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cobalt fingers
09-17-2002, 09:57 AM
I was just looking for the talk about PVA size as used on raw linen-my search found nothing. where dat be? And any more news? Can we paint on it? will it bleed? will the oil bleed out from the color areas and leave little oily halos?

scottb
09-17-2002, 10:01 AM
Here is what I came up with via a search here:

http://www.wetcanvas.com/forums/search.php?s=&action=showresults&searchid=78508&sortby=lastpost&sortorder=descending

Cheers.
Scott

cobalt fingers
09-17-2002, 11:33 AM
somewhere some of the 5really informed fellers were fussing about primimg and sizing with PVA. I remember it was a good talk. I just didn't find it in the above discussions just listed. maybe it was a little side discussion that was borne from another topic-any hints or remarks about this subject?

I really like the look of raw linen amnd would like to think I can use the PVA and go if I start out lean. Is not the only trouble-starting out tooo fat and getting fatter?
And if I working alla prima would I not be fine?

scottb
09-17-2002, 11:41 AM
Originally posted by cobalt fingers
somewhere some of the 5really informed fellers were fussing about primimg and sizing with PVA. I remember it was a good talk. I just didn't find it in the above discussions just listed. maybe it was a little side discussion that was borne from another topic-any hints or remarks about this subject?


I originally searched for "PVA* size". Here is a broader search, of just "PVA*":

http://www.wetcanvas.com/forums/search.php?s=&action=showresults&searchid=78551&sortby=lastpost&sortorder=descending

I really like the look of raw linen amnd would like to think I can use the PVA and go if I start out lean. Is not the only trouble-starting out tooo fat and getting fatter?
And if I working alla prima would I not be fine?

My instinct tells me that you are correct, but I must admit, I'm not overly familiar with the effects of sizing materials on surfaces.

Cheers.
Scott

puzzlinon
09-17-2002, 01:30 PM
Yes, PVA will seal the canvas and protect it from the oil. Just don't be stingy when you put it on; work fast (it gets tacky quickly) and use lots so you don't leave holidays. If you're paranoid, you could experiment with using an isolation varnish on top of the PVA, but that's probably overkill.

If it's the look of the linen you're after, more than the texture, you could put a couple of coats of PVA down, sanding after the first one (PVA is very sandable.) That would also free you up to paint however you wanted from the start.

Linoxyn
09-17-2002, 01:35 PM
Tim, you can paint in oils (fat or lean) directly onto linen that has been properly sized with either RSG or an artist quality PVA. If you are going to do serious work on such a surface it may be wise to create some test swatches of examples of how you would paint on this, run them through some tests and observe them over time.

It's great to get feedback from other artists when it comes to trying something new, the welcomed advice can help us get to our answers quicker - in the end it comes down to the many variables we uniquely bring to our own materials and methods that will lead us in the right direction or not.

best of luck :D

cobalt fingers
09-17-2002, 10:40 PM
Thank you all,

One of my students just had preped linen work-she just reversed a failed painting and began the work for the class. I got to paint on the surface as part of a demo and loved the tooth and the casual look. I bought some Gamlin PVA size that day.

I feel good about the new ideas-thanks to you.

Tim

donjusko
09-18-2002, 03:23 AM
I prime my oil palette with a non porous vinyl like PVA. I do this so I can peel off the dried oil paint. A ground should be porous.

JeffG
09-18-2002, 09:09 AM
I'd suggest doing the first coat of sizing with a diluted mix of PVA, say 50/50 PVA/Water. Then follow with at least 2 coats of full-strength PVA (first brushed 1 way, then the other) to ensure full coverage. If no wet spots appear on the back of the canvas on that second coat, its probably covered enough.

My experience with PVA is for sizing paper to paint on. However, this is the way I used to prepare canvas for acrylic painting to keep the acrylic gesso from coming thru the canvas.

Linoxyn
09-18-2002, 09:33 AM
Originally posted by donjusko
I prime my oil palette with a non porous vinyl like PVA. I do this so I can peel off the dried oil paint. A ground should be porous.

Tim, as in this quote from donjusko and from what JeffG has stated - if you apply a coating that is meant to size a surface in a manner that seals it or diminishes the properties of a surface to the point oil paint does not adhere well to it... well you know what I'm saying here....

Drop an email off to Robet Gamblin they will tell you exactly what their testing shows and will offer you the best rate of application to provide the right amount of protection to the linen and at the same time provide the best painting surface for your oils.

cobalt fingers
09-18-2002, 01:48 PM
Good idea,

I was ready to jump in-buy want to be sure. Where's ole Luis anyway?

I have found acrylic gesso to be pretty slick but lots of people use it and clear acrylic as a size just before painting oils onto it. I'll see what Mr. Bob has to say about his product. Thanks guys all. Tim

donjusko
09-18-2002, 04:30 PM
Hi,
Let me say some more.
PVA could replace the rabbit skin glue, that would work.
But who would paint on the size?
Over the glue you need a white absorbent ground. Colored grounds are all right if you want but they shouldn't be left as final paint.

