Window repair with Tupperware, Silica Gel and an Aquarium pump...

A while ago, the Ivy that was growing on the wall of my garage/workshop found its way through the seal on a double-glazed window unit, causing condensation to form inside. About a quarter of an inch of water had also accumulated in the bottom between the panes.
Removing the window to open, dry and reseal would have been a real pain, and replacement would be expensive as it was laminated glass, so I thought about how to extract the water in-situ.
I managed to drill a 1.5mm hole in the bottom-left glass using a carbide PCB drill bit (well several actually..!), and drained out the pool in the bottom, but the condensation remained, with no change for over a year.

I realised that what it needed was some airflow through the space between the panes, and actively extracting the moisture from the circulating air. I drilled a second hole in the opposite corner of the glass, and attatched some polythene windscreen-washer tubing to both holes, using the ends of a couple of syringes glued on with silicone sealer. I was expecting to have to leave it going for a long time (maybe weeks) so I stapled the tubing to a wood block screwed into the frame (right).

I found some bags of silica gel I had lying around.  Silica gel is highly moisture-absorbent, and commonly used in various packaging applications. The stuff I had was pretty old, and so needed  reactivating  by baking in an improvised oven at about 100 deg.C for 24 hours. This turned it from milky pink to a deep blue colour.

The silica gel was then placed inside a Tupperware food container, along with an aquarium air pump. This provided a sealed drying system, which would circulate the air through the window and the silica gel. The pump inlet wasn't very amenable to attatching a tube, so it was easiest to just put it inside the container. The heat from the pump might also help things along.

(The picture on the right was taken after it had been running for a few hours  - the  silica gel near where the inlet tube came in had turned white, showing that moisture had been absorbed.)

I left this running, expecting to not notice anything for a while, however after only 6 hours, the condensation patch had become very noticeably smaller. If I'd known it would be this quick I'd have set up a camera to do a time-lapse sequence..!

By 9 hours, all the condensation had gone. The only visible remains were some very slight marks where the droplets had been.

After the ivy was removed, I used a syringe to inject some conformal coating under the rubber seal on the outside - hopefully this is runny enough to soak into the remnants of ivy and flexible to remain sealed - time will tell, but at least I now know I can recover it if it does get damp inside again!