Gesso coating or paint primer?

[bestof]

Originally Posted by Michael24

. (Paint companies like to call chalking *self-cleaning*)

Michael Skalka

Hehe-

I'm wondering how are the paintings by Keith Haring on tarps doing? I saw some vinyl on sale at the fabric store at bought some, thinking the paint wouldn't stick, but it sticks really well and I like the smooth surface. It's 12 gauge(kinda thick). I'm just wondering, will it start releasing gases and deteriorate soon or will it last at least a few hundred years? I know mylar is used to preserve comics and baseball cards, but I'm not sure of the difference between that and vinyl.

Thanks for such a great thread!

[Michael24]

Originally Posted by bestof

Hehe-

I'm wondering how are the paintings by Keith Haring on tarps doing? I saw some vinyl on sale at the fabric store at bought some, thinking the paint wouldn't stick, but it sticks really well and I like the smooth surface. It's 12 gauge(kinda thick). I'm just wondering, will it start releasing gases and deteriorate soon or will it last at least a few hundred years? I know mylar is used to preserve comics and baseball cards, but I'm not sure of the difference between that and vinyl.

Thanks for such a great thread!

I assume you are using acrylic paint? Sorry, vinyl is not on any of our list of painting surfaces. Its pretty active chemically. To get plastic to be fairly rubbery it needs plasticizers. They maintain plastics' flexibility. I am not certain but a commercial vinyl may not have been made for long term use. So its not so much the gasses as it is the components that make it flexible. Look up via Google the Barbie Doll mess. The plasticizers that go into making Barbie soft and plyable after 20-30 years are now making Barbie a gooey sticky mess.

Michael Skalka

[gogodi]

Originally Posted by Michael24

With so much emotional energy exhibited, its a wonder if anyone has the strength to paint after that!!


Commercial house paints, as stated in a previous post, is a suitable product for houses. Using them for fine arts... well you do that at your own risk, and perhaps at the risk to the potential buyer of your artwork.

House paints in many cases have acrylic and styrene blends. The chemistry is complex. However, the styrene is the culprit that contributes to short-term degredation. Its the resin used in cheap student grade paints.

I can't stress how complex acrylic paints are in their formulations. They are a marvel of modern polymer science. Serious artists paint companies put forth a tremendous effort to use the right acrylic resin mixtures with just enough of the additives to make a product that has flexibility without being rubber-like, hard without being glass-like and a rheology that provides good working properties. That's without the addition of pigment!! That adds a whole other level of complexity. Too much pigment and it becomes a dry coagulated mess, too little and it has weak tinting and covering strength.

Commercial house paint is formulated with the same precision for its intended purpose. It needs to expand and contract, retain pigment and binder integrity under varying weather conditions and be easy to apply. (Lots of other factors go into house paints as well)

House paints are made to have a moderately short life span. The binder breaks down even with a UV blocker. The pigment starts to come off in what we call chalking. (Paint companies like to call chalking *self-cleaning*)

Here is my point. If you want to mess around and practice painting or do some preliminary sketching using house paints that's fine. But, when foks in galleries and even here on WC talk about paintings selling for several thousands of dollars, I'm sorry, but I don't want to buy a work of art for that price make from house paint.

You can site Pollock all you want. His works are falling apart and need a ton of conservation. But as a cultural icon, he has been deemed to be worth saving.

Without analysis who is going to tell a buyer that the painting they are buying is loaded with styrene which will break down and fail. It may look like an acrylic painting made from artists grade products, but it certainly won't age the same with these commercial products.

If you paint only for yourself, then only you care how your paintings will last. I think it is an artists responsibility when making the transition from painting only for personal pleasure to entering a contractual sale, to provide a work of art that avoids materials that contain inherent vice. I think the responsibility increase as the sales price increases.

Michael Skalka

Very interesting discusion, Right now I am painting for myself in order to learn what to use and how. I guess you are right about use the right material in order to have a good solid achievement that can last for years to come. I will soon start to use better material also. Thanks for all the advice I really got enlighten.

Thanks a lot evrybody

G. Art-Vie, Quebecoise

[bestof]

Originally Posted by Michael24

I assume you are using acrylic paint? Sorry, vinyl is not on any of our list of painting surfaces. Its pretty active chemically. To get plastic to be fairly rubbery it needs plasticizers. They maintain plastics' flexibility. I am not certain but a commercial vinyl may not have been made for long term use. So its not so much the gasses as it is the components that make it flexible. Look up via Google the Barbie Doll mess. The plasticizers that go into making Barbie soft and plyable after 20-30 years are now making Barbie a gooey sticky mess.

Michael Skalka

Yes, acrylic. I looked into it a bit more and everyone says vinyl stinks for longevity. Polypropolene is used for archival purposes(I was told it's inert)so I may try to paint on that.

[Pilan]

So many posts here I can't seem to find what I need.

If a person is using 1/4 inch birch panels for painting support, what would be the preferred priming method and materials?

Thanks
Pilan

[Einion]

Hi Pilan, is this birch plywood or a plain birch board? I’m guessing it’s ply but you never know Also, are you painting in oils or acrylics? Some priming methods are equally suitable for either.

Einion

[Pilan]

good questions. I forgot to say !

