Adhesives. A general discussion.

[Jacob]

In the past I have used a number of adhesives to attach paintings on panel to a variety of surfaces where a frame is not desired. I've never had a problem, but every time I do it, my adhesive paranoia comes out anyway. To clarify: I hate hanging anything without mechanical support. I also hate doing anything that is irreversible. Sometimes however, due to the customer's restrictions or needs or insistance, there's no way around it.

Because of the recommendations I've read in the archives here and other sources, this time I decided to use Gorilla Glue as my adhesive of choice. Aside from the drawback of its expansion properties, I'd have to say it lives up to its reputation as being incredibly strong. I'm pretty sure I would snap the panel or the support before the bond gave way. Thumbs up to the Gorilla guys.

Since adhesives seem to be a pretty common hurdle to framers (and a lot of folks here have a problem with cutesy titles for threads) I thought perhaps a straightforward topic discussing your adhesive preferences and what you use them for would be in order. Mostly I'm talking about adhesives for heavier pieces, not paper as much. But whatever you want to share I'm sure that I and many others would be interested in hearing. Believe me, there are adhesive jobs that I did when I first got started, where I wished I didn't have to reinvent the wheel.

So if you want, please share your thoughts and experiences about your favorite adhesives (or your not so favorite adhesives), what you use them for, and your thoughts on the archival quality issues (if any).

Thanks.

 

[wpfay]

It has been recommended to me that in order to insure reverisbility when bonding wooden objects, or repairing same that I use rabbit skin glue, more commonly marketed as Hyde Glue.

I guess the issue of permanence and strength are arguable, but does the glue really have to outlast the pigment? Other issues when mounting panels may be more imprtant than what glue you use. For instance, if the support structure doesn't have the same degree of reaction to changes in the environment (temperature and humidity) it could lead to shear stress between the panel and the support resulting in warping.

One of my personal favorite glues is Mighty Muck. Also sold by different names from different suppliers, it is basically a PVA glue that is heat reactivated. It remains flexible when dry, and I've used it at one point to join frames, though it's intended use is in mounting fabric to board or liner stock.
One frame I joined with it was about 3/4" x 1 1/2" in profile. I put the frame together and waited about 2 weeks before proceeding. Of course I made the frame the wrong size, so after carefully extracting the v-nails, I tried to break the glue joint. Couldn't do it without breaking the frame...ended up sawing the joints apart.

 

[Rebecca]

Some random generalities:

The problem with hide glues is that the bond can pop if it is in too dry an environment (central heating). Sometimes alum is added to the glue to "harden" it; hardened hide glues do not resolublize.

For bonds with non-pourous materials, like glass or hard fired porcelain, epoxys are good. They come in various viscosities. The thin ones can wick into pre-clamped joins; thick one's like 5 minute stay where you put them, there are also epoxy putties, that act as fillers as well as adhesives.

Emulsions (acrylic or PVA - poly vinyl acetate) are water based, and the adhesive cannot be resolubilized after they have dried, though they can be softened somewhat with polar solvents like acetone and ethanol. They have a high concentration of adhesive molecule to solvent (water) and so can be very strong, depending on how the molecule is engineered, and also what additives are included).

For irreversible bonds with semi porous surfaces (like wood to wood) the PVA emulsions, like carpenter's glue, are very good. Strength depends on the type and concentration of the molecule and/oir additives- carpenter's glue would be stronger than "school glue", but they are both PVAs.

Acrylic emusions are typically weaker than PVA emusions. Many acrylic emuslions can be heat activated after they are dried (and I guess some PVA emulsions too if, as Wally says, Mighty Muck is a PVA); it depends on how the molecule is engineered and/or additives. The strength of the bond will depend on the particular type of emulsion.

There are Ethylene Vinyl Acetate emuslions too, but I don't know much about them. They are sometimes used in textile conservation, mainly by those trained in England.

There are PVA and Acrylic resin adhesives too. Acryloid B72 is "methyl methacrylate etc. etc." , often used for varnishing paintings and also as an adhesive,usually in paintings conservation. They are not as strong as the emuslsions, as they are not as concentrated, but they do, theoretically, remain reversible in solvent. Their chemical structures can change over time, though B72 is thought to be one of the most stable of the acrylic resins.

Beva is an ethylene vinyl acetate (EVA) resin adhesive (hence the name, with the B for Berger, the guy who developed it). EVA's themselves aren't that strong, so Beva has additives to make it stronger and more flexible. It's used for lining paintings and also bonding fabric to fabic, or fabric to wood, metal etc. There is also an emuslion available, though I've never used it. Beva softens with heat, and is resolublized with non-polar solvents like xylene.

You didn't want paper adhesives, so won't go into wheat starch paste or methylcellulose or gums, or the Lascaux acrylic emulsions...

Rebecca

 

[Rebecca]

Too late to edit above, but just wanted to add:

The trouble with propritary adhesives, like Gorilla Glue, is that we don't know what they are, so can't predict how they will behave over time. Even if they are analzyed to find out major ingredients, the formula can change without notice.

Rebecca

 

[Dave]

Thank you, Rebecca, for your always valuable expertise and taking the time to so succinctly respond to Jacob's request. You're a large part of what makes this forum such a beneficial resource to all framers.

Dave Makielski