I have purchased several ironon patches. I have had a bit of a problem with them completely sticking. I am having to heat them quite a bit to get them to stick. This can cause some change in shape. What temp do you recommend for application? Also what is the clear backing? Hot glue? I’m just wanting to keep the integrity of the shape. The last order some beads had holes in them before application and others (pearl look) melted when heating to apply. Any advice?