In the "Don't call me late for dinner lightest board challenge"
James and I decided to try building boards out of 1 pound density foam. There are some significant challenges with this (such as attempting to shape it is much like trying to sand a wet noodle
). That aside, the construction itself is rather interesting.
One of the issues with EPS that POLYU doesn't share is that the board must be sealed prior to laminating. I'm stealing a page from sfoam's website (makers of eps blanks):
EPS blanks must be sealed properly before laminating. Resins without micro-balloons added, will soak deep into EPS foam, making it difficult to properly wet out laminating cloths. This means you can use much more resin than
is necessary. This creates a heavy board, trapped air and pinholes; and loses the advantage of a lighter blank.
Although there are other methods of sealing EPS blanks, sFoam™ recommends using the "aviation" method of sealing structural foam.
Mix one part (by volume) micro-balloons and one part (by volume) epoxy resin/hardener. Squeegee this mixture over each side in turn, be sure to use a minimal amount to make a dry coating (try making a final hard pass with the
squeegee). Make a final hard pass over the stringer when you finish the sealing, to remove the sealer from the stringer.
Let side cure, repeat on other side.
Use a "cake frosting" consistency of epoxy/micro-balloons to fill in any pukas or dents left in the blank ( this can be done before the initial sealer is fully cured. )
When both sides have been done and cured, dampen a clean cloth with de - natured alcohol and wipe the blank. Then lightly sand the blank with 100-150 grit sandpaper and laminate.
Using the micro-balloon mixture keeps the epoxy from migrating too deep into the foam, yet insures a total epoxy-to-epoxy bond with the laminate and a strong bond to the foam.
Hybrid Mode
