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Diluting PVA 75/25 for Canvas to Foamboard

Posted: Wed 20 Jan, 2010 2:33 pm
by Bagel Framer
Hi all,

I find myself with a "minor canvas crisis" in that a Canvas I did for a customer/friend has gained air bubbles (said canvas is above their daughter's cot and is lit by spotlights - whether that's caused the bubbling or not who can say).

Trawling through all the posts re. PVA and canvas shows that I should dilute PVA with water to the ratio of 75/25 respectively to make it thicker, coat both surfaces, wait for it to go tacky then roll out the canvas and work from the middle outwards to counter any air bubbles then weigh the package down. Will this really work, as I would have thought adding water to already thick PVA will make it thinner?

My previous attempt at bonding was to roller straight PVA out onto the foamboard, wait for it to go tacky then smooth out the canvas - I then put three sheets of 36" x 24" glass over it which covered the canvas comfortably.

I believe this is "last chance saloon" alternatively I can take it to a framer who has an Hot Press, but I'd dearly like to crack it myself...!

Unfortunately I can't staple it to stretcher bars as the image is already cut to size and has no scrap around it.

Sean

Re: Diluting PVA 75/25 for Canvas to Foamboard

Posted: Wed 20 Jan, 2010 5:04 pm
by JFeig
Bagel Framer wrote:I believe this is "last chance saloon" alternatively I can take it to a framer who has an Hot Press, but I'd dearly like to crack it myself...!
Actually this is your best alternative before any other suggestions are tried. Heat will reactivate the PVA. I would suggest heating to 150°F (65°C) and let cool to room temp under the pressure of the press.

Re: Diluting PVA 75/25 for Canvas to Foamboard

Posted: Wed 20 Jan, 2010 7:30 pm
by Nigel Nobody
It seems that the laws of physics work differently in your area. Down here when you dilute something with water it makes it thinner, not thicker! I would not dilute it at all as that may also reduce the strength of the bond.

I wouldn't recommend gluing to foamboard with PVA or any other wet glue as it will warp and bend something fierce when its drying.

Additional material can be added to the edges of a canvas so that it can be stretched. Beva film and polyester fabric is ideal.I learned this method in Vegas at the WCAF convention in 2008 and it certainly has come in handy a few times.

Re: Diluting PVA 75/25 for Canvas to Foamboard

Posted: Wed 20 Jan, 2010 11:31 pm
by Not your average framer
Another option if you are one of those who stocks the materials, is to bond it to a larger canvas with lining compound.

Re: Diluting PVA 75/25 for Canvas to Foamboard

Posted: Thu 21 Jan, 2010 9:40 am
by Bagel Framer
Thanks guys - useful comments/tips as usual...!

The Gainsborough method sounds like the way to go - in the absence of PVA, presumably there is no other acceptable adhesive that can be applied and is heat resistant?