Resolved Wipe On Poly and Preservation

[Kittyfaces]

Hi! Took a hiatus and haven’t posted in YEARS! Feels weird using the Grumble on an iPhone. Anyway, I’m sanding down the backs and rabbets of old frames to reduce friable material. Once that’s done, Ive been either applying foil tape to the frame or sealing the envelope to further ensure cleanness. I once read 3-coats of water based poly over wood is preservation grade. Could someone confirm that? I’d like to try a water-based wipe on poly cuz it sounds more economical than taping... not sure if wipe on is the same animal as traditional brush on when it comes to preservation. Thanks!

 

[wvframer]

Welcome back!

It does provide a seal, but I have read warnings that it is dependent upon there being no voids in the application of the polyurethane. This probably is what resulted in the 3 coats recommendation. Whether it is water-based or a wiping consistency should not make any difference.

The extra time it takes to sand, apply multiple coats and drying time usually eats up any financial savings from using foil tape. But, if you have lots of time and not a lot of money, it will do the job.

I have used it to stop the flaking of finish materials when working with older frames but still used tape once it was dry when I was concerned about preservation.

The PPFA Guidelines for Works on Paper recommends that nothing that is potentially harmful come within 1/8 inch of the art. So in theory, as long as there is a mat, and the edge of the art does not come within 1/8 inch of the edge of the mat, you can meet that standard without doing anything to the rabbet.

I still tape when it matters.

 

[Kittyfaces]

Awesome reply, thanks! I do have time and no money as Im starting back up, but... maybe “sticking”’with the tape is the way too go. It certainly kills two birds with one stone if I should tape either way.

 

[Jim Miller]

I once read 3-coats of water based poly over wood is preservation grade. Could someone confirm that? I’d like to try a water-based wipe on poly cuz it sounds more economical than taping... not sure if wipe on is the same animal as traditional brush on when it comes to preservation. Thanks!

Sorry, but I can't see how wiping would make a thorough coating. What you've heard about is Camger Polyurethane Varnish. and it was once considered the best way to seal rabbets. Yes, three coats would do the job, but it's not cheap, and taping with Lineco Rabbet Lining tape would be better for preservation, anyway.

 

[Prospero]

Why not form the inner 'sandwich' into a single unit by taping around the edges?
Then you need only brush the loose detritus from the rabbet.
It's quick to do and no messing about with foil tape or sealants. I always do it. It makes
assembly so much easier.

 

[Jim Miller]

Why not form the inner 'sandwich' into a single unit by taping around the edges?

If the only objective is to close the framing package to keep it clean, then taping works a treat.

Sealing the rabbet with polyurethane used to be considered a good way to prevent migration of acid and other chemical contaminants from the raw wood. However, closing the package with ordinary tape would not provide much value toward that preservation framing purpose. If that is the objective, we now have greater knowledge about preservation framing, and better methods and materials than the traditional coating with Camger Polyurethane varnish. That would still be better than ordinary taping with paper or plastic tape, but glass and metal are the only materials that provide an absolute barrier against chemical migration.

 

[Rick Hennen]

Sorry, but I can't see how wiping would make a thorough coating. What you've heard about is Camger Polyurethane Varnish. and it was once considered the best way to seal rabbets. Yes, three coats would do the job, but it's not cheap, and taping with Lineco Rabbet Lining tape would be better for preservation, anyway.

Camger has a product designated as 1-175 that has been used to seal out-gassing products in display cases for valuable documents. Last I checked it was still available.

 

[Jim Miller]

Camger has a product designated as 1-175 that has been used to seal out-gassing products in display cases for valuable documents. Last I checked it was still available.

That may be; it's been around for decades. Many conservation authorities still accept water-borne polyurethane varnish as a rabbet-sealing application, but it still does not provide a permanent gas-impermeable barrier, like glass or metal

 

[Kittyfaces]

Why not form the inner 'sandwich' into a single unit by taping around the edges?
Then you need only brush the loose detritus from the rabbet.
It's quick to do and no messing about with foil tape or sealants. I always do it. It makes
assembly so much easier.

Thanks for the reply! Yes, I did mention in my original post I’ve been sealing envelope. Think Im going to just stick with that.