Surfacing Wax

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Boat Suppliers

Surfacing Wax

SKU:SM-SWAX02

$4.55 USD

$4.55 USD ~~USD~~

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In stock

Size: 2oz

2oz Pint Quart Gallon 5 Gallon

Quantity

Key Specs

Mix Ratio: 1/2 oz per quart (2 oz/gal, 20 drops/oz) into the final coat only
Resin Type: Wax additive (sanding aid) for polyester resin & gelcoat
Catalyst$: Wax additive (sanding aid) for polyester resin & gelcoat

Surfacing wax turns unwaxed polyester resin or gelcoat into a coat you can sand. Left alone, the face of an unwaxed coat stays sticky where it meets air. Mix this into the last coat and a thin wax film rises to the top, shuts the air out, and the surface cures hard and dry to the touch, ready to sand and polish.

Final coat only

Leave it out of every laminating ply and every coat that something else still has to bond to. Wax on a surface stops the next layer from bonding, which is exactly why it belongs in the finish coat and nowhere else. Going back over a waxed coat means sanding it and wiping it with acetone first. It does not kick the resin on its own: the coat still needs its normal MEKP dose.

Sanding aid for unwaxed polyester resin and gelcoat
Dose 1/2 oz per quart, 2 oz per gallon
Final coat only; MEKP still required
Sizes: 2 oz bottle, pint, quart, gallon, 5 gallon pail

Need the volume of that last coat? Get it from the resin calculator, then dose by the quart.

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Technical Specifications

Mix 1/2 oz per quart (2 oz/gal, 20 drops/oz) into the final coat only

Resin TypeWax additive (sanding aid) for polyester resin & gelcoat

Mix Ratio1/2 oz per quart (2 oz/gal, 20 drops/oz) into the final coat only

CatalystMEKP still required - wax is an additive, not a catalyst

Apply OverFinal layer only; sand + acetone-wipe the wax film before any recoat

Best ForTack-free, sandable final coats on unwaxed resin/gelcoat

Do I need to add wax to gelcoat?

Only with unwaxed gelcoat. Air stops the surface of polyester from curing, so unwaxed gelcoat stays tacky until you stir surfacing wax into the final coat, about 1/2 oz per quart (2 oz per gallon), or spray PVA over it. Leave the build coats unwaxed so they recoat without sanding, and wax only the last coat.

What's the difference between waxed and unwaxed gelcoat?

Waxed gelcoat has an additive that rises to the surface as it cures, sealing out air so the coat hardens tack-free and is ready to sand. Unwaxed (sanding) gelcoat has no additive, so it stays tacky until you add surfacing wax to the final coat or cover it with PVA. Use unwaxed when you plan to lay more coats, and use waxed for the last coat.

Why is my gelcoat still tacky and not curing?

A tacky surface almost always means air-inhibited cure, not too little catalyst. Unwaxed gelcoat will not harden on top until you add surfacing wax to the final coat or seal it with PVA. Other causes are too little MEKP, temperatures below about 60°F, or high humidity. Confirm your catalyst ratio, warm the shop, and wax or PVA the last coat.