1/4 inch I am supposing it would be panel. but then can you purchase 1/4 birch board? If so, I would purchase board at lowes home improvement store if they sell it. I have always wanted to paint on birch. I had in the past twice and liked it. The panels I purchased was already made and pricey so I want to cut my own.

Is the method for priming different for board and panels? Can you give me both methods, please? Also, I paint in oils.

Thanks,
P

Originally Posted by Einion

Hi Pilan, is this birch plywood or a plain birch board? I’m guessing it’s ply but you never know Also, are you painting in oils or acrylics? Some priming methods are equally suitable for either.

Einion

[Einion]

I think it's likely this is plywood and not a solid board at this thickness, just wanted to be careful as I don't know what's available in the US. By the way, as a general term panel just means a board, in the old days it referred to solid wood (usually quite thick) like the Mona Lisa is painted on, these days it often refers to plywood but it can mean hardboard or even MDF. Plywood is a lot more dimensionally stable than solid wood panels so in some respects is much better, although the glues that bind the layers together do degrade over time (decades). FWIW I think good-quality hardboard is a better idea for the long term if this is a concern at all, they don't contain added glue like MDF and plywood so, appropriately primed, should last very well.

Anyway, for oils there are a couple of options in terms of prep. Regardless of the method you use you should first lightly sand the face of the board that you want to paint on with medium-grit sandpaper, to scuff the surface and remove any minor surface contaminants.

If you don't have a problem with painting over an acrylic primer, buy a good brand of acrylic 'gesso' that is intended for both acrylic and oils and check to see if they recommend sizing first, most don't and if the primer layer is thick enough it's really not necessary. If you're cautious you can do it anyway, in which case I would use either PVA glue or acrylic medium.

Apply the primer by brush or roller in a number of layers, applied at right angles to the last (helps prevent brushmarks building up if you use a bristle brush). You don't have to sand between layers but if you want a smooth finish at the end of the day a light sanding to knock the high spots down is a good idea. I would use about five to seven layers of 'gesso', three is about average I think; a lot depends on the consistency straight from the container, how thickly you apply each layer and whether you thin it. Once you've finished priming you can sand it smooth if you want a flat surface, if you like the brushy texture just leave it to dry. Although acrylic looks and might feel dry in quite a short time I'd leave it a day or so before beginning painting, particularly if it's humid.

I personally feel you should prime the back and all edges of boards for various reasons but mostly to isolate it as much as possible from changes in humidity. This isn't as much of an issue with plywood as it is with hardboard though.

If you want a smooth, flat surface I recommend wet-sanding as you don't have to worry about dust and it's a lot less effort than using normal sandpaper (unless you use a palm sander of course ) but you need to be careful of the water if you have only primed the face of the board. Remember that oils need a good degree of tooth in their ground to bind to properly so don't go overboard on the sanding. With acrylics you can paint on a surface wet-sanded to P800 but this is almost certainly too smooth when painting in oils, so 100-200 grit is maybe the finest you should go – the final finish should have a definite drag if you draw a fingernail over the surface, something like an egg shell.

If you want to go with something more traditional, you can size the panel and then use a lead/oil primer. Most any Lead White/Cremnitz White bound in linseed oil should be appropriate. The traditional size is 'rabbit-skin' glue but I would recommend PVA or acrylic medium. There are a number of threads in the Oil Painting forum on applying oil grounds from people more familiar with it than I am but I wouldn't recommend sanding the surface.

Finally there's also true gesso to consider although I don't think it's a good ground for oil painting myself even on a rigid substrate. If you want to try it, again I'm sure there are threads that deal with how to do it and a number of the painter's guides give detailed instructions (it's pretty labour-intensive).

Einion

[Pilan]

Thanks Einion, I printed this out.

P

[bowdog]

wow,

Here I was thinking I was sneaking around behind the Masters of Painting, when all along there's all these folks struggling with the same questions I have.

I've been battling with myself for weeks now about the gesso vs primer question, and it's painful to hear primer is getting beat down so bad.

I keep seeing this guy in overalls down at the Paint Factory scratching his head as he fills up all those big primer containers and then switches to the little half pint gesso containers - same paint, different bottles, and a dicotomy of prices.

Anyways, thanks for everyone who took the time to write in on here.

[hovawart]

Priming: The act of creating a sealing layer on a canvas or support to form a stable foundation for your painting. It seals the support from the paint layer. In oil painting this is important because oil paint will oxidize canvas and destroy it over time.

Michael Skalka, National Gallery of Art, Wash. DC[/quote]

Does anyone ever use shellac, a natural product made from bugs?

[Einion]

Originally Posted by hovawart

Does anyone ever use shellac, a natural product made from bugs?

Shellac is used by some artists as a size on board materials (it's brittle, so a poor choice for canvas). This would be underneath the primer layer in most people's prep method, if used.

Einion

[gunzorro]

Hone uses shellac as a sealer for mounted paper before painting on it with oils. He uses no additional priming.

[Dave Hawk]

hovawart; I use shellac but only for french polishing and sealing a new piece of mahogany before finishing. Over time the shellac will yellow greatly and is thought of as a galery finish and not much use for it these days. I've cleaned old oil painting and found some have a shellac coating on them which is easely removed.