To tidy things up. I've put your comment here, Dave, and deleted the other thread.
Dave Rogers wrote: Having just sprayed my 90mm f86 sabre silver I can help you out here. I did a lot of testing before finally plucking up courage to spray the foam. Basically if you hold the spray can too close the foam will melt from the propellant in the spray can. However if you spray the foam outside In the open air at a reasonable distance the propellent is dispersed in the air and only the paint lands on the foam. Hey presto no foam melting.
Another helpful bit of advise to be very sure is to paint the surface of the foam with a layer of pva glue first, let it dry then spray away.
Colin...the reason Dave could not reply is because you had put the original message in - Main forum - support. I'm guessing that this category is for Phil Ford only, since we do not get the reply options. I've moved your message to a different category and it should work now.
Mike