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Re: welding plexiglass

Berney asked:

> I am making a plexiglass co2 reactor and need to know how the glue process is
> best accomplished. I need a good weld because it's under the tank and
> pressurized. The glue is water thin and a needle applicator is used for
> dispensing. I don't know if clamping is necessary, light pressure, or none is
> best. Anyone with experience or some idea how it is done?

I have an old plexi tank which required re-welding in one corner one
time, so I have some experience with it. The "glue" is not a glue at
all, but an acid which melts the two pieces together, hence "welds".
Both pieces need to be completely free of all dirt and especially oil
(skin oil). Both pieces where contact will be made need to be lightly
coated with the acid. Avoid overspilling, as this will discolour the
plexiglass, and avoid missing contact spots as this will not give an
airtight/watertight seal. Immediately place two pieces togther. Be
exact, you cannot move it afterwards. Put some pressure on the weld for
about 30 seconds (just by hand is sufficient). Plexiglass will re-harden
in about 15 seconds, so you have to move fast.

Sometimes using a small tray is good for getting even coverage of the
acid on the plexiglass. Pour acid in tray, dip edges where contact is
required into acid, place together. This wastes more acid, though.

If it is a corner weld, I like to run some of the acid along the corner
to ensure a better weld and a watertight seal. Test item for leakage. If
you have not achieved a water-tight seal, you can use silicon aquarium
sealant to do this job. First, though, you will need to lightly sand
over the weld to rough-up the plexiglass some. This will cloud the look
of the plexi, but give something for the sealant to grab onto.

Hope this helps!