What is the shelf-life of Polyurethane?
Generally speaking, this is around three months. Beyond this period, potential moisture absortion can cause foaming. In turn, squirting a shot of Poly Purge into the can prior to releasing can extend the shelf-life of polyurethanes that have been opened.
How to create a 'shine' on an polyurethane item?
To do this, buff with a jewellery-polishing compound. Alternatively, polyurethane surfaces can often be retreated by cleaning then buffing. Or, you can apply/spray another polyurethane finish.
Up to what temperatures do polyurethanes tolerate?
Generally speaking (up to) around 70°C.
Painting Solid Cast 660 Polyurethane plastic
To do this, first, clean with warm, soapy water (or a solvent) then proceed with an enamel paint system.
Release agents for concrete casting into polyurethane flexible
Your best bet is a kerosene and oil mix. The rule of thumb is: one part oil to three parts kerosene.
Bonding Solid Cast 660 Polyurethane plastic
To do this, use Solid Cast 305 5-minute Epoxy Glue, Solid Cast 300 Epoxy Glue or Solid Bond 390 Superglue. Firstly, though, rough up the surface with sandpaper prior to gluing. This will help you achieve optimum results.
When flexible polyurethane rubber cast is still sticky after a few days of casting
Very simply, some flexible polyurethane rubber systems can take a few days to fully set.
When cured polyurethane is full of air and/or has hard foaming areas on the back
If this happens, it is often due to exposure to moisture, which in turn, causes polyurethanes to bubble and foam up. With this in mind, moisture can come from several sources (it's possible moisture was absorbed while in storage). Or, bubbles and foaming can simply be due to the product being near the end of its shelf-life (use Polypurge to extend shelf-life). The other issue is that the mould surface might be damp. In turn, you can dry it in a low-heat oven. Other reasons could be: possible excess humidity in the air on the day that you cast the polyurethane, or, if you've added a polyurethane mix, the filler may have been moist. In turn, fillers can be dried out by sprinkling on a tray and heating in a low-heat oven, ensuring that you allow to return to room temperature before adding to the polyurethane mix.
Solid Cast 6-55, flexible polyurethane rubber moulds
Despite their flexibility, these moulds must be waxed like a resin mould.