Epoxy system preferences?
Printed From: Yachts and Yachting Online
Category: General
Forum Name: Repair & maintenance
Forum Discription: Questions & tips on the subject
URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=11428
Printed Date: 14 May 25 at 1:38am
Software Version: Web Wiz Forums 9.665y - http://www.webwizforums.com
Topic: Epoxy system preferences?
Posted By: ChrisB14
Subject: Epoxy system preferences?
Date Posted: 08 Apr 14 at 6:01pm
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This must have been discussed before, but I can't find a thread on it both here and at www.boatdesign.net. So I thought I would ask: Which epoxy (systems) do you guys prefer? The background: I am starting on a "stitch and glue" build (a Farr 3.7) and looking around for a good solution. The two main options appear to be SP 106 and West 205 (with slow and fast hardeners depending on the exact task). In the past I have used SP 106 for GRP and carbon repair work and was happy with that. Of course reading the Gougeon Brother's book one is left with the impression that the boat will fall apart, you will develop boils on your hands and ultimately die if you don't use the West System  .Any strong opinions? Alternative suggestions? Does it even matter? Thanks for any comments, Chris ------------- B14 GBR 748 Bullet B In build: Farr 3.7 GBR 410 (both sail number and the current number of loose parts) |
Replies:
Posted By: Rupert
Date Posted: 08 Apr 14 at 6:57pm
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Ed Bremner on the cvrda site always suggests that speaking to Matrix Mouldings (www.matrix-composites.co.uk) is a good idea. ------------- Firefly 2324, Puffin 229, Minisail 3446 Mirror 70686 |
Posted By: JimC
Date Posted: 08 Apr 14 at 7:10pm
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As I recall West is mix by weight and SP is mix by volume. That in itself is probably enough to give most people a preference for one or the other. And yes, there are others which have a good rep. Sicomin being the most obvious example. Frankly at our amateur level there probably isn't much to choose between Sp/Gurit, West and Sicomin products.
I normally use SP because I like to mix by volume, but if I were local to Bristol I would be strongly tempted to use Matrix and Sicomin simply because Wiz at Sicomin has an ear that is well worth bending. |
Posted By: Oatsandbeans
Date Posted: 08 Apr 14 at 7:52pm
| SP106 and WEST 105 with their associated hardeners are now very similar. The SP 106 used to be a bit better in the extreme cold because when you mixed it, it generated a kick on mixing, that helped push the cure through, but they ditched that because it wasn't so good on colour so there is not much in it. Both systems are fine for wood epoxy and general repair work. The most important thing with these epoxy systems is getting the ratio right as they have low hardener addition rates which are sensitive to getting it right, and if you over, or under do, the hardener the properties are awful. |
Posted By: craiggo
Date Posted: 08 Apr 14 at 8:27pm
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I've used West by volume and by weight with no difference in terms of the results. The biggest issue is always amine blush but if using it as an adhesive with low density filler this doesn't usually present a problem. If you do use West, I'd recommend using 207 hardener (for clear coating). Once you've cut all your panels out, roller it on all surfaces. The only bit of the West system I've been disappointed with is the filleting blend which used to give a nice orange wood colour but now seems a bit beige.
