Mesh size?

I'm looking at doing my first BIAB and want to KNow the mesh size for the bag.Can the mesh size be to small?

Just get the five gal paint strainers from your local home improvement store. They are fine enough. Double bagging isn't a bad idea especially since they come in two packs.

I have these high temp mesh water filters at work that are 200 micron that I think would work is why I was asking

Go to the fabric store and get a couple yards of polyester voile material.
It is about $3.00 per yard. Have someone who can use a sewing machine make the bag so it will fit just right on your mash/boil kettle. This is the very best material to use as the mesh is very fine and the finished bag is extremely strong.
It helps if you can incorporate 4 nylon straps at the top of the bag for hoisting it out of the kettle.