|EPS must be laminated with epoxy only.
Styrene resins used on urethane blanks will melt EPS foams. There
are many epoxy resin/hardeners now available specifically designed
for surfboard manufacturing. Please check our '
Useful Links ' in the FAQs section of this web site for epoxy.
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
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
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.
Epoxy fill, sanding and finish coats offer the
highest strength and better UV resistance, although some epoxy
resins may require more work to sand.
Polyester resins can be
used on top of epoxy laminations; as fill, sanding and finish
coats, but just do not let these resins come in contact with
raw EPS foam.