bit.ly/Park-Royal-Clay-Testing

<aside> 🧱 This page contains some of the results from my experience testing the wild clay extracted from Park Royal. This clay has been extracted from the construction site where a new train station will be built. The station will be part of the new HS2 system.

The page will be constantly update as I gather more information about this clay.

created by: Victor Pedrosa contact: studio [at] victorpedrosaceramics.com last updated: 15 October 2023

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What you will find on this page

Pre processing

All test tiles went through the same process before being shaped into long tiles. To process the clay, I used the following steps:

  1. Breaking: Cut the clay into small chunks
  2. Drying: Dried the clay completely – this clay seems to take quite a while to dry
  3. Slaking: Soaked the clay in water and left for a couple of days
  4. Mixing: Mixed the clay and water thoroughly
  5. Sieving: Sieved the liquid clay through a 100 mesh sieve (if there too much water, you may want to remove some of the excess water)
  6. Hardening: Poured the clay onto a plaster batt and let it harden for a day. This stage is not performed if the clay is to be used for slip casting.

Park Royal Clay and slip casting

For some of the tests, I used the wild clay to make a slip for slip casting. For that, I stopped the pre-processing at stage 5 and adjusted the thickness of the clay by adding or removing water from it. To reduce the water content, I left the slip to rest for a couple of days and waited for the contents to separate. The top layer of water can then be easily removed.

I tried to adjust the specific gravity and viscosity by adding deflocculants, but this process failed with all the sodium deflocculants I tried (from Potclays and hot-clay). The addition of deflocculant would either result in no change at all or would completely gel the slip. This indicates that the clay as it comes is not well suitable for slip casting. This can probably be fixed , but it needs more testing.

I used the clay with a very low specific gravity (around 1.1-1.2) to slip cast over a hundred cups, but the high amount of water meant that pieces would take a long time to dry and detach from the mould (over three days at some point). The video below shows a very short video with part of the process of making the cups.

https://www.instagram.com/reel/ClD418cD0Tc/?utm_source=ig_web_copy_link&igshid=MzRlODBiNWFlZA==

Firing results