Epoxy Tumblers Explained

An epoxy tumbler is a stainless steel drinking cup that has been decorated by hand with glitter, paint or vinyl and then coated in clear two-part epoxy resin, which is rotated on a motorized cup turner while it cures so that it dries into a smooth, glassy, hard shell. The glitter or design sits under the clear coating, so it looks deep and shiny and does not rub off the way loose glitter would. That is the whole idea, and it explains both why the cups look the way they do and why they cost more than a printed tumbler: each one is made by hand, in layers, with hours of cure time. This guide covers how they are made, what "food safe" claims mean and what they do not, cure times, glitter, care, and how an epoxy tumbler differs from a sublimation one.

What an epoxy tumbler is

The base is an ordinary insulated stainless steel tumbler, typically a 20 ounce size in the maker's tutorials. The maker builds the design on the outside surface: paint, a glitter layer, vinyl lettering or an ombre of several colors. The clear epoxy goes over everything, then the cup is kept turning until the resin has set. Because the resin is a thick liquid until it hardens, the cup has to rotate slowly and stay level or the epoxy sags and pools.

The finish has a recognizable look: a thick, high-gloss, slightly rounded surface with the glitter suspended beneath it. Sublimation tumblers, by contrast, have a flat printed design that is part of the coating, with no thickness you can feel. The two products are made differently and behave differently, as the comparison section below explains.

How an epoxy tumbler is made

Makers vary in the details, but the sequence is consistent. The steps below follow a published beginner tutorial from Silhouette School, which describes making a glitter tumbler with epoxy on a 20 ounce stainless steel cup.

1. Prepare the surface. The maker protects the top and bottom of the cup with painter's tape and stuffs the inside with paper towels so paint does not get in. In that tutorial the cup is spray painted first in a color matching the glitter.
2. Apply the base for the glitter. The tutorial brushes Mod Podge onto the cup with silicone brushes, then pours glitter on in sections while turning the cup by hand on a spinner. It recommends glitter that is colored all the way through rather than only on its surface, so the shine holds up when the surface is sanded.
3. Seal it. The tutorial applies two coats of Krylon Clear Coat spray before any epoxy goes on.
4. Mix the epoxy. The tutorial uses Amazing Clear Cast, a two-part epoxy, with 10 milliliters per layer, made of 5 milliliters of part A and 5 milliliters of part B. It mixes slowly to avoid bubbles.
5. Apply and turn. The epoxy is applied to the cup, which goes on a cup turner. The tutorial uses a WRMK Spin It and says the cup should turn "pretty slowly" and stay completely horizontal.
6. Wait. The tutorial gives a spinning time of 6 to 8 hours per coat.
7. Sand and recoat. The tutorial sands with 180 to 220 grit sandpaper after the first epoxy coat, applies another coat, and does not sand after the final coat.

A second Silhouette School post reviews an epoxy drying machine for tumblers and notes that "if you make epoxy tumblers you know they take a long time due to all of the drying time." That is the practical reality. A tumbler with two coats of epoxy occupies the turner for much of a day or longer, which is part of why makers batch their work.

These are one maker's published method, using particular products. Other makers use other epoxies, different layer counts, different torch or heat steps for bubbles and different cup turners. If you are buying rather than making, the point is that a good epoxy tumbler is a multi-day, multi-layer job, and a very low price for a very elaborate cup is worth a question.

How epoxy hardens

Two-part epoxy is made of a resin and a hardener that must be mixed together. The hardener molecules react with the resin and link it into a three-dimensional polymer network, which is why the cured material is hard and does not melt back into a liquid. This is a chemical reaction rather than drying, which matters for three reasons.

• The ratio matters. The resin and hardener have to be measured accurately. Wikipedia's article on epoxy notes that resin and hardener ratios are usually between 3 to 1 and 10 to 1 by weight, depending on the product. Some products, including ArtResin, are mixed in equal parts by volume. Whichever the product, the instructions on the label govern, and a wrong ratio can leave the resin soft or tacky.
• The reaction gives off heat. Wikipedia notes that curing is exothermic. In a thin coat on a cup that is not much of an issue, but it is the reason large pours behave differently from thin coats.
• Temperature and thickness affect the result. ArtResin's FAQ recommends a workspace between 75 and 85 degrees Fahrenheit and building in thin layers of about one eighth of an inch.

Cure times: working time, touch dry, fully cured

Epoxy has three timelines, and mixing them up is a common mistake.

Those figures are ArtResin's, for ArtResin, at the temperatures it recommends. Other epoxies differ, and the Silhouette School tutorial's 6 to 8 hours of spinning per coat is a different measure again, the time the cup is kept turning so the coat levels out and gels. The point for a buyer is that a tumbler that has been spun and has a hard surface is not necessarily fully cured. A careful maker allows additional time before the cup is used or shipped, and the product's label should say how long.

Glitter

Glitter is the signature of this kind of tumbler. Modern glitter is typically made of small, flat, precisely cut particles, usually combining aluminum and a plastic film (PET) with reflective coatings. Craft glitter and cosmetic glitter are different products sold for different uses.

Two practical points follow.

• Colored-through glitter holds up. The tutorial's advice about glitter that is colored through rather than only on its surface exists because the surface gets sanded between coats, and surface-only color can wear away.
• Glitter is a microplastic concern. Wikipedia notes that plastic glitter is a microplastic problem, and that the European Union banned plastic-sourced glitters as of October 2023. In a sealed epoxy tumbler the glitter is locked under resin, which is one of the advantages of the format, but loose glitter during crafting, sanding dust and disposal are where the environmental issue arises.

