A small set of resin coasters is a satisfying way to learn epoxy. You get several chances to practice the same pour, try a simple color combination and make something you can actually use. The key is to plan the thickness and curing time before you start mixing.
To make epoxy resin coasters, choose a suitable silicone mold, calculate the amount of mixed resin, measure both components accurately, mix thoroughly, pour and let the pieces cure as directed. Demolding is only part of the process: the resin needs its full recommended cure before it is ready for drinks or gift wrapping.
This beginner project uses shallow, flat coasters with clear resin and an optional single-color accent. Keep the first set simple so you can learn how your resin and mold behave.
What you need for a first set
- A clean, dry silicone coaster mold with a smooth interior
- Epoxy resin appropriate for the planned casting depth
- Clearly marked measuring cups, a mixing container and mixing sticks
- Nitrile gloves, eye protection and any other protection specified for your product
- A level work surface with a protective covering
- A resin-compatible colorant, if desired
- A clean cover to keep dust off the curing pieces
- Optional cork backing or small protective feet for the finished coasters
Work with the ventilation required by the resin’s safety instructions. Set everything out before opening the bottles, and keep children and pets away from the work area.
1. Match the resin to the mold’s depth
Measure the inside of the mold and decide how thick the coaster will be. A deep cavity does not have to be filled to the rim. For an easy first set, a simple round or square shape makes it easier to estimate material and check that the finished surface is flat.
Our Art & Craft epoxy resin is intended for small castings, including coasters. The USA product range specifies pours up to approximately 3/4 inch at a time. That is a product limit, not a target thickness for every coaster; check the instructions supplied with your kit and the conditions for your particular pour.
Inspect the mold under a light. Scratches and debris can transfer to the resin, and a matte cavity can produce a matte face. Browse our resin molds for suitable shapes, then check the cavity dimensions before planning a batch.
2. Calculate the mixed resin before measuring the parts
For a plain round cavity, use the cylinder formula: volume = 3.1416 × radius × radius × depth. The radius is half the diameter. Use the same unit for every dimension.
Here is a practical example for four round coasters, each 4 inches across and 1/4 inch thick:
- One coaster: 3.1416 × 2 × 2 × 0.25 = approximately 3.14 cubic inches.
- Convert to milliliters: 3.14 × 16.387 = approximately 51.5 mL.
- Four coasters: approximately 206 mL, or 7 US fluid ounces, of mixed epoxy.
- Allowing about 10% for material left in cups gives roughly 227 mL; rounding to 230 mL is a convenient planning amount.
This is an example for straight-sided, flat cavities. Decorative rims, tapering and raised details change the volume. The allowance is a planning choice, not part of the mixing ratio. Our epoxy volume calculator can help with project estimates.
The total above includes resin and hardener together. It does not mean 230 mL of each part, and it is not permission to exceed the product’s batch-size limits.
3. Measure and mix accurately
Magic Resin Art & Craft uses 1:1 Part A to Part B by volume, or 100:90 by weight. For the 230 mL example, measure 115 mL of Part A and 115 mL of Part B. If weighing instead, 100 g of Part A requires 90 g of Part B. These are different measuring methods; a volume estimate cannot be treated as the same number of grams.
Mix for about 4–5 minutes as directed, scraping the sides while stirring. Work thoroughly rather than whipping the mixture. Prepare the molds first so you can pour promptly after mixing, and do not scrape the remaining residue out of the cup onto the project.
Never add extra hardener to speed up curing. If you use a different resin formula, follow that product’s ratio rather than carrying this one over.
4. Keep the first color design simple
A clear coaster is a useful practice piece. For a subtle accent, divide a little of the fully mixed epoxy into a separate cup and add a small amount of compatible colorant within its recommended loading. Leave the main portion clear.
Pour the clear portion into the mold, then add a small stream of tinted resin near one side. A gentle pass with a mixing stick can soften the boundary. The colors may continue moving before the epoxy sets, so treat the first coaster as a sample rather than expecting identical patterns across the set.
Our epoxy pigments and colorants offer different effects. Mica gives shimmer, while a suitable transparent dye can preserve more of the see-through appearance. Follow the colorant’s instructions; adding more is not always the way to get a better result.
5. Pour on a level surface and protect the cure
Keep the molds supported on the level work surface throughout the pour. Pour gently into each cavity, staying within the chosen depth. Inspect the surface under a light for trapped air and dust.
Use only bubble-removal methods compatible with both the resin and the mold. Avoid a direct flame on silicone and prolonged heating. Repeatedly heating a small pour can create more problems than it solves.
Place the dust cover above the molds without touching the resin. Leave the pieces undisturbed under the product’s recommended conditions. If you are making gifts, schedule the pour early enough to allow the full cure and any finishing steps before wrapping.
6. Demold carefully, then finish the edges
Follow the demolding guidance for the resin you used. Peel the silicone away gently while supporting the coaster. If the casting is still too soft to hold its shape, give it more time under the recommended conditions instead of forcing it out.
Once the resin is ready for finishing, check for a sharp lip around the edge. Smooth only what needs attention, using suitable dust control and the protection specified for sanding cured epoxy. Sanding a glossy face will dull it, so avoid sanding the whole surface just to correct one edge.
After the required cure, add compatible cork backing or evenly placed protective feet if desired. Check the coaster on a flat surface: it should sit securely without rocking, and its top should support a glass evenly.
Before you put the coasters to use
Do not judge readiness for a hot mug by whether the resin feels dry. Follow the full-cure and heat-use guidance for your exact product. Treat coasters as drink supports, not trivets for cookware, and do not use a finished piece that remains sticky.
Wipe away spills with a soft cloth and avoid abrasive cleaning. If you are giving the set away, include the care advice supplied with your resin and explain when the pieces are ready to use.
For the next batch, note the mold dimensions, mixed quantity, colorant and room conditions. That short record makes it much easier to repeat a result you like. If you need help selecting the resin or resolving a soft casting, contact the Magic Resin team with the product name, ratio, pour thickness, temperature and photos of the project.
