Video Instructions:

Written Instructions:

1. Clean the VAT

Having poured out the resin and peeled off the old PDMS wash in a bowl of warm soapy water, I used dish washing liquid and a sponge that will not be used for food. Once clean rinse with clean water and allow to air dry.

2. Mix silicone

You need to mix up 45-50g or 45-50ml of Sylgard 184. This has a 10:1 mix ratio (weight or volume) between the silicone and hardener. So that means 45.45g or ml of silicone and 4.54g or ml of hardener (for 50 ml total).

Mix these in a clean container, I recommend a fresh plastic disposable cup. You need to mix them well and I suggest a plastic stirring stick (cocktail stirrer or similar), metal may scrape plastic into the mix (been there done that) and wood may lose splinters into the mix.

3. Pour the PDMS

Pour the PDMS into the deep end of the vat. Tilt the vat as required to ensure the whole of the deep end is coated and tilt it to let the PDMS flow into the shallow end and ensure that all of the bottom surface of the that end is also coated.

At this stage there should basically be no dry parts to the bottom of either side of the vat.

Now tilt such that most of the resin is in the shallow end, it is OK if it gets a bit high up end wall.

Now set on a level surface where it will not be disturbed, cover with something to keep out the dust (the best bet is a clean plastic tray that covers the whole vat) add a "DO NOT TOUCH" sign and leave for 48hrs to cure. During curing some of the PDMS flows from the shallow side back to the deep leaving a nice smooth transition.

If you have a hot box or lab oven you can heat to cure, follow the instructions for the PDMS but avoid temperatures above 180 degrees F. or the acrylic may warp, you must ensure that it is level (and lots of ovens are not.)

(Thanks to Graham on the forums)