Mouldy casting!!

Molding and casting

We decided to use Mold Max 30 for the final product. This is the corresponding safetysheet. The productinformation for Mold Max 30 says that it is compatible with wax, gypsum, low melt alloys/metals and urethane, epoxy or polyester resins. For the mold we will use Vytaflex 50, a urethane rubber that is flexible. Here's the safetysheet. To be absolutely sure Mold Max 30 doesn't react with Vytaflex we decided to pour Mold Max 30 on the Vytaflex 50 test we ran on the Sad Candy design we made with Bas on thursday.

To pour the Mold Max 30, you need vinyl gloves, long sleeves, air ventilation and safety glasses. The pot containing the silcone rubber comes with a flask of curing liquid. The ratio to pour the two is 100:10. You should use a gram scale for this. The reason why it doesn't say 10:1 is probably because of accuracy. It does matter if you pour 10:2, it doensn't matter if you poor 100:11. The product information recommends vacuuming.

To pour the vytaflex 50 you also need gloves, long sleeves, safety glasses and air ventilation. The ratio to pour the rubber (Part A)with the curing liquid (Part B) is 1:1, either volume or weight. Both liquids should be stirred well first. After this we made an estimation of the total amount of rubber needed for the mold. We filled the mold's mold with water, poured it a cup an weighted the water on the scale. We measured 33 gram, which is 33 milliliter. The safetysheet of vytaflex says Part A has a Specific Gravity of 1.04. Part B has a SG of 1,05-1,25. Water at 4°C has a SG of 1. So Part A and B have a slightly higher density then water. To get the same volume of 33 grams of water, we need 1,04*33/2 = 17,15 grams of part A and 1,15*33/2 = 18,98 grams of part B. But as we need a ratio of 1:1 and both materials don't come fully of the pouring cup rims, we used 20 grams of Part A and 20 grams of Part B.

The Lego patch gone boink.
Johanna casting
David watching Johanna casting

Further observations:

PMC 121

Vytaflex

Smooth-cast 305

We looked at the safety sheets. In Vytaflex it lists "Acute toxicity, inhalation-Category 4 ", so we googled that, to see what it means. The American EPA had this document, which stated two different systems for toxicity. The GHS (Globally Harmonized System of Classification and Labelling of Chemicals), and OPP (Office of Pesticide Programs, we think). Both have different inhalation toxicity levels, so it is unclear which the safety sheet is talking about. Can we just assume that it's bad for you if you breathe it in?

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