A buyer sent us a rendering in September: a 42 mm medal, a deep cobalt field, a raised silver falcon in the center, and a background that glowed like stained glass. The note said “transparent enamel, please.” We could build it — but not at the line width in the drawing, and not without deciding first what metal sat under the paint. That is the conversation this page is about, and it follows the same order as our custom medal production flow — artwork first, then the fill spec, then the plating underneath it.
Transparent enamel is the one finish in our shop where the artwork and the process argue with each other. Opaque color forgives almost everything. A thin film still hides the metal. A slightly wobbly fill still reads as the right red. A budget plating still disappears under pigment. Take away the pigment’s hiding power and every one of those tolerances collapses at once, because what the customer sees through the film is the plating, the polish, the tape line, and the cure — not the color on the spec sheet.
This guide sits inside the wider work of custom medals: the material, plating, fill, and assembly decisions that decide whether a design is buildable at all. We cast, plate, fill, and pack in Huizhou — the sales office is in Dongguan — and we have been running this line since 2010 under Badge Artisans. What follows is what we tell buyers on the phone when they ask for a transparent field, including the two things almost nobody puts in writing: the 0.5 mm minimum fill width, and the high-temperature tape that goes on the back of the medal before a single drop of paint goes in.
Here is the route: what “transparent” actually means in this trade, why 0.5 mm is a floor rather than a preference, the taping step, the two-stage drying curve and how it fails, how the plating underneath rewrites the color, how transparent compares with the other three fills, which designs we turn down, and how a transparent job moves through our line from artwork to carton.
Three Words Buyers Use for One Finish — and Why the Difference Costs Money
Search results blur “translucent enamel medals,” “transparent enamel medals,” and “glass enamel medal” into a single product. In our workshop they are one material family with three different promises, and the promise you pick changes the quote.
Transparent means you see through the film to the metal. The color you perceive is the paint multiplied by the substrate. A cobalt blue over bright silver is a sapphire; the same cobalt over bright gold turns teal; over antique bronze it goes muddy violet. Nothing about the paint changed. The metal did.
Translucent means light passes but scatters, so the film looks milky rather than clear. In practice we get there by thinning the film or by adding an opacifier, and it is the least stable of the three looks — a translucent film is the one that shows every variation in film thickness, because scattering amplifies thickness differences instead of hiding them. If a client asks for “frosted,” we usually steer them to a matte texture in the mold plus a solid color, which is repeatable batch to batch.
Glossy is a surface property and has nothing to do with transparency. A solid glass enamel fill can be mirror-glossy and completely opaque. Buyers conflate the two constantly, then wonder why their “transparent” sample came back looking like ordinary enamel. It was ordinary enamel — glossy, opaque, correct, and not what they meant.
One more distinction worth having in your pocket. If a supplier offers genuine kiln-fired vitreous enamel on a zinc medal, ask how the medal survives a firing cycle several hundred degrees hotter than zinc’s 385°C melting point. It does not. What the awards trade calls glass enamel is a cold-cure resin system that is filled, cured, and polished — which is exactly why it can sit on a die-cast zinc body at all.
Why 0.5 mm Is a Floor, Not a Preference
Our mold shop can cut a line 0.3 mm wide. Our casting floor holds a 2 mm minimum wall on an 88-ton machine all day. So when we say a transparent field cannot be narrower than 0.5 mm, the limit is not the metal and not the mold. The limit is the paint.
Three things happen below half a millimeter.
The film loses its color. Transparent pigment has no hiding power by definition. Perceived color intensity depends on how much light travels through the film before it hits the substrate and comes back. At 0.3 mm the path is short, the plating’s yellow or gray dominates the return, and the fill reads as a wash rather than a color. Customers describe this as “chalky” or “faded.” It is not faded. It is thin.
Surface tension pulls the film off the walls. Enamel shrinks as solvent leaves. In a narrow channel, that shrinkage draws material toward the center of the floor, thinning the film where it meets the metal edge. The result is a pale halo tracing every letter and every contour — the single most common complaint on transparent samples. At 0.5 mm the channel is wide enough that the cured film stays flat across the floor and the edge stays saturated.
