Application guide

Resin for Water Tank Manufacturing

Water tank manufacturers need a resin that wets out glass reinforcement cleanly and cures into a strong, leak-resistant laminate for long-term structural integrity.

Consistent wall thickness, no weak spots.

FRP (fibreglass-reinforced plastic) water tanks are widely used across residential, commercial and industrial sites because they resist corrosion, weigh far less than concrete or steel equivalents, and can be fabricated in sectional panels or one-piece cylindrical shells to fit almost any site. None of that is possible without a resin system that wets out the glass reinforcement evenly and cures into a rigid, watertight laminate — which is exactly the role General Purpose (GP) polyester resin plays in tank fabrication.

What manufacturers build

Water tank manufacturers produce sectional panel tanks (bolted together on site from moulded FRP panels), one-piece cylindrical or rectangular tanks, underground and overhead storage tanks, and process tanks for industrial water storage. Capacities range from a few hundred litres for domestic use to hundreds of thousands of litres for institutional and industrial storage.

Why this material suits the work

GP Clear Resin is Samrat FRP Traders' general-purpose orthophthalic unsaturated polyester resin — the same broad category of resin used across the FRP tank industry. Its clear, low-viscosity liquid form wets out chopped strand mat and woven roving quickly during hand lay-up, so laminators can build up tank walls in multiple passes without the resin dragging or leaving dry patches. Because it cures into a hard, chemically resistant laminate once catalysed, it forms the structural shell that gives an FRP tank its strength and its resistance to the water it holds.

Required resin characteristics

Low viscosity for fast, even wet-out of glass reinforcement across large tank surfaces
A workable gel time that gives fabricators time to lay up multiple reinforcement layers before the resin sets
Good mechanical strength once cured, to withstand the hydrostatic pressure of a full tank
Reliable, room-temperature cure so tanks can be fabricated without special curing equipment
Consistent batch-to-batch quality, since tank walls are built up in several resin-and-reinforcement passes that all need to bond and cure alike

Process context

Tank panels or shells are typically built by hand lay-up: reinforcement (chopped strand mat, and often woven roving for added strength) is placed against the mould, and resin — catalysed with an MEKP hardener and a cobalt octoate accelerator — is worked into the reinforcement by roller or brush. Multiple layers are built up to reach the specified wall thickness, with each layer wetted out before the next is added. Once the full laminate has gelled and cured at room temperature, the panel or shell is released from the mould, trimmed, and — for sectional tanks — bolted together with the other panels on site to form the complete tank.

Advantages

Fast gel time (under 8 minutes) keeps production cycles efficient without sacrificing lay-up time
Non-accelerated cure system lets fabricators adjust MEKP and cobalt octoate dosage to suit workshop temperature and batch size
Working from a single documented grade across a tank run keeps the laminate consistent from panel to panel
Consistent 99% purity and controlled viscosity reduce the risk of dry patches or resin-rich areas that weaken a tank wall

Common products

Sectional panel water tanks
One-piece cylindrical and rectangular storage tanks
Underground and overhead water tanks
Industrial process water and raw-water storage tanks

Common questions

Is GP Clear Resin suitable for potable (drinking) water tanks?

GP Clear Resin is a general-purpose orthophthalic resin suited to the structural laminate of FRP tanks. For tanks intended to hold potable water, always confirm the complete tank construction — including any food-grade gelcoat or lining used on the water-contact surface — meets the relevant drinking-water standards for your project.

What reinforcement is used with GP Clear Resin for tank walls?

Tank walls are typically built up with chopped strand mat, often combined with woven roving for additional strength in larger tanks. Samrat FRP Traders supplies E-glass chopped strand mat reinforcement alongside its resin range.

How is GP Clear Resin catalysed for tank fabrication?

It is cured at room temperature with an MEKP catalyst and a cobalt octoate accelerator, the same non-accelerated system used across Samrat FRP Traders' general-purpose grades. Dosage is adjusted to suit workshop temperature and the gel time required for a given panel size.

Can GP Clear Resin be used for chemical storage tanks as well as water tanks?

GP Clear Resin is formulated for general-purpose FRP work, including standard water storage. For tanks holding aggressive chemicals or requiring higher corrosion resistance, a vinyl ester resin system is generally the more suitable choice.

What size tanks can be built with GP Clear Resin?

It is used across the size range typical of FRP tank fabrication, from small domestic sectional tanks through to large industrial storage tanks — wall thickness and reinforcement layers are adjusted by the fabricator to suit the required capacity and structural load.

Need resin for your water tank production?

Get a bulk quote or talk to our technical team about the right grade and dosage for your tank fabrication line.

Contact Samrat FRP Traders