Saturday, May 21, 2011

priming and sizing


If acid in paint cause canvas to deteriorate HOW would oil primer (which is an oil paint) prevent it? ? Is a quality oil paint PRIMER from paint store great to use??
This question came up in a forum on the Internet, I guess I was cc,ed because my name was mentioned so I will answer it.

The acid in oil paint will cause damage over time to your canvas. That is why you cannot prime raw canvas with oil primer. It is necessary to first apply a size layer. There are commercially available products that are ready to go, but your canvas MUST be isolated by a sizing layer before the oil primer goes on. Rabbit skin glue and or gesso (real gesso not acrylic polymer) is the other fix. Of these I think the commercial sizing is the easiest and simplest. Also rabbit skin glue is hydrophilic, that is it absorbs water and that makes your canvas come and go more with the barometer.

For me the real question is why bother with priming your own canvas? There are so many kinds of preprimed canvas available and there is even an inexpensive oil primed linen available from Jerrys called Centurion. It is made by the Chi-Coms but it seems to be OK at least for its price.Frerix makes a nice heavy oil primed cotton, called Scarlett O'Hara, too. That is also inexpensive.

A coat of oil paint over an acrylic canvas might be a good solution too. Stretch the canvas and put the oil paint over it, then set it aside to dry.Cheap, and oil primed. Paint does sit better on an oil ground and it feels silky under the brush.

Oil primer made for house painting is OK on rigid panels, I use it a lot. But it should not be used on a canvas. I don't think that is good at all and I think it might crack.

I don't really see what is to be gained by priming your own canvas, my time is precious and I want to use as much of it as possible painting. Inexpensive acrylic primed cotton can be had very cheaply and is just fine, unless you are a pro. I feel the same way about grinding paint. There are materials freaks out there who really enjoy custom making there own materials and that's fine for them, but I just want to spend my time painting and let some one else prepare my materials. It ain't in the paint.

22 comments:

willek said...

Yes, some of the Sherwin William primers dissolve in Terpinoid and Gamsol. Pretty disturbing when doing wipe away beginnings. So I am back to using acryllic gesso on my panels again. You could do the commercial primers and then put down a layer of gesso. That keeps it all in place.

Stapleton Kearns said...

Willek;
The Zinsser oil primer seems not to do that. SW reformulated their oil primers and they are now useless for our purposes.
...............Stape

Deb said...

I've found that adding a thin layer of flake white (the real lead stuff)
over even cheap cotton canvases makes a great painting surface. I also like the Centurion, and sometimes for extra smooth non absorbent surface will apply another coat of lead to those too.

Brady said...

I love the license plate! Is that new?

But I do wish someone would come out with a good oil primed panel that didn't cost a lot.

David Teter said...

I paint on rigid panels most of the time which I prefer since I don't care for the springy, textured surface of stretched canvas.

I am in agreement on the time factor of preparing surfaces/materials to paint on, I would rather spend that time painting.

That having been said I do prepare my own 'masonite' panels since the ready made (archival) ones at art stores seemed rather pricey and are only available in certain sizes.
I did do some research on that topic so I could avoid any potential problems with acids in the board and primer resulting in archival issues.

Here's what I found out: It is ok to use 'masonite' from a lumber yard IF you don't use tempered board since there is oil used in the MANUFACTURING PROCESS.
I have seen info suggesting that oil is added to the pulp mix then pressed into boards to make it tempered. My understanding is that is not quite true.

The oil is used to lubricate the heated press plates so that the mixture doesn't stick to the plates, so that they release. This is why they are called tempered, they are heat tempered not oil tempered. The result is some absorption of oil into the finished panel, still not good though for potential acidity and maybe long term archival adhesion.
Not trying to split hairs here but I won't use them for that reason.
Generally tempered boards are smooth on both sides.

'Masonite' that is safe to use is usually smooth on one side and 'waffle' textured on the other.
This process is safe because no chemicals or oil are used in manufacturing or the pulp mix, only water.

Much like paper making the pulp mix is pressed but not heated and (through some kind of science principle that I can't remember) it sticks together.

The article in an art trade magazine I read did say always check with the manufacturer to be sure no oils or chemicals were used.

The house oil primer/archival/acidity issue was another. Info was tougher to find.

Since some house oil primers MAY or MAY NOT contain ingredients that could be a problem I try to avoid them (that sounds a bit like russian roulette) and use Zinsser's B-I-N primer. It is shellac based, will lock out or seal the surface, stick to anything, and can be top coated with anything, which I coat with gesso (after a light sanding) for a toothy but still smooth surface.

Shellac is apparently made from the gum from some tree and is supposed to be safe archivally speaking.

But hey, I'm no expert, this is what I found through research. Just because it is written some where does not necessarily mean it's true. If anyone has heard otherwise speak up.

I still don't like the time away from painting to prepare these but at least I can make any size I want and not spend a fortune just for the surface.

