Question Matting on Sheepskin

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k2500guy

CGF, Certified Grumble Framer
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I haven't been able to find any posts with this particular question so here goes. What kind of mats are acceptable for matting sheepskin. I normally use Crescent Select, would that be OK, or should I go to Rag.

Also, from what I've read animal skins prefer a slightly acidic environment. So what kind of backing board should I use? Rag also?

Thanks,
Bobby
 
Back to the OP - can you please share why you would feel that a buffered rag mat would have been any different than a buffered Crescent Select mat?

Seriously, as an educator - I am trying to understand the thought process that framers (and artists) go through when determining the suitablilty of materials.

As FramerDave suggested, one needs to be more concerned with the buffering agent than whether or not the board is made of cotton or alpha cellulose.

Again, what would a rag backing have/do that an alpha cellulose mat not do?

Why do you "normally" use Crescent Select? (I am not saying that there is or is not anything "wrong" with using Crescent Select) - I am trying to understand why the OP has determined that Crescent Select is his "normal" mat. What are the criteria that motivated you to make this decision?
 
The simple answer to your question is that unbuffered alpha cellulose boards would be preferred for framing the organic item.

For the purposes of preservation framing, alpha cellulose from cotton and from purified wood pulp are interchangeable.
 
Jim Miller said:
unbuffered alpha cellulose boards would be preferred for framing the organic item.
Click to expand...

Jim- Are you differentiating alpha cellulose boards from rag boards? If so, why isn't unbuffered rag appropriate for framing an organic item? Isn't cotton acceptable?

Can you be specific and give the product names/numbers of unbuffered boards that would be appropriate?

What if the colors that the unbuffered boards come in do not look good from an aesthetic standpoint?

What would happen to a diploma or document made of sheepskin if it were matted with a preservation board that is buffered with Calcium Carbonate? What if that mat and backing and filler board had zeolites? Would that be better?

How would a framer know what to look for if a sheepskin document came into their shop that was matted with an alphacellulose board (and you can tell because the inkjet number is still on the back and it has a colored face paper with a white core) - is there a "burn" like a paper object that was framed with a wood pulp mat?

Which is worse, lining the rabbet of a frame where the sheepskin document (even though matted) comes within 1" from the interior of the frame, but still using a mat that is buffered, or using a mat that is unbuffered and not lining the frame and the document comes almost to the edge of the mat? This is a serious question.
 
Wouldn't the unbuffered mat need to be just for the mats touching the sheepskin? So if the unbuffered board isn't in the proper color you would put your favorite Crescent Select, Crescent Rag, Bainbridge Apha or Rag, Artique...(yes there are a few more not mentioned that are equally as good....) on top of that for a pleasing design. Don't forget to use unbuffered board for behind the sheepskin as well.

Susan
 
susang said:
So if the unbuffered board isn't in the proper color you would put your favorite Crescent Select, Crescent Rag, Bainbridge Apha or Rag, Artique...(yes there are a few more not mentioned that are equally as good....) on top of that for a pleasing design.
Click to expand...

In the case of the OP, it would seem that what we are concerned with is the calcium carbonate or the buffering agent in a mat coming in contact with something it shouldn't. And a buffering agent makes an alkaline environment. So what we are fearful of is not an acidic situation, but the complete opposite.

If one cannot put a wood pulp mat on top of a rag mat and expect that the rag mat would act as an appropriate barrier to make a decorative mat acceptable from an acidic environment (or the migration of lignin through a rag or alpha cellulose barrier mat,) how is it any different for an alkaline situation? Wouldn't the calcium carbonate migrate through the unbuffered mat as well? Is an unbuffered mat an acceptable barrier for alkalinity?

Does alkalinity "outgas"? Would it "leak" out the bevel of the conservation board and make a "stain" around art as would an acidic mat lined with rag?

I am not poking fun at anyone but am trying to understand the logic here.

Why is it not acceptable to line an acidic mat (or even an "acid free" paper mat) with a conservation mat to protect the art but OK to line a buffered mat with a non buffered mat to protect the art from something that we know is harmful for it?

Wouldn't the buffering agent "escape" into the frame package and get to the sheepskin?
 
Rob Markoff said:
Jim- Are you differentiating alpha cellulose boards from rag boards? If so, why isn't unbuffered rag appropriate for framing an organic item? Isn't cotton acceptable?.
Click to expand...

It is ....

Jim Miller said:
For the purposes of preservation framing, alpha cellulose from cotton and from purified wood pulp are interchangeable.
Click to expand...
 
What kills me is that even the "Rag" mats have a buffering agent in them. That I am aware of there is only one or two from each manufacture that do not have the buffering agent added to the mat. So if you want to mat something, like a sheepskin, you better want white or cream. To my understanding it is only the materials that touch the object that would have to be unbuffered. You could put another mat on top of that that was buffered. Therefor the mat that touches the top and the backing both would have to be unbuffered. I just don't understand why they put the buffering agent in pure rag mats anyhow.
 
Thanks for the link RoboFramer. That is where my reasoning came from and it was reinforced in a class at WCAF in January by Paul McFarland when that very subject came up. The reference was to photos but wouldn't it apply to other things needing unbuffered board like a sheepskin?

"Remember that if the window mat does not touch the surface of the print, it doesn't matter what type of board is used. Acids and peroxides form volitiles readily, but the same does not seem to be true for calcium carbonate, which is used to buffer mat board. This means that the main concern is contact and not proximity. Since most of the board that is made today is laminated with polyvinyl acetate, the chalk in the board is needed to address the acetic acid that the PVA will eventually produce. Neutral papers and tissues are always safer to use, since they contain nothing but pure cellulose. If one wants to use a colored, buffered board and its window will touch the surface of the photo, a layer of unbuffered paper can be added between the mat and the photo to separate one from the other." Quote from Preservator
 
Susang- you East coasters beat me to the response. My thanks to Robo as well for bringing this 7 year old thread to the front.

