Page 48 - BSAM 2016 Q4

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G Place a sheet of thin, transparent plastic or lm over the mold and trace the stone outline with a thin pointed permanent marker. en you need to mark depth points on this same piece of lm that will accurately re ect the shape of the base of the mold. I have 81 marker points for this small, 13 cm x 8 cm stone. To make sure the lm does not move while you are making your marks, you can x it to the mold with double-sided tape.
H Trace the outline of the stone on the block of wood for the base by using carbon paper under the lm outline and a pen or a stylus with a hard tip. Set aside.
I en place a piece of rigid Perspex* about 3 mm thick over your lm and mark both the stone outline and the depth mark points onto the Perspex, again using a thin pointed permanent marker.
J For my depth markers, I use cotton tips with one end cut o , so select a thin drill bit of equal thickness as the cotton tips and drill holes at every marker point you have indicated on the Perspex.
Now place the Perspex on top of the mold and line it up as accurately as you can with the stone outline. Again, holding it in place with double-sided tape so it will not move would be good.
1) With a bit of practice you will get this next bit done success- fully! Take a cotton tip with one end cut o and place it in the rst hole so that it is vertical and touching the base of the mold. Mark the cotton tip at the point where it meets the top of the Perspex. Set the cotton tip aside in some way that you can place each successive tip in order for the next part of the process. To keep track of mine, I use a piece of tape, sticky side up, on a thin strip of timber and press each cotton tip onto it in sequence.
If you look at the photo of the Perspex tracing you can see that I have placed my depth marker points in rows and numbered the starting point of each row. This allows me to keep track of the markers, in this example, 81 of them.
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| BCI | October/November/December 2016