If I buy a couple 4 x 8 sheets at about $20-$40 bucks depending on thickness, and cut and prime, I'll spend a day and have a couple months worth of painting surfaces, so not too bad.
When I can afford an assistant... I won't even loose that day...

Bill said...

Some artists like to prime their own linen canvas because the sizing step shrinks it to make it tighter than they could stretch it by hand if they used pre-primed canvas.

I like to prime my own panels because I like to experiment with different textured or colored surfaces, such as rabbit skin glue/marble dust gesso or various acrylic dispersion mediums. The ground has a profound effect on the appearance of the finished product depending on its texture, color, and absorbency.

I do also use plenty of pre-primed canvases and second the endorsement of Centurial OPL, but I would encourage artists to at least learn the process of priming their surfaces. Even if you are going to skip that for most of your career, you should be aware of what's involved.

billspaintingmn said...

Stape! I'm in a process of Freeing up myself, so I can better do the trip. Paint and live is how I say it. Time is all I have.

Birch or basswood boards with a traditional gesso as primer is what I like to paint on. Rabbit skin glue(drk. german) is my prefrence.
Marble dust is nice, however there are other grounds to use, bone, alabaster,even some limestone works well.
I would not use this on canvas, as it will crack. I'll give the zinsser oil primer a try on canvas.

Sizing canvas with "RSG" and then priming is still a crap shoot, you really have to saturate the canvas, and then there still is no guarantee.
My art freak-ness is driven by my curiosity.
For now I just want time to paint!

Moose said...

Bill, I'd like to hear what your mixture is for Marble dust gesso. I've just started messing around with the stuff- LOVE the texture, but am often frustrated with the super absorbency of my mix. Would be great if I could find out what others are doing, if you're willing to help out. :)

Stapeliad said...

Cool license plate!

Brady said...
This comment has been removed by the author.
Emmett Ryan said...

Stape are you doubleparking in NH

Stapleton Kearns said...

Deb;
That works well. Are you mobile now?
.........Stape

Stapleton Kearns said...

Brady;
No I have had that plate for many years.
..............Stape

Stapleton Kearns said...

David, See tonight's blog.
........Stape

Stapleton Kearns said...

Bill that shrinking thing is a nice feature, but I don't have time to fool around with priming my own canvas and the commercial is better generally.
.Stape

Stapleton Kearns said...

billspaintingmn;
Perhaps others will post their methods in the comments.
...............Stape

Stapleton Kearns said...

Moose;
I don't like very absorbent canvas.Or sports.
................Stape

Stapleton Kearns said...

Stapeliad
Thanks;
.................Stape

Stapleton Kearns said...

Emmett;
What?
..................Stape

Bill said...

Moose: I'm probably not the best person to ask for gesso formulas. I basically follow the guidelines I've seen in artist's manuals like Mayer. Danny Van Ryswk has published a fairly complex procedure on his web page (http://www.dannyvanryswyk.com/ - scroll down and you'll find it), but I confess I have not bothered with all that. If you want a perfect smooth surface, you probably do need to follow something like that, but my formula is often as simple as RSG mixed with marble dust to a milk-like consistency. I have had some luck avoiding pinholes by first mixing the marble dust with water alone to a putty-like consistency, working the two together on a glass slab with a palette knife and then carefully mixing this with the RSG. Once you've got this mixed up, the procedure is to lay out a bunch of panels and start laying it on, adding new coats as soon as the previous coat is dry to the touch. You probably need at least 4-5 coats, but 8-10 are probably better. After it's dry, you can sand it.

It does need to be sealed in some way to cut its absorbency. Shellac or varnish are often recommended, Lately, I have used Golden GAC 100, which is pretty unconventional, but seems to work well, and everything I've read tells me it should be stable. Sometimes I mix pigment or acrylic paint with the GAC 100 to color the surface.

Also, you should seal both sides of the panel first with RSG. It's a good idea to apply a few coats of gesso to the back as well, to prevent warping (also makes a nice surface to write information on the back). Anything larger than 8 x 10 inches probably should be cradled, but for anything very much larger than that I usually go for canvas.

Sometimes I wonder why I spend time on this sort of thing when I could be painting, but working from the ground up holds a certain fascination for me. The results are often intriguing.

George Perdue said...

You are right Stape, Zinseer does crack on canvas. Big time ugly. Scraping off is tedious. Sealing with alkyd butter might be OK, time will tell.

Urban Wild said...

I'm a new reader of your blog--and I've learned a TON of useful things here so far.
I came into possession of about 40 5-ply plywood panels, slightly larger than 9 x 12, all perfectly cut, which I want to use to paint on. I prefer a rather smooth surface; I've recently using Panelli Tetlani panels and really like the surface of these--it was a revalation after using cheap cotton canvas panels with their fairly rough tooth.
I don't have a ton of money, but what would be a good smooth pre-primed linen to mount on these panels?