<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style=""><span style="font-size: 13px;">Hi Alan,</span><div style="color: rgb(0, 0, 0); font-family: arial, sans-serif; font-size: 13px;"><br></div><div style="color: rgb(0, 0, 0); font-family: arial, sans-serif; font-size: 13px;">I wasn't sure what Marine epoxy is (I think it's more of a branding/marketing thing), so I looked up the spec sheet on one at homedepot:</div><div style=""><span style="font-size: 13px;">https://www.homedepot.com/catalog/pdfImages/29/29ce3d40-ccc6-44ba-a262-2bb651511fea.pdf</span></div><div style=""><span style="font-size: 13px;"><br></span></div><div style=""><span style="font-size: 13px;">Seems it's Silica/quartz (60%) mixed with Aliphatic epoxy (30%) and some other things. Looking up water absorption data on Aliphatic epoxy as found:</span></div><div style=""><span style="font-size: 13px;">http://cdmf.org.br/wp-content/uploads/2017/03/mechanical-properties-water-absorption-and-adhesive-properties-of-diepoxy-aliphatic-diluent-modified-dgebacycloaliphatic-amine-networks-on-316-l-stainless-steel.pdf</span></div><div style=""><span style="font-size: 13px;"><br></span></div><div style=""><span style="font-size: 13px;">Fig 4 implies a 1.5% to 2% water absorption depending on the type of Aliphatic epoxy.</span></div><div style=""><span style="font-size: 13px;"><br></span></div><div style=""><span style="font-size: 13px;">Of course, this doesn't necessarily mean something is bad for use in Marine applications. I'm not sure that water absorption factors mean something is more/less hydrophobic/hygroscopic either.</span></div><div style=""><span style="font-size: 13px;"><br></span></div><div style=""><span style="font-size: 13px;">The Wikipedia epoxy entry for those that care (there is a water soluble epoxy too!): </span><br>https://en.wikipedia.org/wiki/Epoxy</div><div style=""><br></div><div style="">On the topic of water absorption, some concretes, IIRC, can absorb 9% of their weight in water. If you're building a large concrete submarine, you need to take that into account. :) Would be rather problematic to find your submarine suddenly weighing 10+ tonnes more than planned!</div><div style=""><br></div><div style="">Cheers,</div><div style=""> Ian. </div><div style=""><br><blockquote style="color: black; font-family: arial, sans-serif; font-size: 10pt; padding-left: 5px; margin-left: 0px; border-left: 2px solid rgb(0, 0, 255); font-weight: normal; font-style: normal; text-decoration: none;">-----Original Message-----
<br>From: Alan via Personal_Submersibles <personal_submersibles@psubs.org>
<br>Sent: May 9, 2018 4:20 PM
<br>To: Personal Submersibles General Discussion <personal_submersibles@psubs.org>
<br>Subject: Re: [PSUBS-MAILIST] material question
<br><br><zzzhtml><zzzhead><zzzmeta http-equiv="content-type" content="text/html; charset=utf-8"></zzzmeta></zzzhead><zzzbody dir="auto"><div>Hi Ian,</div><div id="AppleMailSignature">a while since I looked at fibreglass, but I made my ambient from epoxy</div><div id="AppleMailSignature">rather than polyester because it was less hydroscopic apart from other</div><div id="AppleMailSignature">things. I used a marine epoxy, so I guess there are differing levels of</div><div id="AppleMailSignature">water resistance within the epoxy products.</div><div id="AppleMailSignature">Alan</div><div id="AppleMailSignature"><br>Sent from my iPad</div><div><br>On 10/05/2018, at 11:00 AM, irox via Personal_Submersibles <<a target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br><br></div><blockquote type="cite"><div><div style="font-size: 13px;color: rgb(0, 0, 0);font-family: arial,sans-serif;"><style type="text/css"><ZZZ!-- DIV {margin:0px;} --></style><div style="font-size: 13px;color: rgb(0, 0, 0);font-family: arial,sans-serif;">What Sean said. Look up the spec sheets and you should get the water absorption rates and equilibrium.<br><br>Alan, I don't know much about GRP boat building (a little about surfboards), but it seems traditional to use polyester resin for this types of work. Polyester is fairly low water absorbing, around 0.55%: <br><a target="_blank" href="http://www.ndt.net/article/ndt-slovenia2013/papers/189.pdf">http://www.ndt.net/article/ndt-slovenia2013/papers/189.pdf</a><br><br>For comparison, some types of Nylon can absorb 3.5% mass in water (some are lower).