Sealing Raw Pine

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Ron Eggers

Ron Eggers

SPFG, Supreme Picture Framing God
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I may need to seal some clear raw pine. They aren't stretcher bars but the application is similar. There will be some textiles in direct contact with the wood. They're not artifacts, but anything worth framing is worth protecting, right?

I might need to do this regularly, so I'm looking for some convenience and I'd rather not destroy my few remaining brain cells.

Hugh mentioned water-base polyurethane in another context. Would this be a reasonable choice?

After I've done a little experimenting, I'll tell you what I'm working on and maybe post some pictures.

But I have to warn you - it involves the Attach-Ez. :eek:
 
Lacquer sanding sealer or shellac. I think for preservation purposes, shellac is the best choice. Both will definitely seal the wood. Several coats.

John
 
I would go with the polyurethane as pine has a lot of sap in it. I have (in my prior life) sealed pine wood plaques, and about two to three years later the pine sap started to seep out. Not a nice look. :eek: I wish I had used a hardier sealer.
 
You may also find that Pine in general is not Pine in particular. Not only can the average pitch content vary considerably from species to species, but also from tree to tree.

Then there is the fact of how it was dried. Pine that is sold specifically for use in furniture, if dried properly, will have a process at the end of the kiln cycle which will "set the pitch". This is a short-term high-heat process which crystalizes the pitch to keep it from interfering with finishes. While not always 100% successful, it is a help.

What I'm trying to say is, if you buy good quality material you will have less potential trouble. Hmmm... I wonder if I'm on to something there


PS: we don't sell Pine.
 
Ron,

I would use the water based poly- as it is odorless and dries fairly rapidly. One thing you may consider, pine is by nature a soft wood and water based poly- is a thin material, almost "water-like". You probably will have to do at least 2 coats with the first one completely dry before adding the second. This should seal the wood with the first coat and apply a consistent finish with the second.

I don't know of any finish that will stop pitch from oozing out over time though. If there are pitch pockets in the wood, not just the usual pitchy characteristic of pine but dark pockets of amber looking streaks, I wouldn't use it for any fabric mounting.

If you have some clear pine, this method should work just fine.

Framerguy

Edit: Those work tables you saw in my old shop were all finished in water based polyurethane.

[ 11-11-2003, 04:08 PM: Message edited by: Framerguy ]
 
I'd go with shellac myself. It drys fast and, being alcohol based, is relatively benign. We used it as a knot sealer in my trim carpenter days and it made a great base coat on pine trim Zinnser makes an spray can that is quick & easy.

Peter Bowe
Saline Picture Frame Co.
 
For sealing wood, CCI recommends 2 coats of water based urethane or acrylic (latex) paint. They also recommend that the sealed wood not be used for 6 weeks, to allow the urethane or paint to cure.

Shellac has its uses, but it is not a stable polymer - shellac yellows a lot as it ages, a sign that chemical reactions are occuring.

Rebecca
 
Six weeks, huh? That would take me right up to about Christmas. I guess I'd better get started.

Thanks, everyone, for the suggestions.
 
What level of preservation do you want?

For minimum preservation, don't bother to coat the wood -- leave it raw & let it deteriorate.

For moderate preservation, the low end would be shellac and other common painted finishes. The high end would be water-borne polyurethane such as Camger varnish, and ordinary plastic tapes such as 2" wide clear packing tape -- cheap & available from Sam's Club.

For maximum preservation, a gas-impermeable barrier is recommended. That would be either glass or metal. Glass doesn't wrap around surfaces very well, so metal tape probably would be the better choice. Try Lineco #387-0155 "foilback sealing tape". It's available in 1-1/4" x 500 ft. rolls from University Products and other Lineco distributors.

Painting the wood is cheaper in terms of material cost, but labor might offset the savings. Taping would be better for preservation if you cover the wood completely, or about as good as varnish if you just cover the contact surfaces. In any case, I suggest coating the wood in length, before you cut the miters.

And if time is an issue, taping would give you instant gratification - always a good thing.
 
I would say moderate preservation is what I'm after. The pine will not be visible, so appearance is not an issue, but it will be bevel cut and drilled, so I'd like to avoid tapes and foils.

I just picked up a can of MinWax water-base PolyAcrylic. It's a spray can, which I usually try to avoid, but it promises to be low odor and quick dry.

I'll give that a try.
 
