Hi,which is the hardest water or crystal clear resin.I need to make some jewelry,at the moment i'm usibg Aldax hard epoxy casting resin,but it is not hard enough for polishing.thsnks
Crystal Clear 220 is the hardest; but it requires a heat cure cycle. Smooth-On's standard Crystal Clear 200 is an 80D and this can be polished no problem and does not require a heat cure.
Let me add that deairation is mandatory, else you will be looking at a clear cast full of bubbles. With a heat cure materials the bubbles could become larger.
Thats true, vacuum degassing may be necessary depending on what the tolerance is for bubbles in the application. And typically with clear casting applications bubbles are NOT desired at all.
The alternative is the pressurize the casting while the material is liquid in the mold. By doing so, the air bubble is shrunk until it is not visible, then the material cures.
Some people do both processes - vacuum degassing and pressurizing. Of course both processes enatil using extra equipment, which may be costly depending on the size & scope of that equipment.
And if using the heat-cured version, then the set-up needs to have heat capabilities - an autoclave is most common where you can apply pressure and heat.
Ultimately it boils down what the objective is with the casting and how much money one wishes to spend on extra equipment if needed.