How to Add Additional Layers of Fiberglass Resin

resin dripping from a stir stick
  • 3-6 hours
  • Beginner
  • 0-200
What You'll Need
Resin and hardener
Glass matting
Sandpaper(120 grit or 300 grit or material that will be painted)
Fiberglass roller or a 1/2" dowel rod for smoothing and rolling out
Acetone or denatured alcohol
Lint-free cloth for cleaning
Synthetic paintbrushes
Mixing containers
Latex gloves and protective glasses
Scissors for cutting glass mat

When laying fiberglass, multiple layers of fiberglass resin are often necessary. For best results, follow these instructions for adding additional layers of fiberglass resin.

General Fiberglass Tips

Sandpaper product to be fiberglassed down to its original surface before fiberglassing.

Clean with alcohol or acetone to remove oils that may make it difficult for the resin to stick.

For one square foot, use about 1 cup of prepared fiberglass resin.

Fiberglass in temperatures between 60 and 85 degrees F. Too cold and fiberglass won't harden; too warm and it will harden too quickly.

Protect your skin and eyes, by wearing gloves, eye protection and clothes to cover the skin.

Work in a well-ventilated area. If you aren't working outside, wearing a mask would be beneficial.

Allow to Cure after First Layer

After adding the first layer of resin, glass mat and resin, roll over the surface with a dowel rod to remove air bubbles. For best results, allow the first layer of resin and mat to cure for 2 to 4 hours before adding the next layer. The surface should be hard, but sticky.

mixing resin

Use a Fresh Batch of Resin

Apply freshly mixed resin for the second coat. Any leftover resin from the first layer will have hardened too much to use again.

Resin, Mat, Resin

Spread resin first, before adding the glass mat, and after, making a sandwich with the resin as the bread and the mat ais the meat. Spread resin very slowly to ensure more control and eliminate messiness. After spreading on a layer of the resin, press on the glass mat, pressing down gently with your fingers. Spread on more resin and roll out any air bubbles with a roller or dowel rod.

Repeat Layering

Repeat this process as long as necessary, but only if you are able to keep adding layers while the surface is still sticky. Finish with a glass mat. cleaned and primed before painting after it has hardened completely.

If you have to leave your project for 24 hours or more, you should sand and clean it with denatured alcohol and water before adding subsequent layers. After sanding, wipe down with a lint-free cloth soaked in alcohol until any sanding debris is removed. Then use a cloth soaked in distilled water. Allow it to dry completely before beginning to fiberglass again. Any leftover resin can be stored in the freezer to keep it from curing so that it can be used again. When it's time to fiberglass, take out the frozen resin early to allow it thaw. Use as soon as possible after thawing.

Prepare Finished Product

After hardening completely. clean thoroughly with a cloth and distilled water. Prime before painting for the most professional look.