The PUR casting resin is something very special: it is extremely soft and elastic while also being colourless and highly transparent. Because it contains UV stabilizers it can be exposed to the sun for long periods of time without yellowing. Its Shore hardness and elasticity can be varied by adjusting the mixing ratios. When less hardener is used, very soft and elastic pieces will be created. These will have good adherence properties by virtue of being made up of thin layers and having a very smooth, even surface which will adhere well to other smooth surfaces like, for example, glass.
This casting compound is therefore great for making crystal clear shaped pieces (see. BUMPONS), which can be cast to a wall thickness of 20 mm. In addition, this material can be used as a soft and transparent coating.
Both components are predominantly made up of sustainable raw materials. They consist of olive biopolyols and caprolactones as well as small amounts of isocyanate. The components, which are pretty much odour-free, are therefore non-toxic (safety label not required). The 1770/330 is easy to work with - when making a mixture, it should be noted that the hardener should be measured out first and the resin then weighed accordingly and subsequently mixed into the hardener.
Dyes suitable for use with PUR resins can be used to colour the 1770/330. In doing this, the dye must be mixed into the resin component (up to 3% proportion by weight of the resin) because the hardener is the component containing the isocyanate, which reacts more sensitively to the addition of other substances.
In order to produce cast pieces that are free of bubbles, the resin should be de-aerated in a vacuum - especially if it is not being dyed. If no vacuum device is available, it is recommended that you at least use the pot life period to de-aerate the mixture. This will, however, not really produce a crystal clear, bubble-free result - but will get somewhat closer to that anyway! After demoulding, the cast piece should be tempered at 80 °C for between 2 and 8 hours. Once cured, the resin is scratch resistant and lends itself to being machined , sanded and polished.