Polishing cuts through. Glass enamel and imitation hard enamel are lapped flush with the metal after curing. A transparent film has less sacrificial thickness to give, so a heavy polish pass at the edge can open a bright line of plating straight through the color. We run a lighter polish on transparent fields and check them under raking light, not straight on.
This is also why “just make the soft enamel thinner” is not an answer. Soft enamel holds a 0.3 mm line comfortably because it is opaque: pigment particles scatter the light before it ever reaches the metal, so a thin film still reads as solid color, and the recessed profile is part of the look. The 0.2 mm difference between soft enamel’s floor and everyone else’s is not a rounding error. It is the entire reason a transparent design has to be redrawn.
| Fill type | Minimum fill width | Back tape required | What the film does |
|---|---|---|---|
| Soft enamel (recessed, opaque) | 0.3 mm | No | Opaque pigment sits in the channel below the metal lines |
| Imitation hard enamel (opaque, polished flush) | 0.5 mm | No | Opaque, flat, level with the metal after lapping |
| Solid glass enamel (opaque, polished flush) | 0.5 mm | No | Opaque, high gloss, deepest solid look |
| Transparent glass enamel | 0.5 mm | Yes — high-temperature tape on the reverse | Shows the plating through the film; depth comes from film build, not from pigment |
The Step Nobody Puts in a Process Video: Taping the Back
Any medal with an opening through it — a pierced silhouette, a cut-out star, a slot, the hole that takes the ribbon ring — cannot hold liquid enamel. It runs out the back. Even a shallow recess on a thin casting can wick paint through a pinhole in the die casting that nobody noticed until fill day.
So before a transparent job goes to the fill bench, we tape the back.
The tape has to survive both cure stages without shrinking, curling at the edge, or leaving adhesive in the cavity. Ordinary masking tape fails at the first stage: it lifts at the corner, paint siphons under it, and you get a drip on the reverse that has to be ground off — and grinding the back of a thin medal is how you chip the front. We use a high-temperature tape rated well above the 100°C full-cure pass, pressed down along the full perimeter of every opening, with the seam burnished so there is no tunnel for paint to travel along.
The sequence on the bench: clean the cavity, apply tape, fill the first color, half cure, fill the second color, half cure, full cure, then strip the tape. The tape stays on through both oven stages, because a film that is still soft will sag into the opening the moment the support is removed. It comes off only after the 100°C pass, when the film is hard enough to hold its own edge.
Without tape, three failures show up in order. First a crater on the front face, where paint drained away down the hole. Then a stalactite on the back, which has to be removed by hand. Then a thin, pale ring around the opening, because the film at the edge drained to nothing. All three are scrap, and all three are preventable with a strip of tape that costs less than the phone call.
One consequence buyers should know about: taping gives the enamel a flat, slightly matte back face inside the opening. Most clients never see it, because the reverse of a medal faces the wearer. But if your design is meant to be read from both sides — a pierced medal held up to the light — tell us at quoting. The tape line becomes part of the design, and on some jobs we would rather change the fill plan than leave a visible flat plug.
Taping is also manual, one medal at a time, and it is a real labor line in the quote. It does not scale with the casting machine. That is one reason a transparent job is priced by tier and by design rather than by a per-unit number pulled off a chart.
The Drying Curve We Actually Run — and the Three Ways It Fails
Enamel is not fired. It is cured, in two stages, and the curve is not a suggestion.
Stage one: 60–70°C for 60–90 minutes. This is a half cure. Solvent leaves slowly, the film gels, and the surface stays slightly open so the next color can bond to it instead of sitting on a skin. Rushing this stage is the root cause of most transparent defects, because transparent film shows you the inside of the paint.