Here is a fairly unknown point. You can use acrylic gesso on your oil palette also. The oil paint will peel off. I've done it. What this says is that it is the texture of the cloth only that holds the oil paint. What that means is don't use non absorbent crylic gesso for oil paint.

cobalt fingers
09-18-2002, 07:07 PM
(Hi Don)

I don't know if it's fair to say acrylic gesso and PVA act the same. Some v"very learned people hav blessed this PVA-I'll keep you updated. I simply don't understand why an oil painting primer would stick to the size and NOT oil painting.

Is this overly simple?

decoration attached:

scottb
09-18-2002, 07:36 PM
Hi gang. Was speaking with Martha Gamblin today, and here is some info that might be helpful:

PVA (Jade) from Linco is very good quality for painters
who want to dilute full strength PVA to make their own size. Gamblin PVA is already diluted for use as a size. Scrub into canvas or linen with stiff bristle. Take about 24 hours to dry. If painting directly on PVA, apply diluted PVA to both sides. ONE COAT only both sides. PVA does not tighten the fabric like Rabbit Skin Glue so stretch as if applying acrylic ground. the definitive study on PVA in the oil painting process is from the Canadian Conservation Institute in Ottawa.

Cheers.
Scott

cobalt fingers
09-18-2002, 09:01 PM
I got the same word from uncle BOB---go forth and enjoy.

Rob from Cennini forum also blessed the use of it-just not too thick.

donjusko
09-19-2002, 05:20 AM
Hi,
I said the PVA size would act the same as rabbit skin glue, but also said a ground should be absorbent. PVA would stick to the canvas but a non porous layer is not a good layer to paint on. Acrylic gesso is a good stick to likw rabbit glue or PVA and would work for acrylics but oil doesn't stick well to acrylics as they are non porous. Glue based oil gesso would both stick to the PVA and be absorbent. Plus being a much better surface for most painting. Would the oil paint stick to the PVA? I didn't on my palette, why should it on your canvas. If you had a lot of texture on the canvas that would help. Until the paint shrunk and pulled loose of the non absorbent PVA.

cobalt fingers
09-19-2002, 12:39 PM
Don, everyone on the site including me for years has painted onto acrylic gessoed canvas without the paint falling off. I've never heard of anyone using any size at all before putting on acrylic gesso-it's nearly always put directly onto the weave (raw weave) for better mech. bonding.

Additionally Robert Gamlin, Scott B. and several others have said that using ONLY the PVA correctly is fine.

I still do not see what's so important about painting on some white oil paint (calling it a primer)--what makes that white oil primer adhere any better than my other oil paints?

I think the best we can do on sites like this is to agrue the details out back and forth for all our benefits. If I missed something -please set me right, I'll appreciate it.
Tim;)

donjusko
09-19-2002, 05:35 PM
Hi Tim. You said:

Don, everyone on the site including me for years has painted onto acrylic gessoed canvas without the paint falling off.

I say it's not a good idea to paint oil on acrylic gesso.
It doesn't stick to my palette, So it can't stick very well to a support.

You said: I've never heard of anyone using any size at all before putting on acrylic gesso-it's nearly always put directly onto the weave (raw weave) for better mech. bonding.

I said, I agree, acrylic gesso is an all in one size, isolator and ground, for acrylics only though.

You said: Additionally Robert Gamlin, Scott B. and several others have said that using ONLY the PVA correctly is fine.

I say PVA is OK to paint on with acrylics. But because PVA is insoulable and without texture, oil paint will only be holding on to the texture of the cloth. OK, that will work for a couple of years, but does not stick on my hard my palette. PVA is flexible and stays that way, just like acrylic paint, no problem. There is the problem for oil paint though, which is not flexible. Oil paint gets harder and would prefer to shrink.

I say, Oil will destroy natural fiber but not synthetic canvas which you could paint on directly with oil or acrylic paint.,
Oil paint needs first, a raw fiber cloth, than an isolation from that cloth. The isolation size medium has to be a water soluble glue to hold a middle layer that will hold both the canvas, size and oil paint together. That layer is called a painting ground. It has to have the same soluble glue in it as the size so the two are bonded as one layer. That ground also has to have chalk, light spar gypsum or marble dust and some zinc white body pigment in it to make an absorbent layer allowing the oil paint to bond. Alum will make it unsolublele if you are working in tempra. For oil it is perfect and waiting for the oil based gesso. Oil paint on the oil gesso completes the bond.

I say, Do what you like, but do this test first.
Apply some PVA to a board and let it dry. Squeeze out some fast drying oil color on it and wait a few days till it's dry. If you can pick off the blob with your fingers and it doesn't adhere very well. Well, you decide if you want to apply paint that way.

