Sedimentary Rocks

Sedimentary Rock 1-5 are five compositionally different sedimentary rocks. Unfired, solid, and imperfectly cast I drew upon the concept of replicating the same form over and over again.

What is a Sedimentary Rock?

As the name suggests, sedimentary rocks are made from a variety of different sediments that cement, over time, together. There are three categories of these types of rocks: clastic, chemical, and organic. When you think of sedimentary rocks, you are probably thinking of the clastic group. This category is characterized by pieces of pre-existing rock material settling together and eventually sticking together. Because this group is so widely understood for what it is, I decided to focus on it to make my own.

Materials Used

I didn’t keep track of which rocks used which sediments so here is a list of ones that I remember using:

  • clay (porcelain + low fire)
  • mason stain (pre-fired minerals crushed into powder)
  • sand (Canon Beach, OR)
  • alabaster sand (pink, blue + green)
  • alabaster powder (pink, blue + green)
  • fired brown groggy clay (sand)
  • water

Proccess

The first step in manufacturing these imperfect sedimentary rocks was to make a mold of a rock. I went outside the studio and, of course, because I was in Utah, there were plenty of rocks to choose from. For those of you who have never been to Utah, they use a lot of rocks in their landscaping. After choosing a lovely landscaping rock it was time to wash and prep it for plaster. Prepping involved rubbing it with oil-based clay to get rid of any ridges or undercuts I didn’t want.

Plaster + Slurry

Once that was finished I made a four-part plaster mold of it. I allowed each piece to dry and then it was ready to use. (Side note: I ended up making another mold a couple of months later, so I had two overall).

Next up was making a slurry. There was no rhyme or reason to what I used, aside from the fact that I had to use already pre-existing sediments (mixed with water). Scratch that, I did have an idea of why I wanted to use alabaster.

Alabaster

Back in 2017 I had crushed alabaster and turned it into sand and powder for another project (glaze testing). That summer I returned home for two years along with a bucket of said alabaster. Over that two-year period, I had discovered that the alabaster settled enough to form a very strong solid mass without any promptings from me at all. Anyways, this is why I wanted to use it to make these rocks (strong natural cementation).

Casting

Once the slurries were made and the molds were dry I could cast these rocks. Casting involved putting the molds together and funneling the slurry into the mold then leaving for a couple of hours to dry (I still had classes I had to attend). When I came back I topped off the slurry and let it dry all the way.

Unmolding

Unmolding was always really fun. It was the big reveal after waiting a couple of days for it to dry completely. Plus there were always unexpected cracks and textures which I loved. However, sometimes the results were underwhelming and in that case, I would reintroduce water to the rock and allow it to become a slurry again. I would then play with the material more until I cast something I liked.

Revealing the Sediments

The last step was to wipe away or sand away the outer layer to reveal the sediments laying within. Once again, this was one of my favorite parts and it’s super hard to capture through the camera! The different types of sediments used gave off some sparkle or contrasted beautifully with the matte parts of the rock.

Sedimentary Rock Shortcomings

These rocks point towards more of my own shortcomings than the limits of the earth. For example, if I submerged these rocks in water they would dissolve, their impermanence being visible, while the earth continues to make stronger sedimentary rocks. The difference here is millions of years in comparison to a couple of months of my own time.

So did I really make ‘true’ authentic sedimentary rocks? My answer is kinda. They weren’t as strong as they could be but I didn’t have access to an industrial pressure chamber so I did what I could.