Stage two: 100°C for 60 minutes. This is the full cure: hardness, adhesion, chemical resistance, and the final gloss. It also happens to be the same temperature the plating line’s tunnel oven runs at, 100°C for 40 minutes after the coloring bath — so by the time a medal reaches the enamel bench it has already seen that heat once and is dimensionally settled.
Why not one step at 100°C? Because the solvent has to leave before the film hardens around it. Skip the ramp and you get bubbles, pinholes, and a surface that looks boiled. In an opaque color you might get away with it. In a transparent film you are looking straight down at the crater.
Why not cooler and longer? An under-cured film stays soft, picks up dust and packing marks, and deforms when medals are stacked in a bag. Transparent shows stacking marks far worse than opaque, because the mark changes the film thickness and therefore the color.
| Failure | What you see | Root cause | What we change |
|---|---|---|---|
| Bubbles and pinholes | Small craters, visible through the color | Solvent flashing off in a single-stage cure | Longer half cure, slower ramp to 100°C |
| Sagging at the rim | Color pools thick at the edge, thin in the middle | Pass laid too heavy in one go | Two thinner passes instead of one thick one |
| Mottling and color shift | Patchy, uneven tone across a field | Plating variation showing through, or uneven film | Opaque base coat, or matte mold texture |
| Crater at an opening | Hollow ring around a hole or cut-out | No tape, or tape lifted at the corner | Re-tape with burnished seam, refill |
| Milky haze | Film looks cloudy rather than clear | Moisture in the air line, or under-cure | Dryer check on the compressor, re-cure |
The last one is worth a note for anyone specifying transparent work in a humid climate. Compressed air carries moisture, moisture lands in the film, and a transparent film has nowhere to hide it. We check the line dryers on the same schedule as the ovens.
The Metal Underneath Is Half the Color
This is the part of transparent enamel that surprises buyers most, and the reason we refuse to approve a transparent color on a sample plated differently from production.
A single transparent cobalt, filled to the same depth, on the same 40 mm casting, reads five different ways depending on what the plating shop put underneath it. Our plating line runs nine steps — alkaline copper for 500 seconds, acid copper for 20 to 60 minutes depending on the deposit, then the coloring bath, then the tunnel oven at 100°C for 40 minutes — and the coloring step is where the substrate color is set.
| Plating under the film | Same cobalt transparent fill reads as | Why |
|---|---|---|
| Bright gold | Teal, green-leaning, warm | Yellow substrate subtracts blue from the return light |
| Bright silver / nickel | Clean sapphire, the coolest and most “true” | Neutral substrate returns the color unchanged |
| Antique bronze or copper | Muddy violet-brown, blue nearly lost | Warm brown substrate plus a darker surface kills saturation |
| Black nickel / gunmetal | Deep navy, highest apparent saturation | Dark substrate absorbs the stray light and deepens the tone |
| Bright gold, red transparent | Orange-red, almost coral | Same subtraction, opposite direction on the spectrum |
The practical rules that come out of that table:
Pick the plating before you approve the color. Never sign off a transparent Pantone on a silver sample if the production run is gold. The two will not match, and no amount of re-filling will fix it. This is the same logic that governs the rest of the finish decision, which we break down in our medal plating finishes comparison.
If the color must be exact, we put a base coat under it. An opaque white or light-tint fill goes in first, gets a half cure at 60–70°C, and then the transparent color goes on top of that. Now the substrate is neutral and the transparent film reads the same on gold, silver, or bronze. It costs a second fill pass and a second cure cycle, and it is the only way to hold a brand color in a transparent film.
Texture is a tool, not just a look. A matte surface cut into the mold steel by spark erosion — EDM, followed by heat treatment of the die — diffuses the reflection under the film. On a large transparent field, that diffusion is what stops the color from looking patchy, because it removes the mirror that was showing every variation in film thickness. It costs mold time. On big flat transparent areas it is usually the difference between a pass and a redo.
Dark platings buy saturation, bright platings buy brightness. If a client wants a jewel-like deep color, black nickel under the film does more for it than a heavier paint pass ever will.
