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Hi all, I've got a few questions regarding the 'new' product 'XenCast Flexible Polyurethane Rubber' advertised on your website. Basically I'm making a couple of moulds with the intention of casting 'Vac-Cast Epoxy Resin' into them, what I need to end up with are two perfectly reproduced tooling plugs for vacuum forming my final parts into ABS plastic. The following image will hopefully explain in greater detail my procedure. I've recently used a product from 'Smooth-On' called 'OOMOO 30', but had a disastrous result. I must admit, as good as it seems to be I just hate working with it. Here's what my original mould box looks like with my plug secured in the base, I then poured the silicon rubber into the mould box ......... it was an awful lot of work, trying to mix what was a consistency of partly molten lava, and the impossibility of pouring made the job needlessly difficult, the result was a failed pour and a very badly formed mould ! >>  Pouring the mix in a thin stream in a low corner was just impossible, I almost had to resort to 'trowelling' it in ! >>  When I demoulded the following day, it wasn't too bad, but strictly speaking an appalling result. Not something I would want to cast resin into that's for sure ......... I put it down to a good learning experience >>  Because the silicon rubber wasn't 'fluid' enough, full coverage of my plug wasn't achieved, leaving large voids and air pockets >>  So basically, my question is, would that 'XenCast flexible Polyurethane rubber' be an alternative to OOMOO 30 ? I've been looking at the 'XenCast PX30', it seems to have the same characteristics as the OOMOO 30 ( both Shore A of 30 ), how will it react to Vac-Cast Epoxy Resin being poured into it ? |
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Group: Forum Members
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Thanks for your continued support Hanaldo, very much appreciated. I know this forum is oriented toward carbon fibre, laminating, resins and vacuum bagging, so some of my questions may seem of little or of no relevance to what is usually discussed here. But the mould creation and preparation is still the same, once I have my moulds complete the procedure is different, agreed .......... but the vacuum forming stage using sheet plastics is only slightly different, whereas you guys would 'form' your final parts using fibre glass or carbon fibre. The 'CS2' product I've been asking about has actually been superseded by 'CS25', a new formula I believe. I will be placing an order for it, after all, it is definitely worth a try, it's so much more cost effective creating flexible moulds than 'OOMOO 30' .......... that mauve 'blob' you see in the images above cost me €196.00 !  from the first instant that I removed the lid from the silicon and began to pre-mix the contents, I knew there was something up .......
Before I plan on using a particular product I research everything ( as I'm doing here with the CS25 ), one of the videos I saw was this one. The interesting bit begins at 0:54 where he's already pre-mixed it and begins the pour >
So after seeing that I new that was the stuff for me, judging by the shape and size of my mould. The actual completed silicon mould will only be used to once, as it's for making permanent vacuum forming tooling plugs. I'll be using 'Vac-Cast Epoxy Resin' for that, as it's specially formulated for vacuum forming applications. Imagine having a bucket of tooth paste ....... now imagine trying to mix it with a wooden mixing stick ! ........... there's no way you can mix that, let alone pour it in a nice thin stream 
I've since then emailed the company who produce it, 'Smooth-On' ........ awaiting reply. Also I've emailed the company who sold it to me ...... waiting on reply.
As with any product like this, including resin, there is a shelf life. But one would assume that the shelf life ( if correctly stored, as mine was ) that the shelf life would be extended, like six months to a year. As opposed to a product that been opened, once the air gets in you have to use the remainder of the product as quick as possible. I've spent the entire weekend reading gibberish on every single website I could think of who may be using something like this. And then I found two guys who had the exact same problem as me ! ........ even if the product remains unopened, it goes off ! the longer you store it, the thicker it gets.It must be used right away ......... and the recommendation is when placing your order is ask for a new batch.
You live and learn  .......
I'll be placing my order for CS25 at some point today, I'll let you know how I get on if you're interested.
While I'm there ( @ EC ) I may as well order a degassing system from them ........ been chatting to Warren, apparently they've got a new system in  |