In the Grad fleet they were quick to make use of West in the mid 80s and these have proven to be some of the most robust long lived competitive boats in the fleet. I have used Sicomin resins when we built the C-class Invictus, but this was exclusively with Carbon rather than wood!!!!! Found it to mix out well and cure consistently. Wiz is always full of good advice and will make sure you get the right stuff, but I found it a bit pricey. I've never used SP so can't comment on it. |
Posted By: I luv Wight
Date Posted: 08 Apr 14 at 10:18pm
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I like Sicomin SR8500 ( from Matrix ) for vaccing hulls and foils, and general purpose SP320 for bonding, filling and coating. I have tried many different other ones, but there's always seems to be some problem - crystallization, too sticky, too brittle with an overnight cure, too fast, too slow, too brown, too shrinky as a coating, goes off, doesn't like damp or cold, too sticky residue on the cured resin, too bendy when cured ( SP Speedipack!), too smelly. Measure with kitchen scales! ------------- " rel="nofollow - http://www.bloodaxeboats.co.uk" rel="nofollow - http://www.bloodaxeboats.co.uk Andy P foiling Int Moth GBR3467 Freedom 21 Codling |
Posted By: ChrisB14
Date Posted: 09 Apr 14 at 4:04pm
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Lot's of very useful comments and advice, thanks! The brief response is that I guess I will be contacting Matrix for detailed advice and materials for our build. From what I can see West 105, SP 106 and Sicomin SR 5550 are all roughly the same price (if anything Sicomin a tad cheaper), with substantial variations depending on where you buy. SP 320 is a major step up in price, though. Andy: Is it simply that 320 is clearer than 106, or are there other benefits? Let me see if I got this right: a resin system requiring 3:1 is less sensitive to small measurements errors than a 5:1 system? I assume that's because for a given error the relative effect is smaller? It also appears that all three (Gurit, West, Sicomin) now specify both weight and volume ratios. I have found that people tend to hold deep convictions about which is the more reliable way to go. Off the top of my head, I would prefer volume (using syringes) for small amounts and weight for larger amounts. But maybe weight is the best way to go in any case. Thanks again! Chris ------------- B14 GBR 748 Bullet B In build: Farr 3.7 GBR 410 (both sail number and the current number of loose parts) |
Posted By: alstorer
Date Posted: 09 Apr 14 at 4:46pm
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which is more reliable is purely down to your measurement systems. Really clever formulation can be done that makes the two ratios the same... ------------- -_ Al |
Posted By: Oatsandbeans
Date Posted: 09 Apr 14 at 6:15pm
| 320 is not just clearer 106 -it is a completely different animal. 320 is generally a higher spec system. I would go for what Andy says, he knows, as he has worked with most of the systems (- I just formulated them.) |
Posted By: Reuben T
Date Posted: 09 Apr 14 at 7:22pm
| the pumps that can be bought with West are really useful and mean that you can get the perfect ratio every time without gaffing around with measuring/weighing(very good in a panicky situation with curing epoxy). |
Posted By: I luv Wight
Date Posted: 09 Apr 14 at 8:39pm
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I do umpteen mixes in a week, and it's very very rare to get a soft cure - weighing - kitchen scales are good for mixes 30g - 2 kg. Pumps get gunked up, and don't measure accurately , so i use the big pumps for R and H just to get it out of the containers, but weigh everything. e g for 320 - weigh resin , subtract 8g cup weight, times 4, divide by three, add 8g = weight target with hardener. I always have several kg of either resin or hardener left when it's time to buy more, so it's good to keep with the same system! I think west 105, SP106, sicomin 5500 are very similar. SP 320 is a bit thinner and flows better, maybe better properties. Fast cure even with slow H. Sicomin SR8500 is thicker but is good when vaccing, fast H is relatively slow, and has good performance when cured at ~ 60°C ------------- " rel="nofollow - http://www.bloodaxeboats.co.uk" rel="nofollow - http://www.bloodaxeboats.co.uk Andy P foiling Int Moth GBR3467 Freedom 21 Codling |
Posted By: alstorer
Date Posted: 09 Apr 14 at 9:46pm
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Looking up the MSDS , I see 320 has a Bis F epoxy component (can't hide everything in the formulation!) which would, to a certain extent, explain the higher performance and cost. ------------- -_ Al |
Posted By: Oatsandbeans
Date Posted: 10 Apr 14 at 5:29pm
| Yes its a real sod that you have to put all that stuff in the msds - it makes it easy for others to pick apart your systems without them even having to do any real chemistry,( like sticking it through the gc or ftir,) but then I have got quite a bit over the years from the msds 's of others, even though sometimes you suspect that they have the odd porkies in them! |
Posted By: ChrisB14
Date Posted: 14 Apr 14 at 5:24pm
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Thanks for the tip Al: I have started looking over the MSDS to get a better idea of the different epoxy systems (of course following some background reading on the different components). A fourth option I have come across is Mas Epoxy. Given the 2:1 mixing ratio I would suspect they are straightforward to use. Yet, they have not been mentioned in this thread.
That would also suggest it has a fairly short pot life even with a slow hardener? Or is it really just the final cure that is fast (I would expect the two to be linked)? Thanks for the patience with my newbie questions! ------------- B14 GBR 748 Bullet B In build: Farr 3.7 GBR 410 (both sail number and the current number of loose parts) |