There are several solutions to this problem. Yes, it is difficult to get acrylic paint to stick to oil-based primer or paint, but all is not lost.

There are several products on the market just for this problem. One is called Liquid Sandpaper. The others are similar. Ask in a paint supply store. You "paint it on" and let dry. They you can paint the acrylic over it.

If you don't have access to the chemicals, you can always go over the oil-based paint or primer with medium (100 - 120 grit, or so) sand paper LIGHTLY, and then vacuum the wall to get the dust off. You are NOT trying to remove the oil-based product, just roughen it bit. Then paint with the acrylic.

Liquid Sandpaper stinks and you need PLENTY of ventilation, but it much easier on the hands, arms, and shoulders than sanding.

By the way, next time, I recommend a white acrylic primer that has been tinted green, rather than using pure white. It is easier to get an even coat if you put green over green, even if the two are not perfect matches.

By the way, next time, I recommend a white acrylic primer that has been tinted green, rather than using pure white. It is easier to get an even coat if you put green over green, even if the two are not perfect matches.

that's a very good tip. the primer wasn't just mean for the green area though, that's why it was pure white. shoulda spent the extra $10 on some green tinted primer. :)

Since we're on the subject of home-made green screen, allow me to ask this related Qs.

Which is better, cloth or paint?

--- Cloth seems better for it would be less reflective---and what kind would you recommend? But it can get pricey, and I'm not even talking about buying the "real" and way expensive industry stuff. Just fabric store.

--- Paint is cheaper and one can fix areas when needed. I can't paint my walls, but I can get some plywood board and paint that.

In either or both cases (and again, think low budget DIY) ...

What is the best way to light such home-made greenscreens?

I realize that much of tboth of the above depends on how one works in post, too, for one could argue both ways on which is easiest do edit due to lighting, etc.

Your thoughts, experiences, etc.?
Thanks.

Q: Paint or Cloth?
A: Painted things rarely get wrinkes but don't fold up. If it's permanant painting is better, you could even build a seemless cyc.

Q: Best way to light a screen?
A: Daylight fluros, Kinoflo if you've got lots of dollars. Cheaper way, buy existing el cheap fixtures and replace the iron ballasts with electronic (aka HF) ones and use tubes designed for the job. Why daylight? Well it seems that cameras are natively daylight, probably a very small factor but everything helps.

Bob.

Although cameras might be natively balanced for daylight I think this link gives a solid http://www.bluesky-web.com/greenscreen-6.htmreason for 5600K lighting[/link]

In the U.S., Home Depot has good 2x40W "Heavy Duty Worklight" workshop fixtures with electronic ballasts, with reflectors suitable for video work (work well and are easy to gel), for abt $40.

They also sell Philips high-CRI tubes for about $6 each (size T12 for above). The daylight tubes have a CRI that is as good as KinoFlo tubes, the warm white 3200K tubes hit 85 which is still acceptable, especially for lighting greenscreens.

I really must be going senile. I'd read that article some time ago, excellent stuff, and then somehow had the 'daylight is better than tungsten' thing in my head and got that mixed up with something else I had more recently been pondering.

Bob.