Jesmonite® AC100 vs AC730 vs AC84: Which to Choose?

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Quick comparison at a glance

All three are water-based casting variants in the Jesmonite® family, and all three are eco-friendlier than plaster, concrete or epoxy. The differences come down to where you can use the finished piece, the look you are after, and how forgiving the material is for a beginner. Here is the short version.

Jesmonite® AC100

• Best for: indoor decorative casting such as trays, coasters, vases, candle holders and small homeware.
• Where it lives: indoor only.
• Skill level: easy to pour and very forgiving, the natural starting point.
• Variant: a gypsum base powder mixed with a liquid acrylic.
• Look: smooth, stone-like homeware finishes that take all Jesmonite® pigments beautifully.

Jesmonite® AC84

• Best for: versatile projects and smaller objects, indoors or out, in a smooth modern or a concrete-style look.
• Where it lives: indoor and outdoor (weather-resistant).
• Skill level: easy to pour, just like AC100.
• Variant: a cement-based variant, mixed at 1:5.
• Look: smooth straight from the mould, or a robust acid-etched concrete finish; takes all Jesmonite® pigments.

Jesmonite® AC730

• Best for: tough stone and textured effects, including pieces that go outside.
• Where it lives: indoor and outdoor (weather-resistant).
• Skill level: expert level; a tough, cement-based composite.
• Variant: a cement-based variant, mixed at 1:5, coloured with pre-mixed colours.
• Look: natural stone and heavier textured finishes, smooth or acid-etched.

AC100: indoor decorative casting

Jesmonite® AC100 is the go-to for indoor decorative work, and it is where most makers start. It is a two-part, water-based variant: a gypsum base powder plus a liquid acrylic, so you can work with it comfortably at a kitchen table.

The standard mix is 1 part Jesmonite® liquid to 2.5 parts base powder by weight, so always follow the exact ratio printed on your product or instructions, as this is what gives you a reliable set. Pieces demould in around 30 minutes and are fully cured after 24 hours. That short demould time is a big part of why beginners love it: you see a result fast and can move straight on to the next pour.

AC100 gives a smooth finish and pairs perfectly with silicone coaster and tray moulds and with pigments, where a small amount of powder goes a long way. If you want a decorative piece that stays indoors, AC100 is almost always the right answer.

AC84: the versatile all-rounder, indoor and outdoor

Jesmonite® AC84 is the most versatile of the three, and the newest addition to the range. It is a cement-based variant mixed at 1 part Jesmonite® liquid to 5 parts base, and it is weather-resistant, so it works both indoors and outdoors. Best of all, it is easy to pour, as beginner-friendly as AC100, but with the freedom to make pieces for the garden or bathroom too. AC84 demoulds after around 2 hours and is fully cured after 24 hours.

AC84 takes all Jesmonite® pigments, so your colour options are wide open. You also get a choice of finish: leave it smooth straight from the mould for a sleek, modern look, or give it an acid-etched finish for a robust, concrete-style appearance. Both cement-based variants, AC84 and AC730, can be etched with acid or, more gently, with ordinary household vinegar, a friendlier way to get the same effect at home. That combination of ease, durability and finish options makes it a great next step once you have a pour or two of AC100 behind you. AC84 is also a great choice for smaller objects.

AC730: stone effects, indoor and outdoor

Jesmonite® AC730 is a tough, rugged, cement-based variant, mixed at 1 part Jesmonite® liquid to 5 parts base. That cement base is what unlocks convincing stone and textured looks, and, crucially, it is suitable both indoors and outdoors. If you want to cast something for a garden, a porch or a windowsill that catches the weather, AC730 is built for it.

AC730 is the expert-level variant of the three, so treat it as a step up once you are confident with casting. It is coloured with pre-mixed colours rather than loose pigments, and can be left smooth or given an acid-etched concrete finish. It demoulds after around 4 hours and is fully cured after 24 hours. Once cured, an outdoor piece benefits from the right protection: a penetrating sealer gives AC730 invisible water resistance without changing the look, and a Flexiguard sealer is the other option for AC730.

Choose AC730 when the finish and the location both point to stone: heavier, textured, natural-looking pieces that need to survive outside.

Indoor vs outdoor: what matters

The single biggest deciding factor is often where the finished piece will live. Get this right and the choice narrows quickly.

• Indoor only: AC100. It is the specialist for homeware and decorative objects that stay inside.
• Indoor and outdoor: AC730 and AC84. Both are weather-resistant, so pick between them on look and skill level, not location.
• Easy and versatile, indoors or out: AC84.
• Tough stone and texture: AC730.

For anything heading outside, plan for sealing as part of the job rather than an afterthought. A penetrating or Flexiguard sealer suits the cement-based AC730 and AC84, while an acrylic satin or gloss sealer is designed for AC100 pieces that stay indoors. Matching the sealer to the material is as important as matching the material to the project.

Which Jesmonite® for your project

Here is a simple way to decide.

• Making indoor homeware and just getting started? Go with AC100. It is forgiving and fast to demould.
• Want a versatile, weather-resistant material that is still easy to pour? Choose AC84, indoors or out, with a smooth or concrete finish.
• After a tough, natural stone finish for outdoors and happy to work at expert level? Reach for AC730.
• Just getting started and want everything in one box? An AC100 starter kit is the easiest way in (starter kits are available for AC100 only).

If you are new to all of this, do not overthink it. Our Jesmonite® starter kits are all based on AC100, the ideal variant to learn on, and give you the material plus the essentials to make your first piece. We do not offer starter kits for AC730 or AC84, so for those you simply buy the Jesmonite® base and Jesmonite® liquid separately once you are ready. Once you know how casting feels, choosing between AC100, AC730 and AC84 becomes second nature.

Ready to start casting? Browse the full Jesmonite® range to compare AC100, AC730 and AC84 in one place, or grab an AC100 starter kit and make your first pour this week.