You said, I still do not see what's so important about painting on some white oil paint (calling it a primer)--what makes that white oil primer adhere any better than my other oil paints?

I say, Tim, white oil paint is not a primer/ground for oil paint. Oil needs isolation from the canvas, even from a board. It's better to use a water based commercial primer/ sealer on wood then an oil based primer.

You said. I think the best we can do on sites like this is to argue the details out back and forth for all our benefits. If I missed something -please set me right, I'll appreciate it.

Here is what I think is the best solution, low cost and effective.
You don't want to use an isolation primer on your cotton or linen canvas, Ok, and don't want to use an absorbent ground for oils, Ok.
Use a cloth that doesn't need anything for any type paint. A synthetic canvas, I think they are the best anyway. That's what I use.

puzzlinon
09-20-2002, 12:54 AM
I say, Do what you like, but do this test first. Apply some PVA to a board and let it dry. Squeeze out some fast drying oil color on it and wait a few days till it's dry. If you can pick off the blob with your fingers and it doesn't adhere very well. Well, you decide if you want to apply paint that way.


Have you tried the same test with an oil ground? Put some on a smooth board, let it dry completely, put a blob of oil color on it, and see if you can pick it off. I suspect you'll find it comes off suprisingly easy. Palette boards are much smoother at the fine scale than canvas, even sized and sanded canvas, ever would be.

PVA as primer for all kinds of overpainting (latex, alkyd, and enamels) is commonplace in commercial finishes. It's also got a lot of uses as an adhesive; it's decidedly not difficult stuff for material to bond with.

I've done a bunch of things, building up from PVA size, with and without acrylic gesso, with oil at the top. Never any adhesion problems, and some of the bigger things have been handled pretty casually for several years of banging around.


By the way, the discussion switches between talking about "Acrylic Gesso" and "PVA" as if they were the same. They're not; PVA is one of the ingredients in acrylic gesso, but there's also acrylic medium, etc. Plain PVA plays the same role as rabbit glue; it's a size and canvas sealant, not the ground surface. When Gamblin talks about painting directly on PVA, he means the plain PVA (he sells it as an archival replacement for rabbit glue. The reassurance he's giving isn't about bonding, it's about canvas safety - the PVA does protect the canvas, with or without a gesso coat above it. (I don't think it would occur to him to say that PVA is OK for oils to bond to, because that's just a commonplace - PVA is glue.)

donjusko
09-20-2002, 05:04 AM
You said, Have you tried the same test with an oil ground? Put some on a smooth board, let it dry completely, put a blob of oil color on it, and see if you can pick it off.I suspect you'll find it comes off surprisingly easy.
I say you are wrong, and it's been tested for 500 years, oil paint will bond to a pourious surface but not a non pourous one.

Oil Paint bonds to an oil ground. It just sticks the best it can on a nonpourious film.
Both PVA and acrylic gesso are non porous and oil paint won't stick to them long.
20 years is not long.
PVA is non soluble rabbit skin is. Rabbit skin glue bonds with a glue ground that allows oil to absorb and form a complete bond.
There is no bonding with oil on a slick non absorbent film of PVA or acrylic gesso.

cobalt fingers
09-24-2002, 03:59 PM
I'm doing an important painting under my normal pressures-no time for mess-ups here. I'll let you know if it works or blows up. (In truth, I won't waste the ffort were I in any real doubt.) Don, I don't think this PVA is truly a Vinyl...maybe the slight difference is an essential one.

Glad to hear from you gain by the way. How's paradise?

Tim

donjusko
09-24-2002, 04:58 PM
Poly Vinyl Acetate is a true vinyl :)
Maui is perfect weather, all the time. Thanks.
Don
Why don't you use the synthitic canvas I suggested?

cobalt fingers
09-24-2002, 05:21 PM
Don, I find the tooth too regular and sterile...kinda silly I know but the best thing original art can have is soul. I try to feel soulful. I like old wooden palettes even if their not mine. I like old college campuses-I feel spirits about.

donjusko
09-25-2002, 04:08 AM
Ok,

Here's what I would do to make acrylic gesso and PVA more oil paint receptive.
Reduce the strength and viscosity of matt acrylic medium by 3/4, add a little zinc and titanium white pigment, chalk dust and marble dust, a lot more marble dust. Then when it's dried a light sanding will expose the marble and hold the oil paint for you. Wiping down the dried gesso with isopropyl alcohol would make the top micro layer of medium thinner, but still sand it before you use it.

A neutral PVA or acrylic medium, add marble dust, chalk and white pigment. Make a Marble PVA gesso paint water based for oil. Much better than the one size fits all acrylic gesso.

Really, your are a lot better off making a soluable glue ground and sticking it to a glue sizing.
And if you can't do that, buy an oil primed canvas, they got soul.