West Systems Epoxy
The Gougeon Brothers realized epoxy is an excellent moisture barrier coating, however, it was a difficult product to use and decided to address that. Founded in 1969, West Systems engineered their own proprietary epoxy that could easily be applied to fiberglass or wood boat surfaces. Their distribution is now worldwide and they are renowned for high strength 105 Resin Epoxy, particularly unique as it has variable cure times, depending on the hardener used.
Having built their own in-house team of chemists, West System has continued to tweak their formula to constantly give you the best moisture barrier coating available. Relentless testing on hardness, tensile strength, impact resistance, heat deflection, and moisture exclusion West System epoxy is constantly being modified and tested to provide your vessel with the most protection available.
West System’s two-part epoxies are developed for use in both boat building as well as repair. West System epoxy is formulated to not only provide strong physical properties but also ease of application. Users can use a variety of Fillers and additives which allow for further modifications so the epoxy can be tailored to your exact specifications, whether they be for construction, repair, maintenance, or other uses required.
The Basics of Mixing and Applying West System Epoxy
Mixing
Thoroughly measuring and mixing the 105 Resin Epoxy and Hardener of choice is crucial for epoxy to properly cure. Epoxy should be mixed in a clean plastic, metal, or wax-free paper container. Glass and foam containers should not be used due to danger from heat build-up. The ratio is to combine 5 parts Epoxy with 1 part Hardener. DO NOT attempt to change the cure time by altering the mix ratio as this can affect the product from properly curing.
There are two ways you can mix epoxy:
Dispensing with Mini Pumps
The west system Mini Pump is a convenient way to accurately mix your Epoxy and Hardener every time. They are calibrated so they deliver the correct working ratio every time. One full pump of resin for each full pump stroke of hardener gives you a working ratio. After pumping a stroke, allow the head to fully come back to the top before the next stroke. Partial Strokes will result in the wrong ratio.
Dispensing by Weight or volume
Another way to mix epoxy and hardeners is by weight or volume. 105 Resin Epoxy, 205 Fast Hardener, and 206 Slow Hardener when measured by weight/volume should be mixed in a 5 parts resin to 1 part hardener ratio. 105 Resin,207 Special Clear Hardener, and 209 Extra Slow Hardener, when measured by volume, should be mixed in a 3 parts resin to 1 part hardener or when by weight 3.5 parts resin to 1 part hardener. It is recommended to use a mixing stick with a beveled edge to thoroughly mix the epoxy and get the corners of the mixing containers.
Working with Additives or Fillers
Epoxy fillers are used to thicken epoxy/hardener mixtures for specific applications. They are generally categorized as either adhesive, for bonding, or fairing for sanding and fairing applications. They can be used to control consistency, bridge gaps, create fillets, or alter the cured density of epoxy. The Thickness of a mixture is controlled by the amount of filler added. There is no strict formula or measuring involved besides you judging the consistency of what will work best for what you need.
Filler should be added in a two step process:
- Mix the Desired quantity of epoxy/hardener thoroughly before adding fillers. Begin with a small batch and allow room for the filler.
- Blend in small amounts of filler until the desired consistency is reached.
For maximum strength, add only enough filler to completely bridge gaps between surface gaps without sagging or running out of the gap. When used for joins a small amount should squeeze out when clamped. Do not fill a mixing cup more than 1/3 full of epoxy before adding filler to make a thicker mixture. Stir 407 Low density Filler or 410 Microlight Filler as smoothly as you can blend it when making fairing compounds. To make an easy to sand epoxy the thicker the mixture the better.
Surface Preparation
Surface preparation is important to ensure the epoxy can securely bond to a surface and cure. There are three main steps to properly prepare a surface for work.
Clean - Surfaces should be free of any contaminants such as wax, mold, oil, or grease. Surfaces can be cleaned with lacquer thinner, acetone, or other appropriate solvents. Before the solvent dries wipe the surface with paper towels. It is recommended to clean surfaces before sanding to avoid sanding the contaminant.
