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View Full Version : Pumice and Gesso, what ratio?


Ruthie57
12-08-2013, 08:58 AM
I have bought some clear gesso and some pumice powder in a sale. I have some mountboard (mat) which I want to prime with this to try out a new textured surface.
Does anyone know offhand how much pumice to how much gesso I should use? I'm assuming a little pumice powder will go a long way?
Also, when priming mountboard would you sand it first or is this not needed?
Thanks in advance :)

Donna T
12-08-2013, 09:41 AM
Hi Ruthie - Here is Richard McKinley's "Simple Grit Mixture No. 1" from his book Pastel Pointers:

1 cup (250 ml) acrylic gesso
1/4 cup (50 ml) fine pumice powder or marble dust
1/4 cup (50 ml) water

Mark Leach provided this information in Raw Colour with Pastels:

"Mostly I work on acid-free, extra-thick mount card, which I have primed with a mixture of one-third acrylic gesso, one-third pumice powder, and one-third water."

I didn't see that either recommended sanding the mount board first. I would worry that roughing up the surface might allow too much moisture to penetrate and cause warping but let us know what happens if you try it!

SSB
12-08-2013, 12:45 PM
The gesso can not adhere well if the surface is too smooth. It will appear to be doing so, but it won't last, it will move around and not go on well. I think you can get as much as equal parts pumice/ gesso, but a thinner solution double or triple coated seems to do better at dispersing the pumice. One thing, mix it really really well, and make sure the gesso is not thick at all, mine doesn't need thinning (Blick brand, not the "master" one though, that is the thick one)
and I apply it with a foam brush dipped in water and shaken almost dry.

Dougwas
12-08-2013, 12:57 PM
Hi Ruth. I don't know if you know this or not, but clear gesso (Liquitex anyway) already has some pumice (or something like it) in it. I use clear gesso on hp watercolor paper over an under painting for oil pastels. I think McKinley's recipe is for regular gesso.

Doug

Ruthie57
12-08-2013, 02:20 PM
Thanks Guys! I have primed one piece of board, plain gesso on the back and two coats of gesso with pumice on the front. I aim to work on it maybe Tuesday, to make sure it's dry. I've tried to leave brush marks in varying directions.....we will see!
Doug, yes the clear gesso does have a "grit". I have used it before and got a fairly good result. But it would not take many layers. Maybe it will be the same with the pumice added. It may help me loosen up, while carefully considering what I do, in case I cannot get many layers.

MChesleyJohnson
12-24-2013, 10:29 AM
When I make my pumiced gesso mix, I stir in enough pumice until, when I rub a little gesso between my fingertips, I can feel the grit. Also, I apply the gesso to the board thinly, and use several coats. The "tooth" gets denser and more consistent with the more coats I apply.

Dcam
12-24-2013, 10:36 AM
Hi Ruthie: I like Donna's ratio and you can color that gesso by adding thinned acrylic....especially fluid acrylics. The liquitex clear gesso needs two coats. I also like Golden fine pumice gel. I mix some with water and brush on the gesso surface. You don't have to wait all night like you do with the liquitex to dry.
Have fun Ruthie Q.
Derek:wave:

Ruthie57
01-09-2014, 04:17 PM
Michael and Donald :wink2: sorry I didn't reply. Was away for Christmas and then missed this on my return. Thanks for your suggestions. In the end I used the Richard McKinley recipe.....but I forgot to put in the water! Oh well, I gave it two coats and it seemed a good surface to work on. I'm planning another now, where the strokes of the brushed on gesso mix will, hopefully, go in the right directions for the painting I'm planning. Experimenting is fun!

woodenpalette
01-13-2014, 12:54 PM
Hi Ruthie: I like Donna's ratio and you can color that gesso by adding thinned acrylic....especially fluid acrylics. The liquitex clear gesso needs two coats. I also like Golden fine pumice gel. I mix some with water and brush on the gesso surface. You don't have to wait all night like you do with the liquitex to dry.
Have fun Ruthie Q.
Derek:wave:

Hi Derek - I also have the pumice gel by Golden and dont know exactly how to use this. I tried it once over a gesso board but the surface was so uneven I did not like working on it. I will try painting it on watercolor paper and see how it looks. How do you evenly apply this to the surface...do you use water with it?

Thanks!
Henk