<br><br>This 2009 paper on "Interaction of Water with Epoxy" indicates there is some swelling with epoxy:<br><a target="_blank" href="http://prod.sandia.gov/techlib/access-control.cgi/2009/094405.pdf">http://prod.sandia.gov/techlib/access-control.cgi/2009/094405.pdf</a><br><br>There a few different types of epoxy, I randomly picked "novolac epoxy" from the epoxy family, and found:<br><a target="_blank" href="https://hal.archives-ouvertes.fr/jpa-00251480/document">https://hal.archives-ouvertes.fr/jpa-00251480/document</a><br>After 10 days a 2.3% mass increase was observed.<br><br>Disclaimer: I didn't full read all publications I've linked to.<br><br>Cheers,<br> Ian.<br><br><br><blockquote style="padding-left: 5px; margin-left: 0px; border-left: #0000ff 2px solid; font-weight: normal; font-style: normal; text-decoration: none; font-size: 10pt; font-family: arial,sans-serif; color: black;">-----Original Message-----
<br>From: Alan via Personal_Submersibles <personal_submersibles@psubs.org>
<br>Sent: May 9, 2018 2:39 PM
<br>To: Personal Submersibles General Discussion <personal_submersibles@psubs.org>
<br>Subject: Re: [PSUBS-MAILIST] material question
<br><br><zzzhtml><zzzhead><zzzmeta http-equiv="content-type" content="text/html; charset=utf-8"></zzzmeta></zzzhead><zzzbody dir="auto"><div>Hi Emile,</div><div id="AppleMailSignature">my brother-in-laws fibreglass yacht has been sitting in the harbour</div><div id="AppleMailSignature">for at least 30 years, so pretty impervious to water.</div><div id="AppleMailSignature">The glass in the fibre would not crush, but the resin around it would squash</div><div id="AppleMailSignature">a little under that pressure. I would think the resin would seal any exposed </div><div id="AppleMailSignature">fibres by squashing around them when put under that kind of pressure.<br>What are you sending down that deep?</div><div id="AppleMailSignature">Alan<br>Sent from my iPad</div><div><br>On 10/05/2018, at 5:34 AM, emile via Personal_Submersibles <<a target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br><br></div><blockquote type="cite"><div><zzzmeta http-equiv="Content-Type" content="text/html; charset=us-ascii"><zzzmeta name="Generator" content="Microsoft Word 12 (filtered medium)"><style><ZZZ!--
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</o:idmap></o:shapelayout></xml><zzz![endif]--><div class="WordSection1"><p class="MsoNormal"><span style="font-family:"Arial","sans-serif"">Hi All, <o:p></o:p></span></p><p class="MsoNormal"><span style="font-family:"Arial","sans-serif""><o:p> </o:p></span></p><p class="MsoNormal"><span style="font-family:"Arial","sans-serif"">Material question:<o:p></o:p></span></p><p class="MsoNormal"><span style="font-family:"Arial","sans-serif"" lang="EN-US">Can prefabricated epoxy/glassfibre plate material (like PCB) withstand 5000M / 18.000Ft presurised water? <o:p></o:p></span></p><p class="MsoNormal"><span style="font-family:"Arial","sans-serif"" lang="EN-US">Or will it be impregnated after a while?<o:p></o:p></span></p><p class="MsoNormal"><span style="font-family:"Arial","sans-serif"" lang="EN-US"><o:p> </o:p></span></p><p class="MsoNormal"><span style="font-family:"Arial","sans-serif"" lang="EN-US">Thanks in advance<o:p></o:p></span></p><p class="MsoNormal"><span style="font-family:"Arial","sans-serif"" lang="EN-US"><o:p> </o:p></span></p><p class="MsoNormal"><span style="font-family:"Arial","sans-serif"">met vriendelijke groet, with best regards<o:p></o:p></span></p><p class="MsoNormal"><span style="font-family:"Arial","sans-serif""><o:p> </o:p></span></p><p class="MsoNormal"><span style="font-family:"Arial","sans-serif"">Emile D.L. van Essen<o:p></o:p></span></p><p class="MsoNormal"><o:p> </o:p></p></div></zzz![endif]--></zzz!--[if></zzz![endif]--></zzz!--[if></zzzmeta></zzzmeta></div></blockquote><blockquote type="cite"><div><span>_______________________________________________</span><br><span>Personal_Submersibles mailing list</span><br><span><a target="_blank" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a></span><br><span><a target="_blank" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a></span><br></div></blockquote></zzzbody></zzzhtml></personal_submersibles@psubs.org></personal_submersibles@psubs.org></blockquote></div></div>
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