The basis of a great spa is a great spa shell.
Our Thermobond shells use the best of materials and processes to ensure
their strength and durability match the best that the world has to
offer. The Infinity shell is produced using an 8 step, 4 layer process
that is second to none.
American made, Aristech acrylic is kept in a climate controlled
environment to avoid moisture penetrating the acrylic surface, as
is the resin and fibreglass used in the shell construction. When
required, the acrylic sheet is hand sanded to assist adhesion to
the fibreglass layers.
The acrylic sheet is heated in a zone controlled oven before
being vacuum formed into the spa mould. The zone controlled heating
ensures the thickest possible acrylic shell is formed. This method
of zone heating is only used by premium spa manufacturers, as it is
the most precise method of acrylic forming available
The formed acrylic shell is then sprayed with pure vinyl ester
resin. Vinyl ester resin is the industry’s best quality resin. It
is also the most expensive resin and therefore, many manufacturers
do not use it. This resin gives the acrylic a permanent water seal
to eliminate the chances of de-lamintation. It also provides a base
for the following layer to adhere to.
The shell enters a temperature and humidity controlled curing
oven. This process is crucial for resin and fibreglass
manufacturing as it ensures that any moisture in the resin or shell
evaporates and allows the resin to cure evenly over the shell,
creating a permanent water seal.
The shell is sprayed with its 2nd & 3rd layer – marine
grade, pure polyester resin and glass fibre. This layer bonds with
the vinyl ester and acrylic shell to ensure permanent adhesion. It
also provides reinforcement to the shell, along with the following
The spa re-enters the curing oven for a second pass to cure the
polyester resin & glass.
The lip of the spa and crucial weak points are strengthened
using hand layered fibreglass sheets. At this point, timber blocks
are fibre glassed onto the spas shell to provide fixing points for
the frame and equipment
The shells 4th layer is sprayed using GP resin mixed with stone
powder. This layer literally sets like concrete to give unsurpassed
shell strength. The torsional rigidity that the stone powder gives
the resin, means that our spas do not have to use timber supports
under stress areas that many spas rely on