Creative Resources Distribution has done some strength
testing of Jesmonite in various configurations. Jesmonite is intended to
replace polyester resin as a non toxic and non-flammable alternative for
casting and laminating.
Note that Jesmonite can also be used to laminate on the
inside of latex or silicone moulds - a Jesmonite Thixotrope additive is
available to produce a gel coat for the initial layer.
Click the pictures to the left to see the bigger
Jesmonite Test 1
A pattern was drawn on an A4 sheet of paper, cut out, and
glued with paper glue to make a curved item. This method for construction
was chosen in order to test the strength of the Jesmonite which was later
stuck to it, rather than the strength of any other structure.
One layer of Jesmonite, mixed as directed, was painted
onto the paper along with one layer of standard 30gsm fibreglass surface
tissue. After about 20 minutes this was hard to the touch and allowed the
next stage to be completed.
The next layer consisted of overlapping standard 600gsm
fibreglass chopped strand mat laid up with more Jesmonite mixed as directed.
The outside of the item was also coated in Jesmonite,
mixed slightly thicker than directed, and the item was trimmed around the
After 24-48 hours, the Jesmonite is fully hardened. The
strong enough to stand on and extremely impact resistant. Although not quite
as strong as a fibreglass piece made with polyester resin, Jesmonite is a
very suitable alternative where a non toxic and non flammable product is
Watch this YouTube video of the impact and strength
tests on the item:
Jesmonite Test 2
For this test, Jesmonite was laid up onto a piece of A4
paper with one layer of 30gsm surface tissue and one layer of 600gsm
fibreglass mat. The item was then trimmed down to a piece roughly 5cm x
Various weights have been applied to the item while it is
propped between two cups as shown:
1) A two litre bottle of water, which weighs 2Kg was placed
in the middle of the item while the ends are suspended on the cups. As you
can see the item has flexed a little.
2) Next a 4Kg kettle bell was placed on the item in the same
fashion. There is a little more flex to the item.
3) An 8Kg Kettle bell is placed on the item. You can see
there is a lot more flex to the item, but it did not crack or break. It also
returned to it's normal shape after the weight was removed.
In conclusion, Jesmonite is a suitable material where a non
toxic and non flammable product is preferred, for movie prop construction,
costuming and model making.