From: John De Armond
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.
From: John De Armond
Subject: Re: Finding the tinned side of float 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.