I am building a stitch and glue boat these days. I have gotten to the point where I am fiberglassing the hull. The epoxy (West Systems) is not behaving the way I remember it during the warmer months. It is much more viscous when I'm mixing it. It gets really white. I thought that since the temperature is less, the pot time would be noticeably longer. It is not. Furthermore, it doesn't take long before it starts turning my boat milky white with each stroke of my foam brush. Does anybody know what is causing this? Is there a better epoxy system to be using? Also, I'm seeing an oily film on the epoxied surface 24 hours after it has set up. I am assuming this is the dreaded "amine blush". I have not seen this phenomenon before. I used a scratch pad and water to get it off. That seemed to work. Some kit companies say you don't have to sand between coats if you don't wait longer than 2 or 3 days. Is this accepted practice? Does it apply in all temperature and humidity conditions? Does West Systems have a web site? *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net ***************************************************************************
Keith Kaste wrote: > > I am building a stitch and glue boat these days. I have gotten to the > point where I am fiberglassing the hull. The epoxy (West Systems) is > not behaving the way I remember it during the warmer months. It is much > more viscous when I'm mixing it. It gets really white. I thought that > since the temperature is less, the pot time would be noticeably longer. > It is not. Furthermore, it doesn't take long before it starts turning > my boat milky white with each stroke of my foam brush. Does anybody > know what is causing this? Is there a better epoxy system to be using? The clues you give suggest that the epoxy has "separated" slightly, owing to long storAge at a low temperature. If the containers are reasonably transparent, examine both hardener and resin with a strong light behind the containers and see if you can spot any separation. A flashlight down the throat if you have an opaque container may do the job, also. If it has separated, incubate it for several hours in warm water (100F), stirring occasionally. It will remain well-mixed for quite a while unless you let it get very cold again. The best solution is to keep both hardener and resin in a heated plywood box. I used a 75 W light bulb to keep such a box warm and it worked well. For reference: I found 80 - 90 F was ideal for System 3 resin/hardener (I used 2:1::normal:fast, though fast hardener is OK to store at that temperature). YMMV > Also, I'm seeing an oily film on the epoxied surface 24 hours after it > has set up. I am assuming this is the dreaded "amine blush". I have > not seen this phenomenon before. I used a scratch pad and water to get > it off. That seemed to work. Some kit companies say you don't have to > sand between coats if you don't wait longer than 2 or 3 days. Is this > accepted practice? Does it apply in all temperature and humidity > conditions? If the blush does not disappear on clearing up the separation problem, something else is wrong. Check your mixing devices. Small volumes are notoriously difficult to measure accurately, especially if the epoxy ingreds are cool -- they stick to the container walls badly. Switch to weighing the ingreds into a single container: resin, then hardener. Very easy to control the mix that way. P.S. Keith, it may be uncool to double post to both Paddlewise and to Wave~Length. I suspect we should ask Jackie and Howie (thank you Alan) about that. Different, identical posts are probably OK, if I understand the etiquette properly. -- Dave Kruger Astoria, OR sea kayaker -- and chemist *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net ***************************************************************************
Keith Kaste wrote: > > The epoxy (West Systems) is > not behaving the way I remember it during the warmer months. It is much > more viscous when I'm mixing it. It gets really white. I thought that > since the temperature is less, the pot time would be noticeably longer. > It is not. Forgot to comment on this. The high viscosity is a sure sign of cold epoxy. The high viscosity makes mixing tough, and "whips" air into the mix. Even though the resin is cold to begin with, the exothermic behavior of the mix will quickly heat it up, foaming the bubbles and creating a hell of a mess! Probably the white appearance is due to bubbles in the resin or maybe "outgassing" from the wood. Hard to tell without more info. -- Dave Kruger Astoria, OR *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net ***************************************************************************
I agree with Dave Kruger's "whipped in air" diagnosis. The high viscosity resin is trapping air. Warming up the resin before mixing will reduce this problem, but when it cools off again as you start spreading it on the fiberglass, you will again force air into the resin again, making it turn white. The oily film is probably amine blush as you say. If you can heat your space up, you will probably have better results. However, you want to do your glassing on falling temperatures so the any trapped air shrinks instead of expanding. So heat up the space hot before starting and let it cool down slowly as you work. Note that a kerosene or propane heater produces water vapor as a result of combustion and humidity exaserbates blushing problems. I have had very good results with MAS epoxy. It is low viscosity and does not blush. They now have "winter cure" which cures down to 35°. It stays low viscosity and does not crystalize at low temperatures. NOTE: where I work is a distributer for MAS so I am not completely unbiased, but I used it before I started working there. Nick At 4:03 PM -0800 2/1/98, Keith Kaste wrote: >I am building a stitch and glue boat these days. I have gotten to the >point where I am fiberglassing the hull. The epoxy (West Systems) is >not behaving the way I remember it during the warmer months. It is much >more viscous when I'm mixing it. It gets really white. I thought that >since the temperature is less, the pot time would be noticeably longer. >It is not. Furthermore, it doesn't take long before it starts turning >my boat milky white with each stroke of my foam brush. Does anybody >know what is causing this? Is there a better epoxy system to be using? > >Also, I'm seeing an oily film on the epoxied surface 24 hours after it >has set up. I am assuming this is the dreaded "amine blush". I have >not seen this phenomenon before. I used a scratch pad and water to get >it off. That seemed to work. Some kit companies say you don't have to >sand between coats if you don't wait longer than 2 or 3 days. Is this >accepted practice? Does it apply in all temperature and humidity >conditions? > >Does West Systems have a web site? > > > >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >Wave~Length Paddling Mailing List >Submissions: wavelength_at_lists.intelenet.net >Subscriptions: wavelength-request_at_lists.intelenet.net >World Wide Web: http://www.wie.com/~wavenet/ >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Nick Schade Guillemot Kayaks c/o Newfound Woodworks, RFD 2 Box 850, Bristol, NH 03222 (603) 744-6872 Schade_at_guillemot-kayaks.com http://www.guillemot-kayaks.com/ >>>>"It's not just Art, It's a Craft!"<<<< *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net ***************************************************************************
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