Message-ID: <3B09E91A.F5B2D3B8@bellsouth.net> From: John De Armond Newsgroups: rec.crafts.glass Subject: Re: UV-set glue cure, how? Date: Tue, 22 May 2001 00:20:42 -0400 Bathsheba Grossman wrote: > > Hi, I've been trying to make some glass sculptures by gluing up pieces > with UV-set glue (they look like http://www.bathsheba.com/bluestar.gif) > and I'm just going nuts trying to find a reliable way to cure the glue. > > For a while I worked with Loctite Impruv, and in the summer I was able to > cure it by leaving it in sunlight for 1/2 hour to 1 hour. This works, but > it makes an awfully slow pace for a piece that has 24 or 48 glue joints. > And in the rainy season here it gets very hazy, and the sunlight is no > longer intense enough to do the job. Here's a note I sent to someone via private email the last time this issue came up: ---------- >What type of u.v. glue are you using?, it should not > > yellow. I'm working on some new proposals for laminated glass fountains for > > new art museum in Nashville, so I've been looking into u.v. adhesives > > further. have always used Loktite or Dymaxbut just got in samples from a > > company called Tangent. I do a little fusing and slumping as well . I think the Loctite UV adhesive really sux. My favorite is Norland (http://www.norlandprod.com/adhesives.html). Loctite is a UV-activated adhesive where the UV activates a hardening agent already built in. Norland is a UV-catalyzed adhesive where the UV actually catalyzes the hardening process. There are many differences. First, the Norlan adhesive can be precured or "flashed" with UV before assembly. Just enough UV to cause the stuff to gel. After assembly, just a little more UV sets it. Very nice when you have to hand-hold the piece until curing. The Loctite stuff, on the other hand, doesn't start hardening until the UV flips the catalysts' "switch" and then it cures independent of UV intensity. With a strong UV source, you can feel the Norland stuff "bite". And with the loctite, oxygen inhibits the activation of the catalyst so the surface never quite cures, as you've probably noticed. The surfaces exposed to air remain tacky. Finally, the Loctite takes an order of magnitude more UV than the Norland. A black light will cure Norland. A high intensity UV lamp (made by removing the arc tube from a mercury vapor lamp and mounting it in a reflector) will cure the Norland practically instantly. It's just barely enough to do the Loctite. Finally, the Norland is cheaper! --------- My high intensity UV light that I mentioned is made from a 175 watt mercury vapor security light and a 500 watt halogen light fixture. I stripped the ballast out of the security light and mounted it in a paint can that I filled with transformer oil (the ballast gets very hot in this service). I took the mercury vapor bulb and cut the outer glass envelope off so I could gain access to the inner arc tube. I then took a 500 watt quartz-halogen light fixture and gutted it of everything except the reflector. I mounted the arc tube from the mercury vapor light in the focus of the fixture in place of the quartz-halogen lamp. I wired the lamp to the ballast. I left the glass cover off, as it blocks UV light. That's all there is to it. This lamp will cure Norland in seconds even though Norland is primarily a long wave cured adhesive. It will actually cure Loctite Impruv in a reasonable amount of time. Caution is required with this lamp, as it produces enough UV light to damage your eyes in seconds. It will also burn the skin in minutes. It takes several minutes for the lamp to warm up after being turned on. During that period and when I'm not actually curing adhesive, I keep the lamp face-down against some refractory that absorbs the UV. I also wear safety glasses with a good UV coating on them to take care of stray beams or reflections. Finally, this light will fairly quickly bleach out the dye in your clothes so either don't wear good clothes when using it or don't allow the UV light to fall on your clothes. The mercury arc tube normally operates in an insulating vacuum. Operated in open air, it draws more current which will cause the ballast to overheat. That is why I operate the ballast in transformer oil inside the paint can. If you can't find transformer oil, ordinary medical mineral oil works fine. You can get it by the gallon at the farm supply store. If you think you might actually build a lamp like mine, drop me a note and I'll take some photos for you. John From: John De Armond Subject: Re: Finding the tinned side of float glass Date: 2000/08/08 Message-ID: <39906582.9EFA8B94@bellsouth.net> Newsgroups: rec.crafts.glass Crystal Images wrote: > > Interesting. I didn't know about the different curing characteristics. Which > Norland formula are you using? I use #68, which tacks in about 20 seconds, > allowing me to hold the pieces with my hands until they "grab". I also like > it that excess is easy to peal off before the cure is full. One of the things > I like about it's not being anaerobic. How long does Loctite take to cure? I've been using the Norland 60. The #68 looks interesting too. To tell the truth, I didn't realize they made so many adhesives. #60 is is very rigid once cured and bonds to the glass so tightly that sometimes it will chip the glass like hide glue when broken apart. I'm not sure how long Loctite takes but it's awhile. hand-holding really isn't practical. Especially since it takes a huge dose of shortwave UV to trigger it. IF you look on Noreland's data sheet on #60 here: http://www.norlandprod.com/adhesives/noa60.html, you'll see a mention of "oxygen inhibition". This is a real problem with the loctite adhesives. What happens is oxygen in the air inhibits the curing of the adhesive wherever it is exposed to air. The surface remains tacky regardless of how much UV is applied. Aside from being annoying, it leaves a dull surface. John |
