The following experiment was conducted in my home, with as much care taken as possible to ensure consistency between the trial groups.
The purpose of the experiment was to see how translucent clay responds to different curing processes. There were 4 groups. Group 1 was the control group. Group 2 was buried in cornflour. Group 3 was buried in cornflour and then dunked into cold water straight after curing. Group 4 was cured uncovered and dunked in cold water straight after curing.
I made up a simple cane of turquoise clay surrounded by Kato translucent clay. I cut 4 x 5mm slices, then used 2mm slices to cover a core bead of turquoise and translucent mixed together (cane ends LOL). The core beads were all the same size.
All the pieces were cured in my toaster oven at 275 degrees F for 30 minutes. Group 3 and 4 were dropped into water that had chilled in my freezer for 30 minutes (while clay cured).
As soon as beads were touch cool I took photographs and noted my impressions.
I then sanded each piece with 400grit, 1200grit and 3000grit wet /dry sandpaper and buffed with a dremel.
I then rephotographed and noted my impressions.
I will note now that I was surprised by the end results – they were not exactly what I had been expecting. It is also worth noting I used Kato translucent – other translucent clays may well perform differently under the same conditions.
The simple cane we started with, with the clay for the bead cores at the back.
- Our four groups on a ceramic tile covered with paper.
- Our four groups ready to go in the oven.
- Groups 3 and 4 in cold water straight out of the oven.
- Groups 1 and 2 just out of the oven.
Group 1 – Had a weird orangey hue and sort of ‘ooze’ on the surface of the clay. It was also very ‘shiny’.
Group 2 – Very white in colour – as white as the uncured clay of the cane. Surface was very smooth with none of the ‘ooze’ of group 1.
Group 3 – White, but not as white as group 2. It seems ‘clearer’, but not hugely. There was none of the ‘ooze’ of group 1.
Group 4 – There was a slight orangey tinge and a little of the ‘ooze’, but it actually seems to be more translucent than the rest.
After sanding and buffing.
Group 1 – Slight discolouration, a little orangey or yellow. Medium ‘cracking’, mainly long cracks. There is ‘translucence’, but with a orangey tinge of colour.
Group 2 – No discolouring, very white. Medium ‘cracking’, very similar to group 1. Some translucence, but less than group 1.
Group 3 – No discolouring, but not as ‘white’ as group 2. Lots of little ‘cracks’, more than group 1 or 2. Translucence is about the same as group 1, but without the tinge of orange.
Group 4 – The discolouring noticed after curing is almost completely gone after sanding, although it isn’t as ‘white’ as groups 2 and 3. Lots of little ‘cracks’ like group 3. The best translucence of them all, but not by a huge amount.
Not the best shot of the differences in translucence, but hopefully will give some idea. Groups are in numerical order as in picture before.
Picture of ‘cracking’ on the beads. Every attempt was made to ensure no air bubbles were present in clay – these cracks are unlike the cracking caused by air bubbles. Groups are in same order as before.
Cornflour prevents the discolouration of the clay, although if you plunge it into cold water after curing the discolouring seems easier to sand off.
However, plunging it into cold water seems to induce more of the ‘cracking’, which could be very useful if making faux gemstones.
2mm thick slices are too thick for the really translucent look.
In my opinion, although the plunging in cold water alone seemed to give the best result, for a result without discolouring, bury in cornflour and then plunge in cold water.
I hope this has been as interesting to read as it was to do.