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Barbara WC
09-23-2008, 11:59 AM
I have a canvas that I seriously messed up- I was trying to make a toned background, and ended up with a gray mess which wasn't what I was going for.

I know I can repaint over this. But, I'd like to start with a white canvas again.

How to do this? Do I cover with white acrylic paint? Or Gesso? (I've never used gesso).

thanks.
Barbara

Aires
09-23-2008, 12:27 PM
:thumbsup: Certainly you can paint over the canvas - my own preference would be with gesso as it is cheaper than tube paint and it gives the same surface you began with. Other times it is just as well to simply begin again right right over the dried paint that muddied. Perhaps this will help - next time try misting your canvas very lighty before starting your toned ground...if it isn't what you want you can wipe it off as long as the canvas stays damp. The dampened canvas keeps the paint from grabbing the canvas and also lets the paint move around freely for blending. -- Is it really necessary to return to a white background?

George Servais
09-23-2008, 12:32 PM
Use a quality Gesso like Grumbacher Acrylic gesso. Just make sure that the gesso is pigmented well.Cheap gessos are almost a white wash and aren't worth the time and trouble. Just paint it on with a large bristle gesso brush. They are cheap and available at any art supply store for under $4.00. Use more than 1 coat if necessary. Sanding between coats is optional depending on how smooth you want the surface to be. I read here a lot about sanding between coats but it really is unnecessary unless you want to have a super smooth surface or if you leave a lot of brush strokes during the application. Just be aware that the more coats you need to apply the less tooth your canvas will have. You can actually tint the gesso with color and apply it to tone your canvas if you wish.
As far as using white paint there a few reasons why you should not chief among these is the expense, gesso is cheaper (much cheaper) than paint, secondly acrylics do tend to be quite transparent and to achieve full coverage you will need quite a bit of it. That is expensive.

Barbara WC
09-23-2008, 12:43 PM
I probably don't need a white background, but I'm a newbie and find the dark background distracting. I also want to completely change the subject matter.

Great info about misting and Gesso.

Thanks-
Barbara

ColorMyWorld
09-23-2008, 02:29 PM
Also to help the paint spread around, coat the canvas with Golden's GAC100 medium. This helps the paint go on much smoother.

Mixael
09-23-2008, 02:35 PM
Barbara, if you're going to completely change the subject, then jsut gesso over it. I know the others have mentioned it, but I have to agree with them. Using paint, though it would work (even if it takes a few coats), would cost MUCH more than using the same amount of gesso. And depending on how dark the canvas is now, coupled with how thick you put the gesso on (I'd recommend several thin coats, allowing them to dry comlpetely between coats), you may have some "bleed through" of the dark stuff. Don't worry, additional coats will hide it.

As far as coloring the gesso, you could add a drop or two (or three or four) of the color of your choice (black, blue, sienna, even puple) to tint the gesso without making it dark.

My current trend is to leave it stark white, but that's because I don't want to tint my entire thing of gesso, and haven't gotten around to mixing a small amount of gesso and paint in another container. And that is in spite of the fact that I find the whiteness of the canvas a bit intimidating:D

Well, I think I've written enough for now, and proably gotten you confused, I'm going to stop.

Michael

Blick Art Materials
09-23-2008, 03:45 PM
Hi Barbara,
It's debatable whether to gesso over existing paint, because gesso is formulated to be a barrier layer between the substrate and the paint. Some would advise against this application, because of the concern that it would be an improper adhesion long term. If you want to play it safe, we would recommend working with a block out white acrylic paint. It is a heavily pigmented, opaque white paint that will coat over your existing colors, yet it's formulated to be compatible with other acrylic paints. It'll have the workability and the flexibility you find in acrylics.

Kristal

Jesse Riggle
09-23-2008, 03:49 PM
I've messed up a good many canvases and I have found a quick layer or two of Gesso works well. If there is concern over adhesion, then white paint. Or you could try sanding the thing down. or just paint off the gray background. I find it is nicer to paint of something that isn't white anyway. I find white surfaces (for acrylic anyway) tend to lead to flatter feeling paints. But that is just me...

halthepainter
09-23-2008, 04:11 PM
I personally give a light sanding then gesso.

For future reference see if you can find a Jerry Yarnell demo on how he tones his canvases. If memory serves, he uses a thin gesso, I think it's Goldens, with a pour spout, and covers the canvas with it then paints his hue into the wet gesso and blends the whole surface at one go.

In fact I think he also wets the canvas before the initial gesso application.

Aires
09-23-2008, 08:18 PM
Halthpainter, you are so right. I have the Jerry Yarnell video where he does just as you described, painting his back ground colors right into that wet gesso so that it blends beautifully. And he always uses a mist on the canvas before starting a painting. Saves a lot of expensive paint but it allows the paint to move around smoothly. Note that you must learn that misting the Yarnell way requires just a bare sheen of water on the canvas, something you learn by doing. If it runs, just blot and proceed.

It's only my two cents worth but I've had no adhesion problems when painting over an old painting with Golden Gesso. It is a heavily pigmented gesso and I find it adheres very well, in fact just try to get it off without a lot of hard sanding! I'm not on the Golden payroll but know a good product when I find it. You can find cheaper gesso but it takes more coats if it does not have a heavy pigment load. To my mind, a good gesso and a fine mist sprayer are necessities to painting easily with acrylics and in keeping them from drying up. Not everyone will agree with me but I like to roll on my gesso with a small paint roller rather than brushing it. One WC member recommends popping the paint roller in a plastic bag and storing it in the freezer until needed again - I have not tried that yet, I just wash mine well but the hint was that it saves a lot of gesso to leave the gesso in the roller and just freeze it for future use. Can't vouch for it yet but will try it next time I use gesso.

Mixael
09-23-2008, 08:48 PM
I've also been told (by painter (not artist kind, the other) that I know) that you can take a large plastic bag with a small amount of water in it, put the roller in, and TIGHTLY seal the bag around the roller handle to seal it. May not last as long, but several days at least.

I've never tried that, so don't know if that really does work.

Michael

Aires
09-24-2008, 07:59 PM
I was afraid I'd get a lot of flak for mentioning using a roller for gesso. But I want to get that gesso on and done with so I can get back to the real fun, painting that picture my fingers are itching to try. I find that with the heavy load gesso, it is harder to get an even coat spread over the substrate without leaving brush marks. Any texture left by a roller is slight and easily rubbed down with either one of those little green kitchen scrapers or with sandpaper, just takes minutes and your ready to go. There is a very heavy gesso made just for hardboard or any nongiving surface like metal. It needs no primer and one coat is said to be sufficient. I have not yet tried mine but feel the roller will certainly be helpful with even thicker non-flexible gesso. Anyone else tried that hard surface gesso that cannot be used on canvas?

AMuse
09-24-2008, 08:10 PM
I have read that freezing destabilizes acrylic. So, personally, I wouldn't store it in the freezer - just wrap really well and try to gesso a lot of surfaces in one sitting so you won't waste much. :)

Aires
09-26-2008, 06:17 PM
Kathy, you may be right. I wonder if the very small amount of gesso left in a roller would make much diffference when it thaws out for re-use. After all, you immediately put fresh gesso on your substrate to proceed with the next job?? Just a question that comes to mind because I would not leave any more gesso in the roller cover than possible no matter how I store it.

RichDFischer
09-26-2008, 07:38 PM
Yah - don't freeze the roller. The gesso will stay moist for about a week in a plastic bag, any longer than that it will start to mildew. Freezing will seperate the latex in the paint.