Casein over ET

[JeanM]

I'm aware that some folks apply ET over an underpainting in casein. But, I'm considering painting in casein on top of an ET. Would this work? Or, would oils be better?
Thanks for any help.
Jean

[turlogh]

I'm aware that some folks apply ET over an underpainting in casein. But, I'm considering painting in casein on top of an ET. Would this work? Or, would oils be better?I don't know. I've never heard of cassein being used over ET. The question is whether cassein will bind properly to an ET substrate. What properties of cassein and ET make you want to do this?

Oil has been used over ET since the Renaissance. The two mediums compliment each other beautifully.

[JeanM]

[What properties of cassein and ET make you want to do this?

David, I should have stated my reason for wanting to use casein. I would like to completely hide the underneath ET and oil takes longer to dry.
Jean

[turlogh]

I would like to completely hide the underneath ET and oil takes longer to dry.
So why not just paint with cassein?

[dbclemons]

Casein can safely be painted on top of tempera.

[JeanM]

So why not just paint with cassein?

David, I may end up using the panel to make a casein painting, or maybe an oil painting. But I think the casein can be used more easily than oil to obscure the underneath ET. And it will dry more quickly because it's leaner. This is an experiment for me. I also wonder if after the casein dries I could use ET again.

[Dennis H]

Jean,
Are you trying to simply cover a passage on your tempera painting with an opaque area, or do you want to cover the whole thing and start fresh, so to speak? If it's the latter, you'd probaby be better advised just to scape off the tempera paint and even sand the gesso somewhat, then start a new casein (or tempera) painting. You'll be better off with some adhesion to the gesso instead of layering over old paint.
If you, instead, are trying to do the former -- obliterate, or erase, some area of paintwork you don't like -- why not just selectively scrape away or sand down the parts you want to cover?
Dennis

[JeanM]

First, I would like to say thanks to all of you for your replies to my question. Your responses have given me good information. So far, I haven't done anything to the panel due to other commitments.

Dennis, yours is tha latest response. Yep, I do want to cover the entire panel. I was trying to come up with an quick and relatively easy solution. Scraping and sanding sounds like not only work, but a way to damage the panel. Actually, it the former. I'm lazy.
Thanks everyone.
Jean

[Dennis H]

Jean,
I really don't think it will be too hard to take it back to the ground. Depending how long the tempera has had to "cure" it may scrape off pretty easily. But, some 120-grit sandpaper to start, followed by finer grades should erase the painting pretty easily without scoring the ground too badly. You might lose a little gesso around the edges of the panel, though, and elsewhere if the ground is thin. If you decide to scrape it off, a good flat piece of metal, like a putty knife, will work wonders. Or a glass slide for a microscope specimen. You probably want to file off the knife's corners to round the sharp points so they don't gouge your panel. Rob't Vickery writes about using those old, flexible, double-edged razor blades to scrape away mistakes, but I haven't seen any of that type blade since the late 60s - early 70s.
If you whitewash over the existing painting with casein and start a new image, there's a chance the underlying painting will eventually start to show through. You find such "pentimenti" in old temperas and even oils as the paints turn more transparent over time. Also, alternating layers of different types of paints may prevent good adhesion. I'd hate to think that your new and improved painting started flaking because of problems underneath it.

[JeanM]

Dennis, you have certainly mastered the art of gentle persuasion. You have me convinced that removing the ET is the best way to proceed. That's what I'll do. Thanks for your persistance.