Choosing between Jesmonite AC100 and AC730 sounds simple until you start making real products. Pick the wrong one, and the result can be frustrating: a smooth indoor formula used where moisture is a problem, or a cement-based mix chosen for a piece that really needed finer detail and easier casting. For crafters, workshop hosts, interior stylists, and small makers in Singapore, the difference matters because it affects finish, working time, durability, storage, and even what kinds of products you can sell with confidence. 

The short version is this: AC100 is the better choice for smooth, detailed, interior décor and beginner-friendly casting, while AC730 is the better choice for stone-like finishes, wet areas, and outdoor or more demanding decorative applications. Jesmonite itself describes AC100 as an acrylic modified gypsum composite designed to replicate very fine detail, while AC730 is an acrylic modified cementitious composite formulated to replicate concrete and stone surfaces. 

The short answer

If your priority is ease of use, clean detail, bright pigment work, terrazzo effects, marbling, and indoor homeware, AC100 is usually the right material. Jesmonite positions AC100 as its most popular material for creatives and beginners, and describes it as especially suited to decorative cast objects, mould replication, and interior applications. 

If your priority is outdoor durability, water exposure, a raw stone look, architectural-style pieces, or decorative objects that need to cope better with weathering, AC730 is the smarter choice. Jesmonite describes AC730 as a rapid-setting cement-based composite designed for external use, decorative architectural mouldings, small castings, and even water features. 

How the materials are actually different

The base chemistry changes the look and feel

The biggest difference is not just the name on the bucket. AC100 is an acrylic modified gypsum composite, while AC730 is an acrylic modified cementitious composite. In practical terms, that is why AC100 is associated with finer surface detail and a smoother decorative look, while AC730 is associated with concrete- and stone-like finishes. Jesmonite’s own FAQ makes this distinction very directly. 

AC100 is especially good when you want clean mould detail, a refined matte surface, and more freedom to play with pigments, terrazzo chips, and marbling effects. Jesmonite says AC100 is highly customisable, versatile, and widely used for homewares, internal décor, furniture, interior wall panels, and sculptural pieces. 

AC730 behaves more like a decorative micro-cement or concrete alternative. Its formulation includes fine decorative aggregate and powder pigments, and Jesmonite says the final surface can be brought out further through acid etching or finishing treatment. That is why AC730 tends to appeal to makers who want an earthy, architectural, or stone-inspired finish rather than a polished casting-resin look. 

The working time and mixing style are different

AC100 uses a 2.5:1 base-to-liquid ratio by weight and has a listed initial set of 15 to 20 minutes at 18°C. AC730 uses a 5:1 ratio and has a longer initial set of 30 to 45 minutes at 18°C. So while AC100 is often easier for fast decorative casting, AC730 gives more working time for laminating, reinforced pieces, and controlled decorative finishing. 

That does not mean the AC730 is “easier.” It is simply different. Jesmonite’s AC730 user guide makes clear that the product is primarily formulated for glass-fibre-reinforced laminating, with alternate ratios for chopped strand premix and gel-coat applications. AC100, by contrast, is framed more naturally around general casting, moulding, colour work, and broad decorative use. 

For people making small decorative objects at home, this distinction is important. AC100 generally feels more forgiving for quick pours, mould experiments, and workshop-style projects. AC730 is still usable for small castings, but Jesmonite repeatedly positions it as a material that really comes into its own when you want thin yet stronger sections, reinforced panels, or more architectural-looking results. 

The durability gap is where the decision becomes obvious

This is the section that usually decides the purchase. Jesmonite’s current AC100 technical data sheet says the material is suitable for internal use only, although it adds that if it is used externally, a sealer or suitable paint system is recommended to protect surface appearance. An older AC100 user guide is slightly more permissive and says it is suitable for internal and external use if protected, but the broader direction is still clear: AC100 is the interior-leaning option. 

AC730 is much more straightforward. Jesmonite says it is formulated for external use, is durable in all conditions of external weathering, has low permeability, reduced free lime for lower efflorescence compared with ordinary Portland cement systems, and is suitable for water features, statuary, garden ornaments, and external decorative work. Its technical sheet also includes weathering, porosity, and freeze-thaw performance data that reinforce that positioning. 

Even the finished story follows that same logic. Jesmonite’s own materials guide says AC100 is the gypsum product for indoor use and a smooth finish, while AC730 is the concrete alternative for more stone-like results and outdoor creations. That single contrast sums up most buying decisions. 

When AC100 is the better choice

Choose AC100 if your project is mainly about detail, surface control, and indoor styling. In real-world terms, that usually means pieces like these:

• Coasters, trays, candle holders, jewellery dishes, decorative bowls, and display pieces where a smooth finish and strong colour expression matter more than outdoor durability. Jesmonite positions AC100 for decorative cast objects and interior applications, and its Singapore distributor markets it as an easy, adaptable material for decorative moulded objects. 

