I do not store pressing
I warm press by soak both mirror and lap.
I use an iron to open channels.
I don’t like leaving cerox on the glass.
I agree with Danny. It doesn't take long to warm press a lap back into contact. If you leave the mirror on the lap, the channels will close up and you risk getting the mirror stuck to the lap. If that happens you can damage the lap getting the mirror free.
The secret to mirror making is understand how the contact of the lap effects the figuring. I have seen ATMs fight for years trying to figure a mirror because they don't understand this concept. If you want a spherical surface, that means that lap must wear the optical surface uniformly. That requires uniform contact and that require equal area of contact. This means the facets and the channels need to be uniform in size across the whole lap. A small difference will lead to zones. Once you understand this you'll have no problems making perfectly spherical surface. When it comes to figuring a parabola, the classic W stroke works on the assumption that your starting with a spherical surface and have a lap that has uniform contact. The stroke causes control wear of the surface to turn into a parabola. If you don't have a lap with uniform contact, the W stroke doesn't work and you most likely dig a hole.
So if things are working and you stop and let the mirror sit on the lap, the lap is changing shape, ie the channel are start to closeup. So try to pick up were you left off and the next time you test, the figure as got away from you and your wondering what is going on ? ! So what I do is just cover the lap with food wrap, and when I start up again do a mild warm press and make sure that the channels are still open to same width all across the lap. I can control the figure and I don't get surprised the next time I test it.
Edited by DAVIDG, 12 December 2018 - 04:20 PM.