Valspar Composites
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Mold Repair:

Re-Spraying the Gel Coat

Page 3 of 4
 

The following are recommended procedures for re-spraying:

1. The objective is to re-spray and sand thoroughly, leaving no shiny spots.

2. Sand the area with 220 grit sandpaper using a block or an orbital sander. Do not sand with your fingers. This will cause distortion in the surface creating dips or groves.

3. Sand the area twice the size of the area to be re-sprayed.

4. Clean the surface using a solvent and a clean rag. All contaminates left on the surface will affect the adhesion of gel coat.

5. Tape off the area to be worked-on where possible on a sharp break or contour adjacent to the area - even if this means expanding the area slightly in size. This minimizes any slight color or texture differences after spraying.

6. Areas that may possibly be exposed to overspray should be covered. Mark the adjoining area to indicate where the actual spray spot is. This will make it easier to keep track of where you should concentrate your millage.

7. Use gel coat from the same batch the part was sprayed with.

8. Catalyze the gel coat with 2% catalyst by weight. Gel coat can be thinned with Styrene. Do not use more than 5% Styrene or your cure may be inhibited.

9. Stir the mixture thoroughly. It is advisable to use a metal putty knife for stirring the gel coat mixture. A wood stirrer will absorb the catalyst and affect the catalyst percent.

10. Use a siphon spray gun. Test the gun on a panel to adjust the spray pattern. The smaller the area to be sprayed, the more the air pattern and fluid flow should be closed. Air pressure should be at approximately 20 - 40 lbs.

11. Position the lighting so you can see the spray pattern as it forms on the surface.

12. Spray the patch area uniformly. Avoid producing runs. Move in horizontal and vertical passes while spraying. Allow proper flow to minimize orange peel. Produce a sufficient build up of gel coat for sanding and buffing. Lower the millage output toward the ends of the sanded area to form a feathering effect. Do not spray outside the sanded area.

13. Clean your equipment immediately after the spraying. Flush with clean solvent. Fill the container with solvent, spraying the solvent through the gun. Back flush the siphon tube by blocking the nozzle of the gun to force solvents in and out of the tube.

14. Allow the gel coat to cure overnight.

 

 






 
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The information and recommendations found in this web site
are intended for FRP Professionals. Results of repair or maintenance are dependent on
many variables. No warranties of any kind are expressed or implied.