Dry - For proper adhesion, the surface should be as dry as possible. If necessary you can use a hairdryer, heat lamp, or hot air gun to accelerate the drying process. Watch for condensation when working outdoors and use fans to move air in confined spaces.
Sand - Sand smooth non-porous surfaces to provide a texture for the epoxy to bond to. 80 grit aluminum oxide sandpaper will provide good texture. After sanding remove all dust.
Special Preparation for various materials before applying epoxy:
Teak/Oily Woods - Wipe with acetone 15 minutes before coating with epoxy. Solvents remove the oil and allow the epoxy to penetrate the surface.
Steel, Lead - Remove contamination by sanding or grinding to a bright metal. Coat with epoxy then sand fresh epoxy into surface. Re-coat or bond after first epoxy coat gels.
Aluminum - West sand with 80 grit before applying epoxy.
Plastics - Adhesion with epoxy varies with plastics. Hard rigid plastics such as ABS, PVC, and Stryene have better adhesion with good surface preparation. After sanding or flame oxidizing it is a good idea to conduct an adhesion test.
Polyester - Clean contamination with silicone and wax remover then sand with 80 grit paper to a dull finish.
Porous Woods - No special preparation is needed. If surfaces is burnished or dulled you can sand with 80 grit paper.
Hardwoods - Sand with 80 grit paper before applying epoxy.
Barrier Coating:
- Prepare the surface for epoxy bonding
- Mix as much epoxy resin/hardener as you can apply in working time. Once thoroughly mixed pour into a roller pan.
- Using a roller load a moderate amount of epoxy and roll the excess out.
- Roll the epoxy lightly and randomly over a 2 x 2 ft. are to evenly spread the epoxy.
- Increase the pressure as the roller dries out to spread a thin even film of epoxy. The Thinner the film the easier it is to avoid runs or sags and keep each coat even.
- Finish with light, even, long strokes to reduce marks from the roller. Overlap previously coated areas to blend areas together.
- With each batch of epoxy coat as many small working areas as you can. If a batch begins to thicken before applied you should discard it and mix a fresh batch.
- Drag a foam roller brush lightly over the fresh epoxy in long, overlapping, even strokes after each batch is applied.
Final Surface Prep
Using proper finishing techniques will add beauty to your efforts. The most common finishes used over epoxy are paint or varnish. These coatings provide protection from UV light.
Before any finishing work can be done the surface should be clean, dry and sanded.
- Allow the epoxy coat to cure thoroughly
- Wash the surface with a Scotch-brite pad and water and then dry with paper towels
- Using an 80-grit paper sand any runs or sags in the epoxy and sand to a smooth finish. If using a filling or high-build primer a 80-100 grit is recommended, 120-180 for primers and high solids coatings, 220-400 for high-gloss finish in most paints and varnishes.
- After sanded and you are satisfied with the texture, rinse with water and ensure the water does not bead. If the water does bead up it could be a sign of contamination. Wipe the area with solvent and dry with a paper towel. West sand again until the beading issue is gone.
After the epoxied surface has thoroughly dried you may proceed to your final coating. It is recommended to begin coating within 24 hours of the final sanding to reduce the possibility of contamination.
Clean Up
For large epoxy spills use sand, clay, or other absorbent material. Use a scraper to contain small spills and collect as much as possible. Follow up with absorbent towels.
- Do NOT use sawdust or other fine cellulose materials to absorb epoxy hardeners
- Do NOT dispose of epoxy hardener in trash containing sawdust or other fine cellulose materials
- Do NOT dispose of epoxy resin or hardener in a liquid state. They should be cured in small quantities to a non-hazardous inert solid.
To clean up uncured epoxy use a scraper to get as much up as possible. Clean the residue left behind with alcohol, acetone, or lacquer thinner.