Transparent Against the Other Three Fills
Buyers usually arrive with a shortlist of two: transparent, or the thing they saw on a competitor’s medal. Here is the honest comparison, from a shop that runs all four fills on the same floor.
| Transparent glass enamel | Solid glass enamel | Imitation hard enamel | Soft enamel | |
|---|---|---|---|---|
| Surface profile | Flush with metal, high gloss | Flush with metal, high gloss | Flush with metal, satin to gloss | Recessed below the metal lines |
| Minimum fill width | 0.5 mm | 0.5 mm | 0.5 mm | 0.3 mm |
| Back tape | Required on any opening | Not required | Not required | Not required |
| Where the color comes from | Paint multiplied by the plating | Pigment only | Pigment only | Pigment only |
| Cure passes | Two or more, plus base coat if color must match | Two | Two | Two |
| Best use | Jewel-depth fields, premium awards, brand palettes that can flex | Deep saturated color, premium look, exact Pantone | Premium look at a lower tier than glass | Tight budgets, bright spot color, strong 3D relief |
| Weak point | Color moves with the plating; narrow lines fail | Flat, less depth than transparent | Less depth than glass, softer edge | Paint sits low, wears at the rim |
| Cost tier | Quoted by design and tier | Quoted by design and tier | Quoted by design and tier | Quoted by design and tier |
The short version: soft enamel is the workhorse and the cheapest route to a bright, readable medal with strong relief. Imitation hard enamel is the premium look most sports and corporate programs land on. Solid glass enamel is for buyers who want depth but need the color to be the same on every unit. Transparent is for the job where the metal is part of the design — a silver falcon behind a cobalt sky, a gold sun behind an amber field. If you are still choosing between the two opaque routes, our soft enamel vs hard enamel guide goes deeper, and the enamel medals page covers the full fill menu.
Designs We Turn Down — and What We Offer Instead
We would rather lose a week at the artwork stage than lose a production run. These are the requests that come back marked up.
| Design element | Can we do it? | Why | What we suggest |
|---|---|---|---|
| 0.3 mm hairline in a transparent color | No | Film too thin to hold color or survive polish | Keep the hairline in opaque enamel, or widen to 0.5 mm |
| Large flat transparent field, one color | Risky | Pooling and film variation read as patches | EDM matte texture in the mold, or break the field with metal lines |
| Gradient from one color to another | No | Enamel is filled channel by channel; there is no blend | UV print, which also holds a 3D step up to 7 mm |
| Photographic portrait or halftone | No | No dot structure in a poured film | UV print or engraving |
| Two transparent colors blended in one channel | No | Hard boundary only | Separate channels with a metal divider |
| Transparent fill across a pierced opening | Yes, with tape | The opening has no floor until we tape it | Accept a flat back face inside the opening |
| Narrow deep slot under 1 mm wide | Usually no | Air trapped at the bottom becomes a bubble | Widen the slot, or split it into two shallower channels |
Two of these are worth expanding, because they come up weekly.
Hairlines. Designers love a 0.25 mm rule, and in a vector file it looks crisp. In transparent enamel it is a pale scratch. If the line carries meaning — a date, a thin border — put it in an opaque color and let the transparent live in the wide fields. That hybrid is common on premium medals and it reads better than an all-transparent face.
Gradients. A poured film cannot blend. Anyone who shows you a transparent enamel sample with a smooth gradient is showing you a UV print, a printed insert, or a photo of something else. UV printing handles gradients, photographs, and fine halftone, and it can follow a 3D step up to 7 mm, which is why it wins on complex art. The trade-off is a printed surface rather than a glass depth — our UV printed vs enamel medals comparison lays out where each one stops.
Sending a Transparent Job Through Our Line
Artwork arrives, and within 24 hours we send back a drawing plus a build note. On a transparent job that note is where the project is actually won: we mark every channel under 0.5 mm, flag every opening that will need tape, and ask which plating the color will sit on. Most of the redesign happens in that first exchange, before anyone has quoted a tier.
