Paint and gesso question

[Eltz-Kempenich]

I recently completed my new shield, an aluminum heater covered with canvas. I gesso'ed the surface and encountered something odd. I found that the acrylic paint went on very thin and splotchy, and required about a million coats to achieve an even finish. When I did my first shield, I used the same paint directly on the canvas and it went on very nice and thick and yielded a very solid, even finish. Is there something I am doing wrong, or another paint I should use over gesso? Is this inherent with surfaces covered in gesso? Or should I perhaps use more coats of gesso? Any insight into this would be helpful for future reference. Thanks!

[Frederich Von Teufel]

Hmmmm. The gesso should have provided a very nice primer surface for the paint to adhere to.

Quick ideas:

- Could the gesso surface become contaminated in the time it took you to get around to painting it?

- Did you sand the surface of the gesso before painting; not an absolutely necessary step, but one that I like to do when I remember.

- Was the paint you were using an old paint? Did it get thoroughly stirred/shaken before using? Check the label on the acrylic paint and make sure that there isn't a incompatibility issue with it being used over gesso (I can't think of anything off hand that shouldn't stick easily to gesso, so I think this is a long shot.)

- Paint is made up of three main components, the pigment, the solvent, and the binder/vehicle. The blotchy and thinness of the paint really says to me that there is an issue with the paint itself, probably that it is either too old or didn't get mixed well enough.


Frederich

[Ernst]

Was the paint left in a location where it could have frozen and thawed?

[InsaneIrish]

How many coats of gesso did you use?

What did you use for Gesso?

the glue/binding may have soaked through the canvas and gesso to interfere with the binding of the acrylic. Maybe

What you used for gesso may not have been compatible wit Acrylic paint.

The acrylic may be old/bad.

[Eltz-Kempenich]

The paint may have been old, as I bought it last spring, but I don't think that is the issue. I bought new paint, same brand as the gesso, made for applying over the same gesso, and had the same issues. I only used one coat of gesso, as that seemed sufficient for the finish I wanted. I did not want to sand it, just impregnate the canvas sufficiently to help prevent against the canvas from tearing. Perhaps it needs a longer curing time than I allowed, even though the bottle said it dries in ~15 min.