• Terrazzo, marbling, and pigment-led projects where you want more visual freedom. Jesmonite’s AC100 guidance specifically supports pigment use and creative surface effects, and the brand describes AC100 as highly customisable and “the ultimate chameleon material.” 

• Beginner projects and workshops because AC100 is described by Jesmonite as its most popular product for creatives and beginners, and the smaller local pack sizes in Singapore make it less intimidating to start with. Concrete Everything currently lists AC100 sets in 3.5 kg, 17.5 kg, and 35 kg formats. 

• Fine-detail mould replication where crisp pattern transfer matters. Jesmonite’s FAQ states that AC100 is designed to replicate very fine surface detail, and thixotrope can be added to AC100 to create a gel-coat consistency for brushing onto mould faces without slumping. 

A good rule of thumb is this: if the piece will live on a shelf, coffee table, console, bedside table, or styling tray, AC100 is usually the cleaner and easier answer. 

When AC730 is the smarter choice

Choose AC730 if the piece needs to look and behave more like stone, concrete, or architectural décor. That usually includes projects like these:

• Planters, soap dishes, bathroom accessories, and outdoor décor where moisture or weather exposure is part of normal use. Jesmonite specifically says AC730 is the better choice for creations that come into regular contact with water, and its technical guidance supports use in external weathering and water features. 

• Garden ornaments, exterior decorative objects, and architectural-style pieces because AC730 is designed for external use and can be reinforced with AR glass for lightweight, higher-impact panels and mouldings. 

• Projects where you want a stone effect rather than a smooth décor finish. Jesmonite says AC730 contains decorative aggregates and is designed to replicate concrete and stone surfaces, with finishing options such as acid etching to bring out that surface character. 

• Makers who want lower efflorescence risk than ordinary cement-based looks. Jesmonite says AC730 has reduced free-lime content and lower alkalinity, helping reduce efflorescence versus ordinary Portland cement systems. 

One useful subtlety: AC730 can still look smooth when demoulded, but its real visual advantage shows up when you sand, etch, or otherwise finish it to reveal a more natural stone-like character. That is why it often feels more premium for bathware, planters, and architectural décor than AC100, even when both are beautifully made. 

What Singapore makers should consider

Warm conditions can shorten your real working time

Jesmonite’s published set times are given at 18°C, and the brand also notes that warmer environments make the material set faster. That is especially relevant in Singapore, where government sources describe the climate as hot and humid and regularly forecast daytime temperatures in the low- to mid-30s °C range. In other words, your actual working window may be shorter than the data sheet suggests, especially if you are mixing in a non-air-conditioned studio. 

For Singapore makers, that usually means three practical habits make a big difference: prepare moulds before mixing, mix smaller batches, and keep the right retarder on hand. Jesmonite sells separate retarders for AC100/AC300 and for cement-based systems such as AC730, and it explicitly says temperature and humidity can affect set times. 

Local pack sizes make AC100 easier to start with

From a purchasing standpoint, AC100 is the easier on-ramp in Singapore. Concrete Everything currently lists AC100 sets in 3.5 kg, 17.5 kg, and 35 kg sizes, while AC730 is listed in 6 kg and 35 kg sizes. That smaller AC100 entry pack is useful if you are experimenting, testing moulds, or learning the basics before committing to larger production runs. 

There is also a practical shelf-life angle. On Concrete Everything’s current product pages, AC100 liquid is listed for use within 12 months and the base within 9 months, while AC730 liquid is listed for 12 months and the powder for 6 months. For hobbyists or small-batch makers, that can make AC100 the lower-risk purchase because it is easier to buy small, test often, and waste less. 

If you already know you are making outdoor pieces, wet-area décor or stone-finish products, AC730 still makes sense despite the steeper starting point. But if you are building your first coaster line, running beginner workshops, or prototyping decorative homeware, AC100 is usually the smarter first material for the Singapore market. 

FAQs

Is AC100 or AC730 better for beginners?

AC100. Jesmonite describes AC100 as its most popular material for creatives and beginners, and it is widely used for indoor decorative casting. 

Which one is better for outdoor use?

AC730. Jesmonite formulates AC730 for external use and says it is durable in external weathering and suitable for water features. 

Which one gives a smoother finish?

AC100 usually does. Jesmonite says AC100 is designed to replicate very fine detail, while AC730 is designed to replicate concrete and stone surfaces. 

Can both materials be used for candle holders?

Yes, but sealers are a separate issue. Jesmonite says both AC100 and AC730 are suitable for candle-related creations because of their heat and fire resistance, but it also notes that its sealers are not fireproof. 

Which one should I choose for planters or soap dishes?

AC730. Jesmonite specifically recommends AC730 for pieces that come into regular contact with water, such as soap dishes and plant pots.