Dear forum members,
I’m on the verge of adopting the practice of sanding sized canvases. I can thus remove unwanted knots and irregularities in the surface. First, I put two thin coats of PVA size on the stretched fabric, sand it smooth with fine sandpaper, and lastly, I apply another two thin layers of size. This way the PVA mitigates the damage/fraying, and I have a nice smooth surface to work on. By the way, I expected a Claessens 13 fine weave canvas to have virtually no knots, but I guess it’s just the way fabrics are.
The simple question is: are there any concerns with this practice that I may not foresee? Should knots be “flattened” this way? An alternative would be sanding the canvas in between lead oil ground layers, but honestly I’m not keen on trying that one.
Kind regards,
Peter
Hello Peter,
Nothing sounds ominous in what you’re saying. It’s obviously safer for your health avoiding sanding lead carbonate dusts. It’s also very good you operate in thin layers with time to dry independantly.
Just a wonder, depending on the size of works you do, why not considering wooden pannels? They’re easier to get smooth, if you don’t mind losing the bounce of the cloth.
There’s also options of metallic pannels, with obvious drawbacks.
If the canvases are already primed with acrylic I’d prefer using acrylic gessos, but the difference between PVA and Acrylates is rather thin to my understanding.
People with more restauration experience might comment on delamination risks if any.
Cheers,
Lussh
Thank you for your input!
Do not sand lead white paint. I also greatly prefer to control the smoothness of a oil ground by application (a priming knife) and the number of coats.
I always apply size after any sanding and do not sand the final layer. Your thoughts are good. Linen will always have some imperfections or at least has a non-homogenous surface. In many ways, that is why I greatly prefer it to the mechanical nature of cotton duck. For slubs, I like to place the canvas or a stack of books etc so that any pressure from the front will not distort the planarity of the canvas and only sand the slub itself. This allows you to flatten the slub but not overly sand the surrounding area.
You can certainly apply an oil ground over these polymer sizes if you want. I prefer acrylic to PVA.
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