Wood Frames, can acid contaminate Rag Mat board enough to affect the print?

[Borealis]

I'm going the old fashioned route framing my prints. It's all acid free material (mat, backer board, hinging tape etc)  but the wooden frames. My prints are almost all on rag paper as well. I'm wondering if it's worth the trouble to apply frame sealing tape around the rabbet. It's the glass that touches the rabbet for the most part but for sure the foam board and mat may also contact it a bit here and there... I do tell clients/people that the print will last for decades given proper display conditions.
William

[Paul Roark]

I have assumed that most of the acids the wood produces will vent out the back of an open frame.  Thus I leave the backs of mine open.  What makes no sense to me is to put Kraft paper on the back of an unsealed wood frame.  That would trap the acids.  I once challenged my local framer to find an acid free backing that would allow the acids out and not let the insects in.  He never produced such a product.

I recall reading a summary of a library conservation paper that basically found that old books that had lignin-containing paper in them, possibly in the cover, deteriorated 10 times faster if the books were sealed in bags.  Venting of the acids to the air is what we want to happen.

The wooden stretcher bars for canvas should probably be coated/sealed.  I wonder if those from our usual suppliers are.

Paul
www.PaulRoark.com

[Borealis]

Thanks Paul,
the wooden stretcher bars for canvas are another one in that line of thought. I guess the Kraft paper is mainly used to keep dust out, never thought that it could trap the acids.
William

[AlienAl]

I think it would take a very long time for it to affect the print, provided the back of the frame is not sealed off as Paul warns not to do.  But it just might contaminate the edges of the mat board to the point where you'll see a bit of yellow under the glass around the edges of the frame - and that might be, my guess, after five or ten years.  So it sounds fanatical, but you're probably doing a good thing to seal off the inside edges of the rabbet somehow.  I would suggest gluing - with acid-free PVC glue - narrow strips of a barrier paper like Permalife, which is a buffered paper if I remember right.  I think I'd leave the rear surface of the wood uncovered and unglued, however, to allow the acids to escape out the back way.  It's probably also better, n this respect, to use unfinished wood for your frames, rather than varnished or painted in any way.  I'd definitely avoid stains (mahogany, etc.), which are probably volatile unless very old.

Of course a framer could do all this (for a few dollars more, naturally), but very few customers are this conscientious or demanding (or have any idea what contamination means).
Allen

[pcgpcg]

  I think I'd leave the rear surface of the wood uncovered and unglued, however, to allow the acids to escape out the back way.  It's probably also better, n this respect, to use unfinished wood for your frames, rather than varnished or painted in any way.

I make my own frames and always apply a varnish to seal the wood. Otherwise it is highly susceptible to soiling and will be almost impossible to clean. I leave the back open and can't imagine that any outgassing from the varnish will be a problem as it will immediately dissipate.

[Borealis]

I also make my own frames and paint/varnish them. But leaving the back open can't be a long term solution for me either. I checked quite a few frames at friends houses and most of them did collect a surprising amount of dust on the back side. Somewhere I read that Kraft paper will not completely trap the vapors and lets them pass, but if this is actually true I don't know. I suppose I could just go ahead seal the rabbet with Lineco frame sealing tape and be pretty much done with it. It's not that I have a big production going on and the little cost or extra time may go a long way here.
William

[davidh202]

Lineco tape is just fine if you are that concerned about the rabbit seal!
The purpose of putting paper on the back has nothing to do with trapping or not trapping the possible out gassing of acids, but very much to do with keeping dust and mostly bugs out of the interior of the matting package. I have been a custom framer for over 30 years and have opened up so many old frames it isn't funny. I have yet to see negative effects of acid from the frame rabbit. What I see mostly is faded matting, which is evident when it is removed, because the area along the edge of the mat has not been exposed to light, and extremely rarely, yellowed at all due toacid from the frame rabbit. Acid free mats and backing will more than protect your photos.  Don't sweat the small stuff ;-) 
David   

[BobShaw]

What David said. Silverfish will eat your picture long before acid will yellow it.

[Borealis]

Thanks for the replies, and as David said I won't sweat the small stuff! His experience is all I needed to read about!
William

[Deardorff]

A lot depends on the wood and environmental factors. High humidity and heat, ozone and sulfur dioxide and other airborne contaminants all have an effect on this.

Aluminized mylar sealing of the rabbet coupled with using Bainbridge Alpharag Artcare board should give you the greatest protection.     http://www.lodimaarchivalmaterials.com/lam/Article.html

The link above gives some information on the mat board. Newer information is available if you search.

Newer mylar materials for dust seals are available and work well. Good framing practice is to occasionally open the frame for a check and 'tune up' to prevent deterioration and/or catch it before it progresses and harms the artwork.

[Borealis]

Thanks for the reply and link! Lots of good info.
William