To make sure I fully understand your problem: 1. You apply LPI solder mask onto ground planes which have through holes. The ground planes are copper and the LPI mask is applied/processes/cured, as normal. 2. Next, you apply a temporary solder mask (by squeeze bottle or screened) onto the through holes and dry/cure. 3. You run the boards through normal wave solder operation and and remove the temporary solder mask with a hot water spray. 4. Afterwards, you see "lifting" of the solder mask around the through hole areas which extends for 5-30 mils. If this is your problem, I think I may know what is causing it. Many of the water soluble temporary solder masks contain ammonia/amines to make them water soluble. These ammonia/amines are alkaline and LPI solder masks are sensitive to alkaline materials (they can be stripped with high temperature sodium hydroxide solutions). The ammonia/amines attack the LPI solder mask at its weakest point (the bond to the copper) and cause it to lift. Possible solutions to your problems might be: 1. Check the preclean of copper before solder mask to make sure the bond is optimum. An anti tarnish might help here. 2. Make sure the LPI mask is exposed properly, not over developed and cured properly. 3. Try to apply and cure the temporary mask quickly and then run the boards through the wave solder quickly and remove the temporary mask. This phenomenon is time dependent. Especially make sure the temporary mask is cured quickly. The solvent/ammonia/amines in the temporary mask working on the solder mask can be very aggressive, so at least get rid of the solvents. 4. Change to a non ammonia/amine based temporary mask. There are many available that do not contain these materials. Hope this helps. Larry Fisher Allen Woods & Associates