acrylic underpainting

[sease]

i apologize if this has been discussed, i searched and didn't find anything.

i was wondering if it's a bad idea to do an acrylic under painting that you layer over with oils. i mean, i've been doing it, and it works out fine in the short term, im wondering if this is going to cause problems later on. are there any real disadvantages to this? thanks.

[Elwell]

Don't worry about it. It will be fine in the short term, and in the long term, if there are any problems (a) you'll be dead, and (b) in the unlikely circumstances that people care enough about your work to keep it in good shape, they will (EVERY SINGLE painting you see in a museum collection over, say, seventy five years old has had some sort of conservation work done on it).

[Grief]

most gesso is acrylic based, which is used to prime raw canvas.

once any acrylic based medium is dry, it is waterproof.

just make sure that the medium is thoroughly dried before adding any oil based materials on top.

as elwell said, it'll be fine for your lifetime.

[DavePalumbo]

yeah, so long as you're not oil priming your surfaces you'll be fine. Personally, I'm a big believer in the acrylic underpainting

[StupidIsAsStupidDoes]

About a year ago, I was at an art show, and I met an oil painter who "didn't believe in acrylics." His rationale was that acrylics have a tendency to peel away from the surface over time. He gave a thorough explanation of this theory (acrylic is a relatively new painting medium, and hasn't been around long enough to test the long-term effects). Personally, I think it's irrational. A lot of artists give countless reasons for being adamant about using oils exclusively; but companies like Golden strive to test the permanence and durability of their pigments and mediums. Although they provide a disclaimer saying that they still don't know the long-term results, acrylic is a tested and true medium. And unlike oil, acrylic is more versatile. It is much less likely to crack (ie there's no fat-over-lean rule), it doesn't yellow, and it contains ultraviolet stabilizers, which ensures superior permanence in the pigments.

So, each medium has its own strengths and weaknesses. Personally, I prefer acrylic because of its pigment range, colour brilliance, nontoxic mediums, and fast drying time, which makes it a much more forgiving medium, and perfect for layering and glazing (although this can also be seen as a disadvantage; depending on how you work). I see nothing wrong with using it for an underpainting, but I will say this: DON'T use a gloss medium. One of the reasons acrylic gesso is great for priming the surface is because of the added chalk content; which makes it grittier, and gives the oil something to cling to. If it's glossy, the oil will have poor adhesion. Therefore, only use matte medium/gel.

[Ilaekae]

To add for completeness--there is some evidence that acrylic "gessoes" on stretched canvas, especially larger works, may cause oils to crack more because the canvas/acrylic combination is much more flexible and mobile than the oils are when thick and dried.

[StupidIsAsStupidDoes]

I've never heard of that, especially since the gesso actually helps stiffen the canvas and stretch it further. But if you want to play it safe, I'd suggest stiffening the canvas with GAC 400 before applying the gesso (much like how the old masters would prime their surfaces with rabbit skin glue).

[Chris Bennett]

I've never heard of that, especially since the gesso actually helps stiffen the canvas and stretch it further. But if you want to play it safe, I'd suggest stiffening the canvas with GAC 400 before applying the gesso (much like how the old masters would prime their surfaces with rabbit skin glue).

Something like this is better than Rabbit Skin glue because it isn't 'lifted' again by the application of wet arylic gesso. That said there is nothing quite like a real gesso ground made with rabbit skin glue and whiting.

[Verdaccio]

That said there is nothing quite like a real gesso ground made with rabbit skin glue and whiting.

QFT Chris. :)

Nothing much to add here, in total agreement. I have done a number of paintings with acrylic underpaint and it works fine.

Plastic is forever.

BUT...if you are concerned about adhesion of the oil layer to the acrylic layer, it never hurts to rough up the surface of the underpainting with a bit of sandpaper before you start in with the oils. I typically do this as it aids in a mechanical bond. I wipe in a thin thin thin coat of oil and the scratches from the sandpaper almost disappear and I can then proceed in with the oils.