Expert Epoxy Casting Tips - Part 2: Mastering Project Processing for Perfect Results

Have you also admired those massive hand-made epoxy river tables? Maybe something smaller, like a serving tray, knife holder, or lamp?

Honestly, I was sold since the first YouTube video I saw years ago. The epoxy casting process might need a bit of preparation and know-how, however, the results are amazing and definitely worth it. Let's go through it together and learn useful tricks to make it as easy as possible.

In the previous article, we went through the process from the preparation phase to the epoxy mixing and casting. You have waited a few days as the mold has hardened. Carefully released it from the form, but wonder what the next steps are?

Index Part 1 - Project Preparation

1. What is the size of your project?

2. What epoxy volume will you need?

3. Epoxy selection

4. Casting preparation

5. Making casting form/mold

6. Mixing

7. Casting

Index Part 2 - Project processing

1. Rough mold processing

2. Cut to size

3. Sanding

4. Repairs

5. Surface finish

Index Part 3 - Lessons learned

1. Mixing

2. Bubbles

3. Leaks

4. Bending

5. Shelf life

6. Tooling

1. Rough mold processing

After a mold is released from the form, there is a time for the first flattening step. That is usually done via routing or rough grinding. Depending on the project, you have the following options:

For smaller projects like epoxy inlays or crack filling where base wooden material stayed flat and relatively low epoxy volume was applied, these tools are to be used to remove excessive hardened resin:

• Belt or orbital hand-held power sander
  Higher sand paper grids (60-80grt) are to be used. Friction generates heat. Make sure not to grind small areas for too long otherwise, epoxy color and structural degradation will appear.
  The usage of sandpaper designed for epoxy is a game changer. With cheap materials work takes forever.
  Do not forget good working place ventilation and, if possible, appropriate dust extraction. Personally, even with dust exhaust, I still wear a protective face mask.

• Hand power plainer or stationery plainer/jointer
  It can be combined with grinding. Local overheating is not an issue. Just watch for epoxy chipping if the cutting blades are not sharp enough.

Larger projects with more epoxy surfaces e.g., serving trays or river tables are a little more demanding. Two basic options are available in this case:

• Flattening jig and hand router
  Most common among hobby craftsmen. The flattening device is generally a horizontal bed with two straight and leveled bars on its sides. Over them drives a trolley holding a hand router with a large flat bit. Jigs can be self-made to respect the needed project size or purchased from several companies.
  I use a robust router trolley in combination with the self-made working bed made out of standard aluminum profiles.

  

• CNC router
  The “professional” way is to use CNC for almost perfect surface flatness. You do not need to own one yourself. Just search for woodworking companies in your area and give them a call. Most of them are willing to provide such a service for a reasonable cost.

2. Cut to size

At this point, you have in your hands a perfectly flat mold. Yes, yet there are either scratches from high-grit grinding or swivel marks caused by routing. Those will be handled later. Now, your project is ready to be cut to the requested size.

Cutting can is usually done by:

• Table saw or track saw

• or CNC for more complex shapes

Use cutting blades with a higher tooth count to prevent edge chipping.

If you plan on having beveled or rounded edges on your project, now is the best time. Edges are mostly formed by hand routers. When the surface is finely sanded, routing is going to definitely cause additional new scratches, and the whole fine-grinding procedure has to be repeated.

To have fine, clean edges, use sharp, high-quality routing bits. To me, it also helped increase the router’s rpm. You acquired some scrap pieces a moment ago from the cut-to-size step. Try out edge routing on them first to ensure you have everything set right.

3. Sanding