What causes flex coat part A resin to turn milky white, and form small
lumps . Has happened to me twice. This morning I used a lighter to
heat the finnish and the small lumps disappered. I quess this means the
resin is no longer good!

No, it's still fine. That's just the resin crystallising from being unused over a long time, and subject to temperature variations in storage. As you saw, it is restored to its liquid state by heating. Gently warming the bottles in a microwave or in a little tub of warm water will get it back to a fully usable state.

Don't heat it too much (nix the lighter), and before you mix give both components a chance to cool off a bit. The extra heat accelerates the curing process when the components are mixed. Heat them, let them cool slightly, mix, then spread out on foil. It'll be fine: the same thing happened to me last week.

Like Ted said!!

Mike (Southgate, MI)
If I don't want to, I don't have to and nobody can make me (except my wife) cuz I'm RETIRED!!

I've had to heat mine several times to get it back to useful condition. LIke the others said, it won't hurt it a bit. I've yet to see anything harmful or wrong with any of the epoxy resin I've heated to return it to good forum. It works just it did originally.

Watch out for any flecks that might not get melted back into the mixture!! I had some one time that didn't go back into solution and had little crystals turn up in some of my wraps. Turned out to be those crystalized flecks. Heat the epoxy resin long enough to make sure EVERYTHING goes back into solution.

I had a similar problem some time ago. Since then I set epoxy up on a block of wood;
then turn a hair dryer on it. I do this every time; even though my shop is heated in Winter'
and cooled in Summer. It seems to keep the epoxy in good shape; and fluid. I do this
first; and let the dryer run while I'm setting up rod dryer; and making other preparations.
I find this step useful for other tings too; like glue; varnish; paints; etc.