Modeling paste & oils over Acrylics

 

Modeling Paste and Oils Over Acrylics

Dear David,

I have recently begun to experiment with a heavy modeling paste under my oil or acrylic paintings.  As the work often becomes quite large this adds to the general supply cost.  I currently work on canvas with three hand-brushed gesso coats, the modeling paste becoming the fourth coat.  I have used several jars of Golden paste and also just tried the Loomis brand, DeSerres.  Either seem to be fine, I just wondered if there was something else "out there" that I should know about? I enjoy reading articles that you write when I see them-do you have a central location for previous FAQ's?
Thank you for your time David.  Sincerely, Susan

Hi Susan,

I am not sure what you are asking about the paste.  I can tell you that modeling paste, or molding paste as it is sometimes called, is not very flexible like the gel mediums used for making texture and therefore more likely to crack when used on canvas... I always mix some gel medium with my paste when using it on canvas.  If you want to save money, try the Tri Art stuff and buy in bigger quantities. 
Bye for now, David

 

Hello,
I am wondering about the long term viability of oil paint over an existing acrylic painting.  I have already done it, using thin oil paint layers, and everything seems fine.  But I am wondering about the long term.

Thanks,  Emilia

 

Hi Emilia,

That is a good question, and I get asked this often.  Many painters use an acrylic underpainting for their oils. 

Oil and acrylic paints don't blend or adhere very well to each other permanently.  Because acrylic paints are porous and oils have a shinny non porous surface, oils will adhere better to acrylics than vise versa.  So painting oils over acrylics is better than applying acrylics over an oil underpainting, at least in the short term. 

Problems may arise over time because oil paint becomes increasingly hard and brittle with age and acrylic paints stay soft and flexible indefinitely.  If there is any movement of the support (canvas), this will cause the layers to separate and the oil paint will crack. 

Imagine if you were to paint the oils onto a plastic bag and then you stretch the bag once the oil paint has dried.  This is an exaggerated example, but you get the idea. 

Because of this, it is much safer to paint oils over acrylics on a rigid surface, like hardboard, rather than a flexible surface, like cotton canvas.