Hi grandpopswalt
That sounds like polyfiller or spakfiller spelling?? but I thought the pre mix exterior stuff was grey in colour not white.
Get the powder and mix it with water and a little pva that will give the nice plastic mix that will not crack as easy once dry. paint with exterior finish of choicee
regards John
Water Putty has also been used to seal foam models with a great degree of success. Although youd most likely have to sculpt the details into the putty before it hardens, only using the foam as a support structure.
G.R. february 1995.Article by Jack Verducci.
Walt,
I live in England and I have found that what we call masonary paint provides good protection for styrofoam. I also use clear silicone filler as an adhesive for joining the stuff.
Regards,
John
Used white styrofoam in our garden railroad building a via duct . Use 5 sheets laminated them together with construction glue stagering the joints and painted with white cement for a cement finished viaduct. Heavy rain water run off flows through with no damage. The only time we have had to perfform any tough up is when a tree branch has fallen on it. Has been in the garden railway for over 3 years and does not crack when the below freezing weather comes and when the sun shines on this structure either.
Mikadosurp