More on polymer-modified plaster

Good news I hope for anyone wanting to take advantage of the properties of Jesmonite but unwilling to pay such an inflated price! For some time now I’ve recommended using Tiranti’s Plaster Polymer liquid together with a regular ‘alpha’ plaster such as Crystacal R or Basic Alpha. Similar results can be achieved with these at less than half the cost of the Jesmonite system. But recently I had the chance to test Specialplaster’s own SP201 acrylic polymer, with very promising results .. this time for less than a quarter of the price! I’ve written up these tests in the ‘Worklog’ at the end of Polymer-modified plaster in the Materials section under ‘casting’. I’ve also looked into whether the liquid and plaster components of Jesmonite can be combined with others, i.e. using the Jesmonite ‘powder’ with a different polymer or the liquid with other plasters. Judging by the few tests I made the answer is ‘yes’ .. but with some surprising results!

Making a mould jacket

These are photos from the ‘Worklog’ featuring a mould jacket I made using the SP201 and Crystacal R plaster, reinforced with jute scrim. I took the risk of using only two layers of jute scrim, because I wanted to see how this compared to Jesmonite for strength. As it turned out it was more than strong enough, even though the shell can’t be much more than 3mm thick!



2 thoughts on “More on polymer-modified plaster

  1. Hi, what a wealth of information here, thanks a bunch! My question may be a little strange, but I’m guessing I couldn’t ask a more knowlegeble person. I have hollow mirrors on my motorcycle that vibrate so bad I can’t see images in them. I have drilled two holes in the aluminum housing, one at the top and one in the bottom. My intention was to mix some plaster and inject it into the top of the housing behind the glass mirror, letting it drain out the bottom as necessary to prevent trapped air. . This should add weight and dampen vibration. In combination with some mods to the mounting arm I think this will do the trick. I stopped just before adding the plaster because I wondered what else there is that is heavier/denser than plaster of Paris, that I could use. Ive just learned of the existence of marble powder thanks to you, but don’t know if this would be much heavier than the plaster? I’d like to use the densest nonconductive substance I can find so as to maximize the effectiveness of this whole effort. What suggestion(s) might you have?

    • Hi,

      Cement would probably be better and heavier I think .. though if you hadn’t said ‘nonconductive’ I would have said iron powder (filings) mixed with resin could be heaviest. I can’t help you with the second question .. no ideas I’m afraid .. I’m taking a break from this for a while, can’t really afford the time at the moment

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