PU600 High Density Polyurethane Model Board

Unfortunately none of our tooling boards carry any Fire Retardancy or Fire Rating certification.

Yes you can bond the sheets together. We recommend our Fast Cast Polyurethane Casting Resin for bonding this pu600 density board. The resin can be spread over the surface of the block and will cure very quickly and make a good strong bond that will machine in a similar way to the board itself.

It's possible that you might be able to use petroleum grease as a basic release agent but generally this wouldn't be our recommended approach. The problem with petroleum grease is that it's so soft and 'mobile' that it can be quite easy for it to accidentally thin out in places to the point where it wouldn't be effective. If you apply it thicker, which would generally be better from a release perspective, then you're likely to find that your castings have quite visible 'smears' and other unwanted surface detail caused by thicker areas of the grease.

A more permanent and reliable long-term option would be to use a board sealer, such as S120, and then several coats of Easy-Lease chemical release agent.

Although the board itself is waterproof and unlikely to be damaged by water and the environment, the open structure on the surface means it is likely to pick up dirt and debris quickly. As such it is recommended to seal the surface with a paint or protective coating to improve and prolong the surface appearance of the board.

No the board will not swell as it has a closed cell structure and thus very limited moisture absorption would occur.

In terms of sealing the PU600 board so that RTV silicone rubber will release from it, this might not actually be necessary because the density of the PU600 board is sufficient to mean it has a smooth, closed surface structure. Since RTV silicone doesn't stick (other than slightly grip) to most materials, including PU board, you would be able to peel the RTV silicone off the PU board even if you did no surface prep at all.

If you would like to improve the surface of your pattern/master - for example to achieve a smooth high gloss finish - then you could use either our S120 Board Sealer or our Pattern Coat High Gloss products. The board sealer would be better if you already have a very fine finish on your pattern/master whereas the Pattern Coat product is higher build and would be more suitable if the machining/finish on the pattern/master needed more work.

In either case, you would not need to use a release agent afterwards, silicone will release itself from both of these material surfaces.

Yes our S120 is suitable for use on Polyurethane as well as epoxy tooling/modelling boards.

No, this PU Model board is not suitable for lost foam casting methods that require you to dissolve the foam. Acetone will not dissolve PU foams or model boards. Also this is a very high density model board rather than a light foam that is normally used for these kind of methods on practicality grounds. Typically, polystyrene is used for such methods as it can be easily dissolved out of the finished tube.

Yes, you can do this, exactly as you describe. Although you can’t really tell it’s happening, Easy-Lease does build-up on the surface of a mould (or pattern) with its solids content. This solids content is what will seal the PU600 and allow you to release from it but to get a good, glossy finish and reliable release you will need to apply a reasonable number of applications. I would suggest that in the region of 10 applications of Easy-Lease, at 10min intervals, will give you a nice, well-sealed, shiny mould surface from which you can reliably release.

The only extra piece of advice I should give you is that you should not use PU600 as a mould for prepregs; when polyurethane gets hot it will inhibit the cure of prepregs significantly. PU600 as a mould, should therefore, not be used for prepregs; epoxy tooling block is required in this situation.

The PU600 model board is polyurethane based and this will inhibit the cure of any epoxy based pre-pregs thus making it unsuitable for most autoclave use. The PU580 has a heat distortion temperature of 85°C which reduces its use at higher temperatures. As a direct moulding material (rather than as a pattern from which a high temperature tool would be made) you would need to use either epoxy tooling board or ceramic tooling board.