GlassRoxx: What It Is and How to Use It in Jesmonite® Casts

Because it starts life as recycled glass, GlassRoxx gives your work texture and a subtle catch of light that flat colour alone cannot. The granulate is small and even, which means it spreads well and blends into most casting materials without clumping. And since the colour comes from water-based pigments rather than solvents, it fits neatly alongside the water-based Jesmonite® variants many makers already use.

You can find it on the GlassRoxx product page, and it sits within our wider range of casting additives alongside other effect materials.

The look GlassRoxx creates

GlassRoxx adds depth. Where a plain cast reads as a single solid tone, glass granulate scatters tiny points of reflection through the surface, giving the piece a hand-made, mineral quality. Think of the speckle you see in stone or terrazzo, but with a gentle glassy shimmer instead of a matte finish.

How strong that effect looks depends on how you use it. A light sprinkle on the surface reads as a delicate dusting of sparkle. A heavier, mixed-in dose gives a denser, all-through speckle that shows on every side of the object, including the parts you sand back. Both are valid; it simply comes down to the style you are after.

GlassRoxx suits small homeware beautifully: coasters, trays, dishes, candle holders and jewellery all benefit from that extra bit of interest. Because the granulate is fine, it also works well in pieces with crisp edges and shallow detail, where a coarser filler might get lost.

How to use GlassRoxx in your casts

GlassRoxx doesn’t come with a manual: you simply mix it into your Jesmonite® or Reslin® mix. There are two main ways to use it, and you can combine them once you are comfortable.

Surface-sprinkle technique

The sprinkle method keeps the glass on show at the front face of your piece, which is the side that sat against the bottom of the mould.

1. Prepare your mould as normal and have your GlassRoxx to hand before you mix.
2. Sprinkle a thin, even layer of GlassRoxx into the base of the mould first. This is where your finished, visible surface will form.
3. Mix your casting material and pour it gently on top of the granulate so you do not disturb the layer too much.
4. Tap the mould lightly to release air bubbles, then leave it to cure fully before demoulding.

This approach uses less material and concentrates the effect exactly where the eye lands. It is a great way to try GlassRoxx for the first time.

Mixed-in technique

Mixing GlassRoxx straight into your casting material spreads the sparkle throughout the whole piece, so it shows on every face and stays visible even after sanding.

1. Mix your casting material to the correct ratio first.
2. Add a small amount of GlassRoxx and stir it through evenly. Start conservatively; you can always add more on your next pour.
3. Pour into the mould, tap out the bubbles, and cure as usual.

Add the granulate gradually and keep notes on how much you used, so you can repeat a result you like. A little glass goes a long way, and too much can affect how the material flows into fine detail.

One thing to keep in mind: with Jesmonite® you sand the cured piece back to bring the glass to the surface, just like terrazzo. With Reslin® there is no need to sand, the glass shows through as the piece cures.

You don’t have to cast with it at all, either: GlassRoxx also looks lovely simply scattered loose in a bowl or dish as decoration.

Combining GlassRoxx with pigments and Jesmonite®

GlassRoxx really comes into its own when paired with Jesmonite® AC100, the water-based variant most makers reach for when casting indoor homeware such as trays, coasters and candle holders. AC100 is beginner-friendly, mixes to a smooth consistency and demoulds after about 30 minutes, which makes it forgiving while you experiment with how much glass to add.

Because AC100 is water-based and non-toxic, it pairs naturally with the water-based pigments already in GlassRoxx. You can also colour the AC100 itself with pigments to build a solid base colour, then let the recycled glass add contrast and shimmer on top. A tinted base with a complementary GlassRoxx speckle usually reads far richer than either element on its own. See our guide to colouring Jesmonite® for pigment techniques.

A few pointers when combining them:

• Decide your base colour first, then choose a GlassRoxx tone that either blends softly or deliberately contrasts.
• Keep the glass dose modest at first. You can judge the effect once a test piece has cured, since colours often look different wet versus dry.
• Follow the exact mix ratio on your AC100 instructions. AC100 is mixed 1:2.5 (Jesmonite® liquid to base by weight), and adding fillers does not change the fact that this ratio needs to stay correct for a strong cast.

If you want a bolder, stonier speckle rather than a glassy one, reach for StoneRoxx instead. StoneRoxx is made from granite that adds texture, depth and character. True terrazzo is made from small Jesmonite® chips you make yourself, but StoneRoxx is a handy ready-made alternative that gives a similar terrazzo-like speckle. Many makers keep both on the shelf: GlassRoxx for shimmer, StoneRoxx for that crushed-stone look.

Why it is a sustainable choice

Decorative sparkle has a reputation for being wasteful, largely because so much of it is single-use plastic glitter or microplastic. GlassRoxx takes a different route. It is made entirely from recycled glass, giving material that would otherwise be waste a second life as a decorative effect. The colour comes from water-based pigments rather than solvent-based ones.

That fits the wider philosophy behind our casting range, which leans towards eco-friendlier materials such as water-based Jesmonite® and plant-based Reslin®. Choosing a recycled additive is a small decision, but it lets you add character to your work without adding plastic to the world. For makers who care where their materials come from, that peace of mind is part of the appeal.

Get started with GlassRoxx

GlassRoxx is one of the easiest ways to lift a plain cast into something with real depth and a sustainable story behind it. Whether you sprinkle it onto the surface for a delicate shimmer or mix it through for an all-over speckle, it pairs beautifully with beginner-friendly Jesmonite®. Browse the GlassRoxx product page to pick your colours, and explore the full range of casting additives to find the perfect finish for your next project.