Jim... I think you may have given Ron too much to think about! :D

Originally posted by Ron Eggers:
[QBI ...and I'd rather not destroy my few remaining brain cells.[/QB]
Click to expand...
Next time, just tell him to use the tape. Too many choices could hurt his brain. :D
 
Hi Jim -

I don't know what kind of clear packing tape you get in your area, but the stuff we buy at Office Depot etc. here couldn' be considered minimum preservation by any stretch of the imagination!

Oak Display Cabinets: Conservation Problems and Solutions
http://www.cci-icc.gc.ca/document-manager/view-document_e.cfm?Document_ID=80&ref=co

Guidelines for Selecting and Using Coatings
http://www.cci-icc.gc.ca/document-manager/view-document_e.cfm?Document_ID=333&ref=co

Display Materials: The Good, The Bad and The Ugly
http://www.cci-icc.gc.ca/document-manager/view-document_e.cfm?Document_ID=83&ref=co


Rebecca

[ 11-12-2003, 11:06 AM: Message edited by: Rebecca ]
 
Just read an article on this in Woodworker's Journal. Shellac and oil-based finishes including varnish, Danish oil, and polyurethane appear to be best for what you intend to do. The article also said that lacquer and waterbased coatings work better over a sealer. So you can use both if desire. For more info see Dec 2003 issue.
 
Thanks, Jim, and no offense, but do woodworkers know more about conservation framing practices than, say, artists typically do?

I gotta go with our Canadian conservator here.
 
No offense taken. No argument with her point, but a good sealer as a base coat will provide a better base when applying a waterbased sealer. It just provides a better surface to work from.
 
Ron asks..
Thanks, Jim, and no offense, but do woodworkers know more about conservation framing practices than, say, artists typically do?
Click to expand...
And I answer probably yes.

I defer to Rebecca - I sadly moved my shellac can to the back of the shelf after she gently dismissed it as I am in awe of her grasp of current research in materials and conservation issues.

Canadian textile conservators are a reliable group but... having worked with artists, framers and woodworkers the artists are often the ones most prone to holding tightly to misinformation. Most woodworkers would have given up on white pebble mat boards years ago.

"Is Your Contemporary Painting More Temporary than you Think?" is a great little book by an old school conservator who pretty much despairs of the practices every 20th century painter. (The Scream is painted on corrugated cardboard and curators have to sweep up debris in front of the Jackson Pollocks to cite just a few issues)

Artists are nice people and usually much more interesting than woodworkers at cocktail parties but I take their framing theories with a large grain of salt. Professional woodworkers are suprisingly aware of the physical and chemical properties of their materials. I subscribe to Art in America, Decor and Fine Woodworking. Of the three I find Fine Woodworking the most scholarly and the most well researched.


Peter Bowe
Saline Picture Frame Co.
 
My over-cute comment was misunderstood.

I meant that, unless woodworkers are considerably more knowledgeable than most artists about conservation framing, I'll stick with the conservators.

I fully understand that their are some artist/framers on The Grumble, but I believe you are the exceptions.
 
You all have been busy haven't you! ;)

I think Jim A has a good point - the shellac undercoat might well make a better working surface. It would dry/cure much faster than the waterbased urethane, and wouldn't raise the wood grain like water products do. And waterbased urethane over the shellac would seal it all up.

I'm basing my shellac thoughts on shellac varnishes on paper prints and also oil paintings that I've seen - over the years they turn a dark brown. Quite kudos-making when removed!

That's nice for you to say I know a lot, but really I don't. As I tell my teen aged daughter ad nauseum, it's not what you know, it's who you know. I happen to know some of the sources to go to to find out conservation type info, but everyone has their own area - that's where the "who you know" comes in.

If people are interested in varnishes and painting materials, a really good reference is

Rutherford J. Gettens and George L. Stout, Painting materials, A Short Encyclopedia (New York, 1966). I'm sure its still in print, and in paper back and it's one of the conservator's touchstones.

As far as Ron's application goes, whatever varnish/sealer he choses, I'd suggest stretching a sacrificial underlay of washed unbleached muslin under the actual textile.

Rebecca
 
Ironically, the application I'm working on would replace a previous one which used aluminum bar stock instead of pine.

Maybe I should just stick with the aluminum.
 
I find it extremely difficult to staple fabric art to aluminum bar stock. And, once I get the piece mounted, it immediately starts Galvanic action and turns the whole thing into a pictorial Van deGraf generator.

Very colorful when you approach the hanging art package! :D

FGII
 
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