If you've been exploring Jesmonite®, you've probably come across products like Retarder, Thixotrope, Super Plasticiser, or one of the sealers and wondered:

"Do I actually need these?"

The short answer? Not necessarily.

Jesmonite® AC100 and AC730 are designed to perform beautifully on their own. Most projects can be mixed, poured, demolded, and enjoyed without adding anything extra.

Ancillary products simply help you customize how Jesmonite® behaves. They solve specific challenges, extend your working time, improve flow, protect finished pieces, and open the door to techniques that wouldn't otherwise be possible.

Think of them as specialty tools. You probably won't use every one on every project—but when you need one, you'll be glad you have it.

Here's a simple guide to help you choose the right ancillary for your project.

"My Jesmonite® is setting too fast."

If you've ever felt like you're racing the clock while mixing a large batch or filling an intricate mold, you're not alone.

Jesmonite® is known for its quick curing time—which is great for productivity—but sometimes you simply need a few extra minutes.

The solution: Jesmonite® Retarder

Retarder slows the setting time without affecting the finished strength or appearance of your project.

It's especially helpful when you're:

• Working in warm weather
• Mixing larger batches
• Filling highly detailed molds
• Creating layered or laminated projects
• Teaching workshops where participants need more working time

Both Jesmonite® AC100 and AC730 have their own Retarder formulations, so be sure you're using the one designed for your material.

"My mix keeps running off vertical surfaces."

Some projects require more than a pourable mix.

Maybe you're applying a gel coat, repairing a chipped piece, or working on a vertical surface where standard Jesmonite® simply won't stay in place.

The solution: AC100 Thixotrope

Thixotrope thickens Jesmonite® AC100 into a paste-like consistency, giving you much more control.

It's perfect for:

• Gel coating molds
• Building up layers
• Vertical applications
• Filling chips or small repairs
• Joining laminated sections

A little goes a long way, so start with a small amount and gradually build to your desired consistency.

"My AC730 is too thick."

Jesmonite® AC730 is a micro-concrete, so it's naturally much thicker than AC100.

Sometimes that's exactly what you want.

Other times—especially with detailed molds—you need it to flow a little easier.

The solution: AC730 Super Plasticiser

Super Plasticiser (aka Super P and one of our personal favorites!) increases the flow of AC730 without sacrificing strength. 

It's ideal when you're:

• Filling intricate molds
• Casting larger projects
• Trying to reduce trapped air
• Looking for cleaner surface finishes
• Pouring thin architectural pieces

Unlike adding extra liquid (which should never be done), Super Plasticiser improves workability while maintaining the proper mix ratio.

"Do I really need to seal my project?"

This is probably the question we hear most often.

The answer depends on how your finished piece will be used.

If it's purely decorative and lives indoors, sealing is often optional.

If it's going to be handled frequently, exposed to moisture, or sunlight sealing is highly recommended.

So which sealer should you choose?

Choose Matte Sealer if you want a natural finish

Jesmonite® AC100 Acrylic Matte Sealer protects your project while preserving its soft, stone-like appearance.

It's a great choice for:

• Coasters
• Soap dishes
• Decorative trays
• Sculptures
• Projects where you want protection without added shine

An added bonus? You can even tint the sealer with Jesmonite® liquid pigments to create subtle washes and patina effects.

Choose Gloss Sealer if you want colors to pop

If you've spent time sanding a terrazzo project, you already know the magic moment happens when the colors come back to life.

Jesmonite® Gloss Sealer is compatible for use on both AC100 and AC730 projects and it enhances color depth while adding a durable protective finish.

It's perfect for:

• Terrazzo projects
• Brightly pigmented pieces
• Decorative home décor
• Functional items that need extra protection

Multiple thin coats create the best finish.

Choose Flexiguard Sealer for AC730 outdoor projects

Jesmonite® AC730 has a beautiful concrete-like appearance, but like concrete, it's naturally porous.

Flexiguard Sealer protects the surface from:

• Water
• Stains
• UV exposure
• Everyday wear

Best of all, it does this without changing the natural look of the material, making it ideal for planters, tiles, countertops, and outdoor décor.

Quick Reference Guide