PVA sizing

[Xandros]

Hi all,

An US gum printer told me he was using PVA sizing instead of gelatin to size the paper for gum prints. I'm in Europe and am not sure where I could find the same thing over here ...

http://www.dickblick.com/products/gamblin-pva-sizing/

Would you have any ideas by any chance ?

Thanks !

 

[pentaxuser]

Isn't PVA a substance used by woodworkers? If so then it should be easily available in Europe. Certainly is in the U.K. in Do It Yourself shops, builder's merchants and supermarkets such as Homebase B&Q BUT I'd check with the US gum printer to be sure his PVA is the same as the one I have just mentioned.

pentaxuser

 

[Rick A]

White Elmers school glue=PVA (poly vinyl acetate) adhesive.

 

[Xandros]

Thanks but the thing is that the PVA regular glue is not the same as the PVA sizing even though the base chemical is the same

 

[wildbillbugman]

PVA=poly vinyl ALCOHOL, NOT poly vinyl acetate The later is usually shortened toVAc. The acetate is NOT soluble in water.
There are many grades of PVA, as can be seen on DuPont's website for ELVANOL.I use Elvanol 70-30. It is one of the "fully hydrated" grades for maximum water solubility. A solution of this in water is crystal clear. Not white, like Elmer's glue. My source for it is thechemistrystore.com.
Bill

 

[Xandros]

Thanks Bill, so this Elvanol thing you're using is water soluble and then when applied on paper and dried, does not wash away when developing the print ? What's strange is that the US printer said the Gamblin thing had the consistency and color of milk.

 

[wildbillbugman]

This sounds like partially hydrolyzed PVA. Partially water soluble. With gum/dichromate printing, the OH groups on the PVA coating will react with the gum/dichromate and not wash off with in development. In fact, some people, including me, use PVA INSTEAD of gum arabic. It works.
Bill

 

[Xandros]

oh ok, and after several exposures does the PVA thing trap some dichromate, leaving the print a bit yellow and in deed of metabisulfite clearing like gelatin does ?

do you pre-size with something before using PVA instead of gum?

if only the exposed PVA does react and not wash off, this means that the white areas will wash off each time and the paper fibers will show through, leading to grey whites because no sizing, right ?... theres something confusing there.

 

[wildbillbugman]

Xandros,"
The PVA acts very much like gum arabic. It dose not "trap" the dichromate. I am not the originator of PVA instead of gum. I will try to find where I first read about it and refer you to that site.
Bill

 

[wildbillbugman]

www.hands-on-pictures.com/tutorials/gum

 

[Xandros]

thanks !

 

[wildbillbugman]

Also,one important thing I forgot to mention is that PVA, even fully hydrolyzed PVA, is not soluble in cold or look-warm water. To dissolve PVA requires HOT water.

 

[Xandros]

hmm the more I read about it the less I am sure its the same PVA at all

 

[Loris Medici]

Xandros, it's a question of finding the correct "CLEAR & WATERPROOF" PVAc glue. I use a local "Caparol" ("Filli Boya" here) PVA wood / paper glue, diluting it 1+4 or 1+5. It works like a charm!!! You don't have to import Gamblin stuff from the States... Just look for (again) a clear (when dried that is - I'm not talking about the glue in its original container...) and waterproof PVAc and try a couple or more products; one will certainly work. The first product I have tried worked for me - I guess I'm lucky! (BTW, Gamblin is PVAc to my knowing not PVAlcohol...)

Hope this helps,
Loris.

 

[R Shaffer]

I use the Gamblin PVA size diluted 1:1 on my gum-overs and gum prints. I like to use a coat after my third or forth layer of gum when my initial gelatine size has started to break down. I have not noticed any yellowing. The print does tend to develop rather quickly after a coat of PVA, so I need to watch it more carefully.

 

[Steve Smith]

PVA adhesive is commonly used diluted with water as a sealant. I have used it on plasterboard and it is often used on brick and concrete prior to subsequent coatings/finishes.


Steve.

 

[Xandros]

Thanks to all, I'll have a look at the local stores and post the info if I find something useful for the community BTW I found out it's possible to get the same exact Gamblin think from a UK-based online shop which imports it from the US.

 

[phritz phantom]

you do want the pv-acetate, not the pv-acohol! it being waterproof, is more or less the point of a size.

buying the gamblin product in europe is a complicated thing. the only source i know is, kremer pigmente in germany, who can special order it for you (i asked about it some time ago). and, irrc, someone in the uk sells it too.
you can try other pvac products you can find, but you have to test them yourself (a lot of research on that topic is yet to be done). i had mixed success (though unusable in the end) with the products from caparol and boesner.

 

[wildbillbugman]

Totally non-hydrated PVAcetate would be totally insoluble in water. You would need to dissolve them in an organic solvent in order to apply it to the base material. Then it would be totally impervious to aqueous solutions such as Pt/ammonium oxalate or gum/dichromate, I believe what you need is PARTIALY hydrolyzed PVAlcohol. DuPont makes many grades of this. These are milky emulsions in water, like Elmer's Glue.
For the subbing which I make for printing Pt/Pd/Au/Pigment on glass, and have described on an earlier thread on this Forum,, although I do start out with a totally hydrated PVAlcohol, I substitute silane groups for some of the hydroxyl groups. This makes the polymer less water soluble (but not insoluble) and promotes adhesion to glass.
Bill

 

[phritz phantom]

bill,
(judging from an earlier post of yours in this thread) i think you are speaking about alternatives to the gum arabic (which is possible with elmer's glue, i think i've heard before), but the OP asked about a SIZE and a size should be insoluble in water (hence the hardening of gelatine).