The answer I was hoping someone would reply is : "Acids and peroxides form volitiles readily, but the same does not seem to be true for calcium carbonate, which is used to buffer mat board. This means that the main concern is contact and not proximity."

While saying one could just line a buffered mat with an unbuffered mat, it doesn't explain, "why" - and Hugh's response is what I was looking for.

Since there are probably a whole host of new people reading this forum today and many who may have not read the thread from 2004, I thought this point needed to be addressed in this thread.

I still would like a response to the questions of what long term contact with an alkaline mat "looks like." I know I have seen the effects of contact with an acidic lignin mat, but what should a framer look for that indicates improper contact with alkalinity?

I still need to know why Jim thinks that: "unbuffered alpha cellulose boards would be preferred for framing the organic item." Why are unbuffered alpha cellulose boards preferred over unbuffered rag?
 
Rob Markoff said:
I still need to know why Jim thinks that: "unbuffered alpha cellulose boards would be preferred for framing the organic item." Why are unbuffered alpha cellulose boards preferred over unbuffered rag?
Click to expand...

Let's assume that "rag" is taken to mean cotton fiber. Cotton fiber is pure cellulose and chemically speaking it doesn't matter if it comes from cotton bolls or from treated wood fiber. Cellulose is cellulose.
 
FramerDave said:
Let's assume that "rag" is taken to mean cotton fiber. Cotton fiber is pure cellulose and chemically speaking it doesn't matter if it comes from cotton bolls or from treated wood fiber. Cellulose is cellulose.
Click to expand...

Is there a difference between "alpha" cellulose and "cellulose"?

Dave- what do you mean that "it doesn't matter if it comes from cotton bolls or from untreated wood fiber." What is the "it" in it doesn't matter? Are there rag boards made from alpha cellulose too?

What are cotton bolls - or is it a typo and you mean cotton balls? I thought ragboards were made from cotton linters (Cotton linters are fine, silky fibers which adhere to the seeds of the cotton plant after ginning.)

I always thought that "alpha cellulose" boards were purified wood pulp and were called that to differentiate them from "rag". So if one referred to an "alpha cellulose" board it meant something like Bainbridge's Alpha Mat, Crescent Select, Artique, Peterboro's conservation boards, etc. A "rag" board usually meant it was made from cotton and not purified wood pulp. (Crescent Rag, Alpha Rag, Rising Rag, Peterboro Rag etc.)

Why did Jim specify "Alpha Cellulose" and not just say an unbuffered conservation/preservation grade board which would have included both types?
 
cotboll.jpg

Cotton boll

cottonball.jpg

Cotton ball


No, not a typo.
 
Thanks for clearing that up, Dave - I never saw those pictures or heard that term.

What about the rest of my questions? Is rag made from cotton bolls or linters? And the other ones as well.
 
"Alpha" Cellulose is wood pulp with the most acidic cellulose [Beta] (commonly
but wrongly referred to as "lignin"; which is the binding of walls of the cells)
removed. But because a self destructing acidic content is present, as well as an
attractant for acidic gases, a buffer (calcium carbonate = limestone, tufa, chalk,
marble etc with a pKa of 9.0) is used. This is viewed as a future guard against
possible acidification of the Alpha Cellulose or it's attracting said acidification.

In short, the use of buffering is to make the product slightly alkaline for a
"future" balance.

Cotton linter contains no acids, and therefore needs no buffering. Which
explains why pages in books from the 18th C are still in "good" shape, and
books with pages made from wood pulp (in common use since 1926) are
crumbling into a fine sand on the shelves of the Library of Congress.

But then, who cares... slap anything that the current "experts" deem correct
(by virtue of taking tours of vendor's mfg plants instead of scientific
research), because, "hey, in 50 years when it really matters, you'll be out of
business or dead anyway. Kick it down the road to your grandkids who don't
give a rip anyway.

Rob, as an educator you of all people should know, nobody is setting their
hair on fire over this issue, it's a "Master's" thing and agenda.

Otherwise they would be following what Hugh Phibbs shared 8 years ago.

Nothing has changed. Rag is Rag, wood pulp is wood pulp and calcium carbonate is still
alkaline enough to rip the glaze off a fine art photograph.
 
Rob Markoff said:
Is there a difference between "alpha" cellulose and "cellulose"?
Click to expand...
Alpha cellulose is the purest form of cellulose.

Why did Jim specify "Alpha Cellulose" and not just say an unbuffered conservation/preservation grade board which would have included both types?
Click to expand...
Because some framers erroneously believe that only cotton boards are "conservation/preservation grade", and that "alpha cellulose" refers only to purified wood pulp. But no. Alpha cellulose, the purest form of cellulose, can result from the processing of fibers of cotton, trees, jute, linen, and many other sources of cellulose.
 
"As Rebecca response suggests, this issue is quite complicated. Remember that if the window mat does not touch the surface of the print, it doesn't matter what type of board is used. Acids and peroxides form volitiles readily, but the same does not seem to be true for calcium carbonate, which is used to buffer mat board. This means that the main concern is contact and not proximity. Since most of the board that is made today is laminated with polyvinyl acetate, the chalk in the board is needed to address the acetic acid that the PVA will eventually produce. Neutral papers and tissues are always safer to use, since they contain nothing but pure cellulose. If one wants to use a colored, buffered board and its window will touch the surface of the photo, a layer of unbuffered paper can be added between the mat and the photo to separate one from the other. Chromogenic prints can be added to the list of candidates for unbuffered board that Wally and Rebecca have mentioned."

Hugh
 
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