[alt-photo] Re: PVA for SIZE & GUM ?‏

[geoff chaplin]

I'm confused and I suspect others are too. PVA is a non-unique name: looking at Wikipedia we have the following

PVA=PVOH=PVAL polyvinyl alcohol - the common brownish 'PVA glue'. (Something I have used to make 'gum' prints with and also as a size and it works well for both though maybe wouldn't suit the colour gum printers since it is difficult to get a really smooth and even single coat.)

PVA=PVAc polyvinyl acetate - white wood glue, sealant, used in bookbinding and is a raw material used to make PVAL. (PVAc is something I have used to make photosinks and tables with :-) but not gum prints.)

Now what is PVA size? One mail refers to it as PVAc while another says it is different from wood glue. I suspect the above two definitions of PVA are just the tip of the iceberg and there may be many polymer variants lurking under the PVA banner. It would be useful for us and future generations if we can actually pin down the chemical compound we do find useful as a size, rather than a product name for a product that may be gone tomorrow.

Incidentally I and others have had good results from Windor & Newton's Acrylic Clear Gesso Base (contains 'acrylic co-polymer') and also Kusakabe Gesso as a size.

Geoff Chaplin
 ジェフ　チャップリン
 
geoff at geoffgallery.net 
www.geoffgallery.net  
Skype: geoffchaplin1611
UK mobile (英国の携帯電話): +44(0) 7770 787069
Japan mobile (日本の携帯電話): +81(0) 90 6440 7037
Japan land line / fax (日本の電話とファクス): +81(0) 166 92 5855