How to Make a Jesmonite® Vase for Fresh or Dried Flowers

Not sure how much to mix? Use our free Jesmonite® calculator — enter the water weight of your mould and it gives you the exact liquid and base amounts.

Dried flowers or fresh?

Before you cast anything, decide what kind of flowers you want to display, because it changes how you finish the vase. This is the single most important decision in the whole project.

Dried or faux flowers are the easy route. They never touch water, so your vase does not need any waterproofing at all. You can cast it, cure it, and pop your stems straight in. This makes dried arrangements perfect for a first attempt, and they suit the soft, matte, stone-like surface of Jesmonite® beautifully.

Fresh flowers are where you need to plan ahead. Jesmonite® is a mineral-based material and it is naturally porous, which means bare, unsealed Jesmonite® will slowly soak up water and let moisture seep through the walls. Left standing full of water, an unprotected vase can weep, stain the surface, or sit in a damp ring on your furniture. The good news is that this is easy to solve, and we cover two reliable methods further down.

If you are still choosing your material, AC100 is the go-to for indoor decorative homeware like vases. It is beginner-friendly, non-toxic and solvent-free, which makes it a lovely material to work with on the kitchen table.

Choosing a vase mould

Your mould shapes everything, so it is worth a moment’s thought. Browse the vase moulds and think about how you will use the finished piece.

• Bud vases and narrow shapes are ideal for one or two dried stems and use very little material.
• Wider, open shapes suit fuller fresh arrangements, but remember a wide opening needs a wider insert to hold the water.
• Consider the neck. A gentle taper is more forgiving to demould than a tight, deeply undercut shape.

Most silicone vase moulds are flexible, which makes demoulding straightforward. If you are weighing up different shapes and finishes, it helps to look at the whole moulds range so you can picture the piece on your shelf before you commit.

What you’ll need

Gather everything before you start mixing. AC100 gives you a comfortable working window of about 10 to 15 minutes (a little less if the room is above 25 °C), so having everything to hand means you can pour calmly instead of hunting for a spatula halfway through.

• A silicone vase mould
• AC100 Jesmonite® base and Jesmonite® liquid
• Accurate digital scales (this matters more than anything else)
• A mixing cup, and a spatula or stirrer
• Optional pigments to add colour
• An acrylic sealer and, for fresh flowers, a glass or plastic insert
• P150 sandpaper and a sanding block for tidying edges

New to casting and want it all in one go? An AC100 starter kit bundles the Jesmonite® base, Jesmonite® liquid and essentials so you can skip the guesswork and start creating.

Working out how much you need

A simple trick saves waste, and for AC100 you can work it out straight from the mould. Fill your empty mould with water and measure the volume of water it takes to fill it. Add about 10% as spare, since some mix always stays behind in the cup, then divide that figure by 2 to get your Jesmonite® liquid amount. Multiply the Jesmonite® liquid by 2.5 to get your Jesmonite® base amount, because AC100 mixes at a ratio of 1 part Jesmonite® liquid to 2.5 parts base by weight. Many of our own mould product descriptions also list the amount you need, and you can double-check with an online Jesmonite® calculator or the Jesmonite® app. For a full walkthrough, see our guide on how much Jesmonite® you need. Either way, mix a little extra to be safe.

Step-by-step: casting your vase

1. Weigh accurately. Measure your Jesmonite® base and Jesmonite® liquid to the exact ratio, which for AC100 is 1 part liquid to 2.5 parts base by weight. Getting this wrong is the number one cause of soft, chalky or sticky results, so trust your scales, not your eye.
2. Mix thoroughly. Stir until completely smooth with no lumps or dry pockets. A high-shear mixer on a drill gives the cleanest blend, but a steady hand and a spatula work too.
3. Add colour if you like. A little pigment goes a long way, so add it gradually and stir it through fully before pouring. Jesmonite® is opaque, so pigments give a solid, even colour throughout the piece.
4. Pour slowly. Pour in a thin stream from about 10 cm above the mould to reduce trapped air.
5. Release the bubbles. This is the main way to avoid air bubbles: as soon as you have poured, gently tap and vibrate the mould so trapped air rises to the surface, then pop any surface bubbles with a toothpick. Only for moulds with a lot of fine detail, you can first brush a thin layer into the cavity, but for most pieces this isn’t needed. For larger pieces or very detailed moulds, a vibration plate makes releasing bubbles even easier.
6. Demould at the right time. AC100 is usually ready to release after about 30 minutes. Don’t leave it in far too long or it can “sweat” and mark, so aim to demould around the 30 minute point.
7. Sand, then cure. Smooth any seams or the base with P150 sandpaper and a block as soon as you have demoulded, while the cast is still relatively soft and easy to work. Then let the vase cure fully over the next 24 hours, during which it keeps getting stronger.

Making it hold water (seal it, or use an insert)

This is the part that decides whether your vase is a dried-flower piece or a proper fresh-flower vase. Because Jesmonite® is porous, an untreated vase should never be left standing full of water. You have two good options.

Option 1: seal the vase (recommended)

For a vase you want to use with water and fresh flowers, we recommend sealing it. Make sure the piece is fully cured, then apply an acrylic sealer in satin or gloss, building up even coats to protect the surface from water. Satin keeps the finish close to Jesmonite®’s natural matte look, while gloss adds a subtle sheen. Pay special attention to the inside walls and the base, and follow the coats and drying times on the product. Even well sealed, it is kind to your furniture to stand the vase on a small coaster or felt pad. For the full method, see our guide to sealing Jesmonite®.

Option 2: use a glass or plastic insert

If you would rather not seal, keep the water away from the Jesmonite® entirely: drop a slim glass test tube, a plastic tube, or a small jar inside the vase, fill that with water, and arrange your stems in it. The insert holds the water, the Jesmonite® stays dry, and you can lift it out to refill and clean.

Quick rule: dried or faux flowers need no waterproofing at all. Fresh flowers need either an insert or a properly sealed interior. When in doubt, use an insert.

Ready to cast your own? Explore the vase moulds to find your shape, and pair it with an AC100 starter kit so you have everything you need to make your first vase this weekend.