absolutely, more coats of gesso will make the surface more absorbent, not less, but a bit of preconditioning medium will make it less absorbent. in fact, it is a best practice to do that instead of starting a painting on bone dry gesso.

I buy acrylic-primed canvases routinely, and I flat-out always add at least 3 additional coats of acrylic gesso. I use Grumbacher’s 525 Acrylic Gesso, and I thin it with water until it is spreadable with a brush.

I feel that manufacturers do not apply enough protection for the canvas. Acrylic-primed linen is notorious for not having enough acrylic priming. Pinholes are quite numerous in acrylic-primed linen, pre-stretched canvases, and to me, each pinhole represents a weakness in the coating, where oil paint can seep into the fabric, subjecting it to deterioration.

In short, I consider 3 extra applications of acrylic primer (thin enough to be brushable, and self-leveling) to be minimum for each acrylic-primed canvas that I purchase.

I buy cheap canvas boards for small studies, experiments… and I don’t add gesso. But if I am going to spend 40 or 80 hours on a painting, I don’t mind spending an extra 30 minutes giving two more layers of gesso. I consider it an investment, taking care of the painting.

I know many add one or more layers of gesso to pre-gessoed commercial canvases – some because they don’t feel there is enough on it/too absorbent, some because they want a more smooth surface.

Is it necessary? If I feel the surface is smooth enough? [/quote]

Nope. If you like the surface as-is, then just use it as-is.

[QUOTE]Also, if I wanted to add a coat of something to make it smoother or less absorbent, could it just as well be a toned coat of thinned oil paint instead of gesso?

A thin (presumably wiped) coat of oil paint like you might use for toning is not going to reduce absorbency by any noticeable amount. If you want a less absorbent surface, a single coat of oil (not acrylic) primer will do the trick.

I know many add one or more layers of gesso to pre-gessoed commercial canvases – some because they don’t feel there is enough on it/too absorbent, some because they want a more smooth surface.

Is it necessary? If I feel the surface is smooth enough?

Also, if I wanted to add a coat of something to make it smoother or less absorbent, could it just as well be a toned coat of thinned oil paint instead of gesso?

My problem is that the smell of acrylic paints – alkyds? – and gesso make me queasy and give me a headache.

I’m with Bill on this one.
You don’t know the number of coats acrylic gesso that the manufacturer applied, and tests by Golden show that at least 3 coats are needed to stop strikethrough, (oil penetrating through to the canvas).
Also, you don’t know what they used, and different brands of acrylic gesso have different levels of absorptiveness, which will also effect strikethough.
So adding additional layers of acrylic gesso is safety measure to make sure you don’t get any oil in the canvas which will eventually rot it.

No, no…..Oil paint is what we’re trying to protect the canvas material [I]from[/I]. A coat of oil paint most surely will not protect the canvas from ….oil paint.

:thumbsup: :thumbsup:
Well said, Bill!

Have you considered buying oil-primed canvases? They are somewhat more expensive, but would eliminate the need to work with acrylic gesso.