Concrete Relief-Cast Botanical Specimens

Isn't nature amazing?! Do you wish you could capture it 'forever'? YES you can! In a couple easy steps you CAN capture it in concrete!

I have worked in concrete for many years and have designed very unique projects but this one is so impressive for a small amount of work and readily available supplies!

• Botanical Specimens (look closely to find ones that have a good structure and thickness works best)
• 100% Silicone Caulking ( Silicone Caulking #1, not #2)
• Cornstarch
• Bowl for mixing
• Gloves
• Rolling pin
• xacto knife
• Concrete Mix (this is a special strong one)
• frame shape for pouring concrete
• mixing container (flexible is best) & mixing stick
• wire for hanging loop
• plasticine (opt)
• acrylic paint, medium, brushes etc

This method does not involve making a plaster cast first as I did in this tutorial. That works as well but has extra expense and more steps. This does however mean that you will be jumping right to the mold-making step.

Before making the mold mix plan your Botanical specimens as you will not have time later. Also get the rolling pin ready. A sheet of some clear plastic (like from a package), or some parchment paper helps keep from sticking to rolling pin.

This recipe for making a silicone mold works really well! I have used it in many projects. It does sometimes take a bit of practice to get used to the mixing. I liken it to making a pie crust or bread dough. You do want to make sure it is mixed, not too sticky and not too dry. I do not measure as humidity can be a factor.

I used enough cornstarch to line a bowl and then squirt about half a tube of the caulking in the middle. Toss and toss and try to keep it in the cornstarch and not al over your gloved fingers. Pasta dough often starts like this in a mound of flour...

This mixture will cure really quickly so you do need to have all the material ready. Work fast...

Once you have a nice well mixed ball of 'mold dough' it is time to get it flat with the rolling pin. I decided to cut the outer shape afterward so I only was concerned with my arrangement of the plants. These are succulents so the are quite thick and detailed.

Place them on the 'Mold-dough' and cover with paper/board and roll with the pin. The plant will sink into the dough somewhat. You can do all at once or one at a time... I used this method when I cast an artifact mold and it worked great!

Whenever I use a new media I like to have a small test run. Then I can see how it reacts and what I need to know before I waste a lot.

After all the botanical species have been pressed well into the 'dough' wait until it has cured. When you press on the 'dough' it will feel like a solid rubber, then it is cured; it only usually takes minutes.

Pull the plants out fo the mold. If you need help use some toothpicks, pins or tweezers to get parts out. You will be amazed at the detail it captures. For my round mold I found a cake cover that I cut to make a frame for the casting. I cut my silicone mold to fit snuggly in the circle. Also place it where it is level before pouring.

Ok, before you go and get the cheap typical concrete make sure you know what you need! So many people buy the wrong kind since there are so many kinds. This post will help! Also, if you are nervous about working with concrete I have some tips for you!

I prefer the Rapidset Cementall mix since it is fine and strong and sets in one hour!!!

It does use little water so do not add too much at first. It should be like a thin gravy consistency to flow into the details. Stir well to make the bubbles come to the surface.

Pour into the well secured mold (use some plasticine if you want to hold mold and not loose any concrete) The problem can be bubbles! Tap and bang the mold to make the bubbles rise. Also using an old brush and working through the mix gets it into the small details

To make a hook to hang bend some wire to form a loop and imbed that into the concrete. Now it's time to wait... It goes fast!

This concrete mix sets and cures in one hour! It has no aggregate in it and is quiet fine texture so it is great in the mold.

When choosing the outer mold plastic is great as it is flexible enough to easily remove the concrete casting. I did not use a mold release as I find the concrete does not stick to the silicone. The succulents I used for this one have many small details and this concrete holds well in them.

Before you know it you will be looking at each plant for it's form! How amazing is that Bas-Relief or Relief cast as I call it... be creative, cast what you like!

If the edges are rough after casting you can use some emery cloth to just sand off the sharp parts. I like to do it underwater to make less dust.

I actually love them just like this, no colour - just great texture! With the grey interiors this give a sophisticated look! (Pssst; If you want one of you own)

As an illustrator I do like colour if I get to have fun with it. The Creeping sedum has an shades of red so adding a bit of acrylic paint is easy since it's already raised.

Paint the leaves and petals with a thinned acrylic (thin with acrylic medium to maintain the water protection) and use reference for the colours. Do not use the colours right from the tube, try to mix interesting colours that mimic nature. If you'd like more details check here

One of the best ways to get textural details to stand out is to use some sort of antiquing. Making a very thin dark 'wash' will give the recessed parts some depth. Wipe away the excess quickly so that it does not cover the highlight details. I learnt ths technique many years ago when I would paint beerstein greenware.

Side by side - colour or not?

If you like this relief casting there are also methods where you use a plaster cast first. Any way you want; it's a great way to capture nature and design with it!

I ❤️ working with concrete! The possibilities are endless - Check my site