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ICG Bookcloth

<Subject:      ICG Bookcloth
To: Multiple recipients of list BOOK_ARTS-L

We use quite a bit of the ICG "D" grade, starch filled buckram and recently
reordered several hundred yards of it. ICG seems to have changed the
formulation for the cloth and it is no longer as nice to work as it once
was. The new batches seem much stiffer and don't take the moisture from the
glue as readily. We've also had adhesion problems with it, regardless of
whether we use the 50/50 mixture of PVA/Methylcellulose or straight PVA. In
some case we have had bubbles for several days-weeks after covering. We do
not have these problems with the old batches.

Anyone else have any insights on this?>

Although I am not  familiar with the ICG rang of materials, the problem you have
described does sound familiar.

On certain materials evaporation can not take place through the surface of the
cloth during the drying time, due to the particular finish, as is the case with
some buckrams.  Cloth on gluing/wetting  will contract, and on drying will
expand.  With these problematic materials, evaporation is more likely to take
place through the boards  resulting in the adhesive adhering  to the board and
not the cloths -  hence the bubbles.    In most circumstances, a higher starch
content in the material, will allow the cloth to absorb excess moisture which
alleviates any adhesion problems.  The wet starch  will also probably assist in
obtaining better adhesion.

There are several  possible solutions to the problem:

1. Reduce the amount of water content in your adhesive (or increase the % of
solids) - You may need to look for a PVA with a higher proportion of solids.

2. Reduce the thickness of the layer of adhesive applied to the cloth.  This may
sound contrary to 'gut' feelings, but by reducing the amount of adhesive
applied, you are reducing the amount of water that needs to evaporate.

3. An animal glue may solve the problem.  Although there is normally a high
proportions of water in animal glues, they are so tacky that they will just
stick to anything!

4. Persuade the producer of the cloth to revert to the old method of
manufacture!   :-)

I hope one of these solutions work.



David Lanning
J. Hewit & Sons - London

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