"Food safe" and what it does and does not mean

This is the part of the subject that deserves the most care. Epoxy resin makers often describe their products as food safe, and the claim usually refers to the US regulation on resinous and polymeric coatings, Title 21 of the Code of Federal Regulations, section 175.300.

What the regulation says, based on the published text:

• It governs "resinous and polymeric coatings" used as food-contact surfaces, and it applies to coatings applied as continuous films or enamels over metal, or intended for repeated food-contact use on a suitable surface, acting as a barrier between the food and the surface.
• It lists the permitted basic polymers, including epoxy resins made from specific starting materials, and permitted catalysts and cross-linking agents.
• It sets limits on how much material may be extracted from the cured coating by food-simulating liquids, with different numerical limits for single-use and repeated-use containers.
• It allows these epoxy resins "except as coatings in packaging for powdered and liquid infant formula."

What follows from that, and what does not:

• A statement that a resin "complies with 21 CFR 175.300" is a manufacturer's claim about the composition and testing of the product. It is not the same as a government agency having tested or approved the finished tumbler.
• The regulation is about the cured coating. ArtResin's FAQ makes the same point in its own words: its resin is safe for food contact "when properly measured, mixed per directions, and fully cured," and it says the product has passed independent testing for leaching and migration. Both conditions, accurate measuring and full cure, are things the maker controls, and a buyer cannot see them.
• The regulation does not mention tumblers, glitter, vinyl or paint, and a finished tumbler is a stack of materials. The resin may be compliant while the glitter, adhesive and paint under it are not food-contact materials at all. In the usual design those layers are on the outside of the cup and the resin is a barrier over them.
• In the tutorial described above, the epoxy goes on the outside of the cup. Whether the resin can touch a drink depends on the individual cup, which is a fair question to put to the maker.

So "food safe epoxy" is a reasonable thing for a maker to say about a resin and a reason to ask follow-up questions, not a certification of a finished cup. A responsible seller will tell you which resin they used, whether the resin touches the inside of the cup, how long it cured, and whether the cup is meant for drinking from or for display.

Safety when making them

Making epoxy tumblers involves uncured resin, and the risks sit with the maker rather than the buyer.

• Skin sensitization. Wikipedia's article on epoxy explains that exposure to epoxy resins can, over time, induce an allergic reaction, and that dermatitis commonly appears on the hands and forearms. People who work with uncured resin regularly are the ones at risk, which is the reason for gloves and for avoiding skin contact.
• Ventilation and measuring. The manufacturer's safety instructions govern, and they are worth reading before starting.
• Sanding dust. Sanding between coats raises dust, and sanding cured epoxy and glitter calls for ordinary dust precautions.

For a buyer, the relevant point is simpler: once the epoxy is fully cured, the uncured-resin hazards no longer apply. Fully cured is the operative phrase.

Care

The same tutorial states plainly that glitter tumblers with vinyl are not dishwasher safe and must be washed by hand. The maker's care card, if there is one, is the better guide for any particular cup, and hand washing is the safe default. The tutorial gives no further care specifications, so treat anything beyond that, such as avoiding drops and extreme heat, as common sense rather than published guidance.

Epoxy versus sublimation

Both produce a decorated cup. They are different crafts.

Our guide "Sublimation Tumblers: How They're Made" covers the sublimation side, including the typical heat and time settings sellers publish, which run from about 350 to 400 degrees Fahrenheit. Epoxy and sublimation are not rivals so much as different looks, and some makers do both.

What to ask a seller

Because an epoxy tumbler is handmade, the useful questions are about the process.

1. Which epoxy was used, and is it described by the maker as suitable for food contact?
2. Is any resin on the inside of the cup, or only the outside?
3. How many coats of epoxy, and how long did the cup cure before shipping?
4. What is under the epoxy: glitter, paint, vinyl, and are they sealed?
5. Is it hand-wash only?
6. Is the cup meant for drinking, or for display?

A clear, specific answer to each is a good sign.

Seeing a tumbler on camera

Glitter and depth are hard to judge in a single photograph, because the whole point of the finish is how it catches light. In a live sale you can watch the cup turned in the light, see the surface up close and ask the seller your questions before you bid.

On ShopBidz, Girlssippin, a seller from Cottage Grove, Minnesota, sells tumblers. Kraftys, from Stroudsburg, Pennsylvania, is also a seller on ShopBidz. Both can be watched live, and the questions in the list above are the right ones to ask any seller of handmade drinkware.

Bottom line

An epoxy tumbler is a stainless steel cup decorated with glitter, paint or vinyl and sealed under clear two-part epoxy that is hand-applied and turned on a cup turner while it cures. In one published method, each coat spins for 6 to 8 hours, the cup is sanded lightly after the first coat but not the last, and the care instruction is to wash by hand. Epoxy cures by a chemical reaction, so the mix ratio and full cure matter; one manufacturer lists 24 hours to touch dry and 72 hours to full cure. "Food safe" claims usually point to the FDA regulation on resinous and polymeric coatings, 21 CFR 175.300, and they are a manufacturer's statement about a resin, not an approval of a finished cup. Ask which resin was used, whether the resin touches the inside of the cup, and how long it cured. Epoxy gives a deep, glossy, handmade look, while sublimation gives a flat, printed one.