so will soak up any water used in water-gilding.
If we now want a perfectly smooth surface, then we use a clay bole over the gesso. This has a much less build property and is only really useful for that final fine finish.
Because the bole, like gesso also contains RSG, it will stick best to a water porous surface. If painted over an artificial surface like acrylic or other, then you are taking the risk that there is sufficient adhesion in the RSG to hold it on to that substrate.
I wouldn't risk all that later work on such an uncertain foundation.
If you are having gesso problems then it most certainly down to the quality of the RSG you are using.
Only buy RSG from a reliable gilding supplies company. I use Manetti brand, if you can get it. It is a refined RSG and always gives me reliable results.
Cracking in the corners suggests too strong a gesso.
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Good info here Vintage although I have a different view on the strength of the rsg causing the cracks at the mitre which I find to be more technique than anything. If the rsg was too strong as you suggested in Alice’s mitre problem then crack mechanisms would likely be happening elsewhere on the gessoed surface, which she didn’t indicate. Gesso in water gilding often cracks along areas of Joins once rehydrated, whether from a frame buildup or mitre or even over a deep wood grain occurance. It’s the nature of it. So the fabric or Mulberry paper can help minimize or prevent that from happening when the bole is hydrated before leafing.

Alice from Sweden also didn’t say what the strength of her glue was so we don’t know if it was too strong or not. Your recipe is good, it’s nearly equal to my hard gesso but I then follow with a soft gesso which has twice the whiting as hard, an old English recipe. I still hold that if the cracking is at the mitres only then likely it’s technique of a little too much gesso in the corner where it’s drying quicker on the outside than the inner portion.
 
Hi Vintage Frames, Greetings from this side of the water…Hard and Soft refers to the relationship between the rsg and whiting (once the water evaporates that’s what we have left). It’s meant as a very stable way of building up gesso resulting in a nice burnish, good adhesion and better sandability. It was passed on to me over 30 years ago by a teacher who had studied in England. When I later worked at a high end frame shop I noticed they used the same one. As it turned out it’s the approach recommended by one of the papers included in the book Gilded Wood: Conservation and History. It came out of the Gilding Conservation Symposium at the Philadelphia Museum of Art (an excellent reference book!). You’d like it if you don’t have it.

Anyway, I have used this recipe for decades on all of my work. it starts with a 10% rsg solution (1 rsg : 9 water) . Additional water is then used after the glue is made. The ratio of rsg to additional water to whiting is 2:1:2 for the Hard and 1:1:2 for the Soft (twice as much whiting for the soft). The hard needs to go down first always or else it’ll delaminate.

Particle size of the whiting and bloom strength of the glue all of course play their roles in the response of the gesso but the recipe has been very dependable over the years. I still enjoy exploring the different fillers to compare, carb, sulphate…
 
I can now understand what you mean by hard and soft gesso. Yes, that's a good way of dealing with the problem of potential cracking when creating a high build with your gesso.
I have found that using a spray gun to apply the gesso gives a much more reliable finish and provided the RSG is made to the correct strength, I can achieve a high build in a fraction of the time it would otherwise take with a brush. And of course, the spraying comes into its own when there is a large quantity of frames to gesso.
For general work, two coats with the spray gun will give sufficent build to allow for all the sanding required for a faultless finish.
 
It’s been a stable recipe over the years and very reliable, need to keep the strength in the right place as you say. Some folks use the guns here too and very quick, great for production. I’ve always just liked the hand approach though, perfecting the hand technique. I think spraying would feel too much like a job to me LOL - but yes, it’s an all day affair! :) I imagine you’re getting a decent burnish with the hard gesso? I originally made it like Stanley Robinson by eyeing the whiting quantity like a falling mountain but later switched to Metric which is much more exacting.
 
ZiaDaugherty said:
Following this post with interest. Have you discovered anything yet? I am also wondering about synthetic alternatives for gesso. On that note, I am also trying to find out if it is possible to use water gilding techniques on synthetic surfaces such as different types of plastic (instead of wood, etc).

Thanks! :)
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Yes, I water gild on plastic. I was trained in glass gilding, but in certain circumstances glass isn't viable so I've used clear acrylic panels and plexiglass. The beautiful quality of the glass is lost, but the gilding is still mirror-like. I'm skeptical of some of these claims that say a porous surface is required for water gilding since obviously glass is not porous, but maybe there is another scientific property at work here that sucks the gold to the glass. This week I'm going to experiment with gilding onto polyurethane coated wood. I know, sacrilegious! I know it is unlikely to be mirror-like, but you can't know if it will look cool until you try.
 
You can use clear shellac varnish which your gilding supplier should stock. Apply it diluted with meths and with a soft sable mix brush. Alternatively use a coat of RSG which will suit the matt gilding. I actually use the same RSG over burnished gold. The gilding will still shine through and doesn't look so brittle.
 
Vintage Frames said:
You can use clear shellac varnish which your gilding supplier should stock. Apply it diluted with meths and with a soft sable mix brush. Alternatively use a coat of RSG which will suit the matt gilding. I actually use the same RSG over burnished gold. The gilding will still shine through and doesn't look so brittle.
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What is meths and what does RSG stand for?
 
I’ve read this thread with interest and my general comment is that the beauty of water gilding, for me, is in the magic of the traditional materials, the knitting of the layers, and how the gold adheres beautifully to the coating of bole. I am not sure if you can replicate the beauty of water gilding with other, or modern, materials but perhaps? You and others commenting above seem to be getting great results.

Following on the question on how to reduce the gesso cracking above the mitre corner: in the fourth comment David Hewitt mentioned using a layer of silk in the corners with the gesso. The Italian term for this layer is the intelaggio and it is put on after the initial size, and before the gesso is applied. You should use a very soft, thin, washed, close-weave fabric for this. Soak it in the rabbit skin glue, press it over the join, and then allow it to dry fully before applying the gesso. I like fine silk but some gilders use long fibred Japanese tissue like that used for hinging. If you use Japanese tissue make sure that the grain is perpendicular to the join. If you are using silk you can tear it into thin strips, but if the area you want to cover is very curvy cut your strip on the bias so it conforms more easily to the shape. I recommend Practical Gilding by Peter and Ann MacTaggart for a very good description of the intelaggio preparation and application.

Also, a positive note on the Kölner system: while I have not used it to fully gild frames it has a place in frame conservation and restoration, and especially for small areas of repair. It is worth having in a repair kit, in addition to watercolour paints and mica watercolours.
 
The corner cracking issue is mainly due to wood shrinkage. Wood will always shrink transversely.
It's a good idea to let the chopped rails ;normalise in a dry environment for a few days before joining,
especially if it's been stored in an unheated place in a cold climate.
**A 4" wide plank of untreated pine will vary about 1/8" between summer and winter in my neck of the woods.
My shed door sticks in winter as well. 🙄
 
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