Technical Information

The material we use is a polyurethane binding resin. Epoxies are not
UV resistant and literally break down under UV. We stopped using
epoxies over 10 years ago because they were failing all over the
place. This breakdown can be seen in the very beginning by chalking
until the actual pebbles start breaking out. It usually took about two
to three years before they started to break up and individual stones
started to break out within a short time the whole area started to
have holes in it.
As you are also aware epoxy discolours over time and turns yellow.
This is more noticeable on whites which turn yellow and greys that
start to turn green with the yellow discolouration.

Further more properly cured epoxy is brittle which has a number of
disadvantages in external applications. Turning forces exerted by the
wheels turning on a vehicle can literally chip the loose stones out
with a brittle binder like epoxy. Polyurethane binding resins although
softer are more flexible and tend to give with the turning forces
instead of resisting them. This flexibility does not show any
disadvantages as regards compression strength and its strength is more
in the thickness of the material which for Polyurethane binding resins
is between 16 and 20 mm depending on the kind traffic the area will
receive.

Our polyurethane binding resins have many advantages over epoxy
binding resins. This resin has a number of advantages making it
perfect for external and internal areas.
* UV Stable (Spectrabind UV)
* Long Trowelling Time
* Low foaming
* Trowels easily
* Hard yet flexible (Can be laid on tarmac externally or wooden
substrates internally)
* Easily mixed
* Does not require exact mix ratios as with epoxy
* Controllable setting times 1-8 hours dependent on temperature with
no affect on its UV stability
* Does not chalk and become brittle under UV as with epoxy binding resin
* Available in 7.5kg sets or 25kg 200kg and IBC containers

SUDwell P.U.4844 UV is amongst the most stable of UV binding resins
available on the market. It is more flexible than our P.U.3776. This
resin must always be mixed evenly with the dry aggregate. Care should
be taken not to use resin rich scrapings from the mixer or wheel
barrow. After a few mixes these should be discarded. Any pooling or
ponding of the resin may cause foaming which will result in an
unattractive finish. This resin is ideal for all aggregates but
especially lighter colours and blue or grey aggregates.

SUDwell P.U.3776 (Non UV) does discolour under UV. This does not affect
its performance otherwise for outside use and many companies use it
because of its price advantage. SUDwell.co.uk P.U.3776 (Non UV) is suitable
for brown, yellow, green and darker coloured pebbles but not
recommended for blue, grey or lighter coloured aggregates. Care should
be taken not to use resin rich scrapings from the mixer or wheel
barrow. After a few mixes these should be discarded. Any pooling or
ponding of the resin may cause foaming which will result in an
unsightly finish. During the winter months white spirit or some sort
of solvent will need to be applied to the laying trowel periodically
to aid laying with the stonemix. This material cures very fast during
hot summer days and has approximately 10 mins trowelling /working time
during hot days.

Use between 1.8kg - 2kg per 25 kg of pebble (8%). The larger the
pebble the less binding resin you will need. For very small pebbles
1-3mm or smaller use 10% binding resin to aggregate.