Sampling runs 7 to 10 days. Approve the sample on the real plating, in the real lighting, and if the color has to be exact, approve it with the base coat in place. Bulk production runs 7 to 15 days after sample approval, with a 100-piece minimum per design and a 30,000-plus piece daily output across the floor.
Scale is worth putting in perspective. A 40 mm medal at 3 mm thick is roughly 3.77 cm³ of zinc alloy — π × 2² × 0.3 — which at 6.7 g/cm³ comes to about 25 grams before plating and enamel. A 5,000-piece order is therefore around 126 kg of finished metal, and on casting capacity alone it is about a sixth of one day’s output, roughly four hours of machine time. But transparent work does not finish on the casting floor. Taping is manual, the base coat is a second pass, and the cure stages are fixed at 90 minutes plus 60. On a transparent job the enamel bench sets the delivery date, not the die casting machine. That is why we quote 7 to 15 days rather than promising the number the machine could theoretically hit.
Quality control runs in three stages — incoming material, in-process on the fill bench, and final inspection before packing — with a 100% pass standard on the delivered lot. The plant holds BSCI, Disney, ISO9001, Reach, RoHS, TUV, Sedex, and USJ certifications, and we ship to more than 50 countries.
On cost, the honest answer is that a transparent fill is quoted by design and by quantity tier, and we will not put a unit number on a page like this because the variables — channel width, number of colors, taping, base coat, plating — move it more than volume does. What we can say is the direction: plating is our most expensive finishing route, ahead of spray painting and electrophoresis, and transparent enamel adds manual steps on top of whatever the plating already costs.
If you have a design with a transparent field, send the vector file and tell us which plating you are considering. We will come back within 24 hours with a marked-up drawing showing exactly which channels survive as transparent, which need widening, and which should stay opaque — and a tiered quote for the version that will actually run.
The Six Questions That Come Up on Every Transparent Quote
Can you fill transparent enamel into any design?
No. The floor is 0.5 mm of channel width, and the fill has to sit over a plating that supports the color you want. Designs with hairlines under 0.5 mm, gradients, halftones, or very large unbroken flat fields need to be redrawn or moved to a different process before they can be quoted as transparent.
Why can’t you just use a 0.3 mm line like soft enamel does?
Because soft enamel is opaque. Its pigment scatters light before it reaches the metal, so a thin film still reads as solid color. Transparent film has no hiding power, so at 0.3 mm the plating dominates the return light and surface tension pulls the film off the channel walls, leaving a pale halo around every edge. The metal and the mold are not the limit here — the paint is.
Will transparent enamel yellow or fade over time?
A correctly cured film at 100°C for 60 minutes is stable, and the transparent pigments we run hold their tone. The failures we see are process failures rather than age: an under-cured film stays soft and picks up marks, and an over-cured film yellows. Both are visible in transparent work long before they would show in an opaque color, which is why the cure curve matters more here.
Can you match a specific Pantone in a transparent fill?
Only if we control the substrate. On bare plating, the same paint reads differently over gold, silver, and antique bronze, so an exact match is not meaningful until the plating is fixed. For a brand color that has to hold, we fill an opaque white or light base coat first, half cure it, then apply the transparent color on top. That neutralizes the plating and makes the Pantone repeatable.
Does transparent enamel cost more than solid enamel?
It is quoted by design and quantity tier rather than by a fixed unit price, because the cost drivers are different: taping is manual, a base coat adds a fill pass and a cure cycle, and narrow channels slow the bench down. The plating underneath is usually the larger line item either way.
What if my design needs a gradient or a photo behind the transparent color?
Then it is not an enamel job. Enamel is poured channel by channel, so there is no blend and no dot structure. UV printing handles gradients, photographs, and fine detail, and it can follow a 3D step up to 7 mm. Many premium programs use both: UV print for the illustrated area, transparent enamel for the border and the wide color fields.
Related product page: medals with a rotating centre — our spinning medal range: a moving inner disc on a die-cast body, 100-piece minimum.
