[PSUBS-MAILIST] epoxy domes

[Alan James via Personal_Submersibles]

I was a bit negative about this idea initially as I had played around with casting resins about 20 years ago.It was hard to get a thick cast without it cracking & therewas only one product on the market in NZ.Since then it's become popular for use on tables and in the art sector, with all sorts of properties being added to it.The one reference I could find to the refractive index of epoxy showed that it was better than acrylic.Be great if you could post some details on the product Hank so we can look up the material spec sheet.Alan

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  On Thu, 4 Aug 2022 at 11:52 pm, hank pronk via Personal_Submersibles<personal_submersibles at psubs.org> wrote:   Hi all,A friend has asked me to help him make a dome using epoxy casting resin.  I tried to discourage him, but his arguments have merit.I had him make a sample piece 2 inches thick and big enough to start testing.  The sample is amazingly clear.  I started by cutting and machining sample strips for bend testing as well as one pice to set out in the sunlight and one piece is stored in the shop.  So far to my surprise the epoxy machines as well as the acrylic and the comparison bend test with acrylic were also a surprise also.  Both the acrylic and epoxy had the same strength resisting bending and returning to normal.  I measured the bending movement with my magnetic base dial gauge and they were within .010 inch of each other.  The acrylic sample broke before the epoxy, by a good percentage.  I will repeat this test several times, but we are now making ports that will fit in my port testing chamber and do many pressure cycles and destruction tests.  This will give us a base line against acrylic.  If it works out we will make a small 2 inch thick by 24 inch dome and pressure test that.  Fingers crossed.Hank_______________________________________________
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