I'm making a few potholders and trivets. The only batting I have is warm and white. How many layers of batting should I use?

I've heard that 2 layers are good. Used to make crocheted ones from yarn, and just the 2 layers of yarn seemed good enough. With fabric, however, you want to make sure to give enough distance between you and the heat.

I usually use two layers and a piece of that silver stuff that they use on ironing boards.

That's what I use, too!

I have seen raw-edged trivet/pot holders created with many layers of fabric, perhaps some denim thrown in (we country people really do like our denim <g>)
one suggestion on the board was to use a couple of towels.
The potholders I remember seeing were stitched about 1/2" around all the sides and then a simple x through the middle ... or, I would probably do the x first, and then anchor things around the edges. No binding, no turning ... and, my mother washes things a LOT. These simple potholder/trivets have held up many years <wave>

I use a layer of warm and natural and a layer of insulbrite, plus the back and top.

simple quilter

Yep, two layers with Insulbrite does the trick. You can use old towels too.

Two layers for me too.

Two with insulbrite between them or three warm & natural if you don't have insulbrite..

Thanks for the tips. I decided to go with two layers. Hopefully it'll work out.