MITRA Forum Question Details

We generally refrain from endorsing brands here. When selecting linen artist's canvas, look for threads which are lustrous and smooth, without "slubs" (knotty inclusions) or bits of tow (straw residue). Flax that is cultivated primarily for high-quality fabric is planted with close spacing to induce the formation of a long, strong stem (bast fibers such as flax are taken from the stem). Flax that is grown for seed or mixed seed and fiber is spaced farther apart to encourage branching, so the resulting fibers are shorter and less consistent. Fabric made from long, strong "line" fibers will be uniform in appearance with very few slubs. The lowest quality "sacking" fabric has a loose single weave (single warp yarns and weft threads) and a lot of odd bits in it, too many to pick out. This type has been sold as a painting support in the past, but it had to be liberally slathered with sizing and priming to close the weave.

Traditionally, canvas texture was selected for the optical effect desired, and distance intended from the viewer, so a fine "portrait weave" would be chosen for works viewed at intimate distance, and where smooth, continuous brushstrokes and suave gradients were desired. Rougher weaves might be chosen for larger canvases viewed from a distance, where broken brushstrokes with a "dragged" appearance were intended, especially where colors would mix visually in the viewer's eye. Rough fabric does allow the primer to "key" on the surface well, but a good product applied correctly will work just fine on smooth fabric, especially if lightly groomed with a pumice stone or fine sandpaper before sizing/priming.

A good type of medium or rough canvas should still be woven tightly enough to avoid significant strike-through of the sizing and priming. Usually combination weave (single ply warp yarns and multi-ply weft) or double-weave (multi-ply warp and weft) are what you will want to select. The latter is better overall, especially for large scale works and for heavy paint; the former is a good compromise when budget is a factor. 

I think the OP might want to review the Golden posts cited- GAC-400 is the product recommended as a fabric stiffener and RSG replacer. 

A squeegee (the sort sold for printmaking) is a great tool for broadly applying thinned acrylic dispersion painting ground- much better than a die-punched plastic card. There is also the priming knife, indispensible for driving stiff primer into the weave of canvas with minimal force.

​Such a great response Matthew, thanks.

Hi - While Matt's response was good I also wanted to touch on some gaps regarding Golden's recommendations for priming canvasses, especially for oils, which is where and why GAC 200 got mentioned. If you read the following article, you will see that GAC 200 did perform best BUT needed to be applied and dry at 70F or above - and so is a solution that is not often pursued.

https://justpaint.org/preparing-a-canvas-for-oil-painting/

We also mention in that article how GAC 400 added a cumbersome step without really getting you better stiffness than just using three coats of acrylic Gesso. So, for simplicity, I would actually advocate going just a touch further and applying four layers of a good acrylic gesso and skipping the GAC 400 or GAC 200 altogether, as testing done by Marion Mecklenburg from the Smithsonian showed that four layers had just slightly less stiffness as aged lead oil paint. You can see that in the following article 

https://justpaint.org/using-oils-with-acrylics/

under the section titled: Acrylic Grounds: Impact of Thickness, Composite Structure, and Flexibility

As for GAC 200 and its usual limitation to use on inflexible supports, that is true - however, when used as a size and soaking into a canvas, especially when cured at 70F, it proved to have sufficient flexibility and passed all our tests. The canvas fibers here are changing and contributing to its mechanical properties vs when used as a solid and continuous film on its own.

Hope that helps.