This is my method for creating your own gravel using plaster.
I know what you all are thinking. “Why not use real gravel?”
There are several reasons to use plaster over real gravel. One is weight. Cured plaster weighs about half as much as most stone.
Another reason is color control. When designing a habitat display I often will need to use artificial rocks to hide hardware. I personally would rather go all artificial or all natural.
Using plaster will help me is unifying the entire composition by controlling the colors and pigments I use.
The final reason is, I often enjoy the ability to replicate all aspects of nature in a display, this includes the gravel.
So before we jump in this is what you will need.
An electric drill
A bit for a kitchen mixer. (I get mine at thrift shops)
A few mixing containers
Some netting or wire mesh for sifting the gravel.
Here is the idea.
Plaster normally takes 20 minutes to set, but Heat will speed things along.
So we use warm water, and a fairly dry mix.
The next trick is motion, We wont let the plaster rest and will be mixing throughout the setting process. The friction of the mixer will speed the setting even more.
In five minutes we will have a bucket of gravel!
Lets get started.
Here is my mixer and my drill.
Normally it will fit right in, but sometimes you will need to grind down the tabs on the shaft.
Here is the drill set and ready to go. Remember this wont work without the drill.
For this batch I used a cup of warm water. (More on the hot side of warm)
I added enough plaster to let it mound over the water. (The goal is to form a dough rather then a smooth mix)
And off we go!!!
As we mix we will be adding more plaster. We want it to be dry and to start to clump up.
As we add plaster and keep mixing the “rocks” begin to form.
After about three minutes and a few half cups of plaster this is what we have. (It is actually warm enough you can feel heat coming off of it)
Next I got some netting so I can sift the dust off of the gravel.
I taped the netting to another pail.
I then sifted the gravel over this pail to clear the dust. You can also use several buckets with different sized netting to separate the sizes.
And there we have it. Gravel!!
Let it sit a day or so to dry, then we can paint it.
I normally use acrylics that have been diluted with water. The plaster will absorb the colored water and will look very natural.
Here is a short video that shows the whole process. It really doesn’t take long to do.