ABL (STEVENS) Resin & Glass
NOTES ON FISH PONDS & TANKS
SHEATHING IN GRP (Glassfibre Reinforced Plastic) of
Concrete Fish Ponds. The advantages of a GRP Sheathing over coating the
concrete with "G4" Polyurethane Varnish, for which four coats are
used is that concrete can crack in the winter frosts but the GRP will not crack
and has a glass smooth surface.
TOXICITY Under cured GRP will emanate Styrene (40%
content of most resins). With drinking water tanks this would not be toxic to
humans despite unpleasant taint but would be toxic to fish as they breathe
water. Our final surface coating resin (top coat or flowcoat) is a quality
Isophthalic Gel Coat to which wax has been added at time of manufacture so that
the user does not have to add the tack free solution which has been added to
all initial Gel Coats (which are wax-free) if they are to be used as Top Coat.
ERECTION OF TENT For Fish
Ponds in the open it is essential to erect a tent: a tarpaulin sheet stretched over
horizontal pole and pegged to the ground. Both ends of the tent must be left
open so that the Styrene fumes can freely escape. If emanation were restricted
hardening and cure would be inhibited. The tent must be longer than the pond to
avoid driving rain entering the open ends at an angle. The tent should be
erected 14 days before commencing work to allow the concrete to thoroughly dry.
PREPARATION OF THE CONCRETE All corners, vertical and
horizontal, must be rounded with sand and cement as leaks are apt to occur when
dovetailing glassfibre into internal 90 degree angles. The concrete should be
reasonably smooth but not billiard ball smooth as the initial barrier coat of
"G4" would not penetrate as well as it should. Do not use 'Unibond' as it contains ammonia. There must be no trace of
bitumen as this attacks polyester resin and inhibits hardening. Allow 14 days
for sand/cement to dry.
INITIAL BARRIER COAT OF "G4" POLYURETHANE
VARNISH The purpose of this is to act as
a barrier preventing alkali in the cement attacking the resin and the dampness
striking through the concrete inhibiting hardening and cure of the resin. The
"G4" is applied in one coat at 210g /sq.metre
(10.76 sq.ft). The "G4" hardens upon contact
with air, so tins should be promptly re-sealed each time "G4" is
decanted. It goes tacky-hard in one hour and continues to cure for 12 hours,
but when "G4" is used in this application the laminating resin must be applied
with a maximum of two hours or sooner after the "G4" has gone
tacky-hard. Delay will inhibit the degree of adhesion of resin to
"G4". The "G4" must be brush applied: NOT with spray gun as
inhalation of fumes must be avoided.
APPLICATION OF GRP SHEATHING The concrete must be strong,
especially the bottom where the weight of water bears. For ponds up to 5' depth
two laminations of medium thickness Chopped
The preferred roller is the aluminium Paddle Roller
6" x 1 1/2" o.d. which has a plastic handle
with a socket into which a broom handle will fit, which eases the work. Always
overlap pieces of CSM by 2". Do not lay edge to
edge. The final surface tissue cannot be rolled with metal roller which would
'pick it up'. It is applied with a brush stippling action. The CSM and tissue
are applied with laminating resin. As
soon as the tissue is hard then the final topcoat (flowcoat) is applied at
spread rate of
2 ½ oz. per sq.ft. This can be pigmented
with polyester colour paste added to the gel in ratio not exceeding 10% by
weight. Pigmented gels cure more positively than
non-pigmented as UV light inhibits cure of non-pigmented resins. The usual colour in fish-ponds is Super Black.
FINAL CURE Allow a minimum 14 days after work is
completed with tent still erected. Introduction of heat will expedite cure. After this flush out with hot water, steam or several changes of
water. Under cure is visible if a white sheen appears on the surface of
the laminate after water is introduced.
WORKING TEMPERATURE This should be not less than 16C = 60F
throughout the work. If work has to be interrupted it may be found that the
finished edge of laminate has curled up away from concrete due to 6% shrinkage
of resins as they harden and cure. Cut this out and overlap 3" onto extant
laminate with the subsequent laminate.
These notes are given in good faith for general
guidance purposes only and since actual operating conditions, methods and
application techniques are beyond our control, we cannot accept liability for
any losses however they may occur.
Unit 4,