Using Gelcoat Brushing (White, Black & Neutral)

Brushing gel coat is a basic for hand laminating fabricating and will remain tacky between coats allowing re-coating if required.  Use for repair work and interior coating.  Isophthalic grade is the upper grade of resins which means the product is waterproof and is suitable to use below the water line. It has limited chemical resistance but is suitable for mild acids.  For best practice, it’s best to test the chemical for any adverse effects. 

Other applications include water tanks, potable water tanks, waste tanks, grey water tanks. Brushing sands very well and blends in with existing gelcoat surfaces.

How to Use:

Surface Preparation: 

Surface should be clean, dry, and free from oil, grease, dirt, wax or other contaminants. If required, repair structural damage, laminate or fiberglass. Gelcoat application is normally the final repair step. Remove defective Gelcoat or surface finish by sanding with 80/120 grit. Prepare surface 1/2"=1" beyond the damaged area at either side. For pinhole repair, just open the pinhole and sand lightly.


For approximately 1 tablespoon of Gelcoat, add 6 to 8 drops of Liquid Hardener or for 4 tablespoons of Gelcoat, add 1/4 teaspoon of Liquid Hardener. Mix thoroughly. Working life of the mix is approximately 10 to 12 minutes.


If you’re tinting this product it only contains white with no other color added, so it’s considered pure white so keep in mind that you can't make a solid color from white as it will always be a pastel shade. Use 1 to 4 tablespoons in a mixing cup and add Rayplex Color Paste to tint to desired color. 


Use Rayplex Pigments only.  They are made specifically for gelcoats and should be used when tinting or coloring polyester gelcoat. Any chemical foreign to the polyester can interrupt the curing process and damage properties.  No more than 1 ounce of color agent should be added to a quart of white gel coat.

For part fabrication: 

This white brushing gel coat can be brushed onto a mold with good coverage usually with one coat.  The gel coat covers well, but sharp corners may require and extra coat for proper coverage.

For interior coverage: 

Add 5% of Rayplex wax solution.   Wax solution floats to the surface and prevents oxidation which gives gel that sticky feel when cured.  This will give a tack free  non sticky surface.  If more gel coat must be applied, the surface will need to be well sanded and the wax coating removed with solvents.


Fill damaged area slightly above existing surface. Apply pressingly with plastic spreader or putty knife. Avoid air entrapment. Sand smooth when hard with medium grit sandpaper (80/120 grit). Wet sand with fine grit (220/400/600/1200...etc.). Buff with a polishing compound to achieve the desired gloss. Clean tools with acetone.


1)  Don't over catalyze as this will prevent the gel coat form curing properly. Gelcoat is still tacky (a finger leaves a fingerprint) after hardener has been mixed into the resin and proper cure time has elapsed.  Never exceed 2% catalyst by volume or below .5%.  We recommend not using this product below 60F.   See the Catalyst mixing guide in the Tech Tips section of  Always mix in clean containers, used coffee cups can impart a yellow cast to gel coat. 

2)  It is recommended that gel time be checked in the customer's plant because age, temperature, humidity and catalyst will produce varied gel times.

 3)  Never thin with or add  acetone as this will inhibit the gel coat from curing properly and will be soft.  Use streyne to thin with.


Prior to full cure, gel coat can be removed with acetone. Be sure to put all tools into an acetone bath before the gel coat has time to harden.


 Information present herein has been compiled from sources considered to be dependable and is accurate and reliable to the best of our knowledge and belief but is not guaranteed to be so. Nothing herein is to be construed as recommending any practice or any product violation of any patent or in violation of any law or regulation. It is the user’s responsibility to determine for himself the suitability of any material for a specific purpose and to adopt such safety precautions as may be necessary. We make no warranty as to the results to be obtained in using any material and, since conditions of use are not under our control, we must necessarily disclaim all liability with respect to the use of any material supplied by us. Rayplex Ltd

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Disclaimer: The information contained herein and provided by RAYPLEX LTD is considered accurate.
However, no warranty is expressed or implied regarding the accuracy of the data, the results to be obtained
by the use thereof, or that any such use will not infringe any patent. Before using, user shall determine
the suitability of the product for the intended use and user assumes all risk and liability whatsoever
in connection therewith.




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