Making aerosols work better

Underseal
Originally uploaded by Phil_Parker.

Someone clever once said, "Eat a live frog before breakfast and nothing worse will happen to you all day ". I've been staring at a frog for a couple of weeks and finally got around to chomping on it yesterday.

My frog appeared when I crawled under the camper van to try and work out why the heating was even more pathetic than normal. Nothing obvious appeared at the time but I did spot that sometime in the past I've scraped the bottom of the vehicle. Some dented tinware was quickly flattened but the damaged underseal couldn't be fixed at the time as I'd run out.

To buy time I sprayed some normal Waxoyl under there. That's OK for a while but I didn't fancy it's chances with all the water on the roads at present. That water contains road salt or VeeDub killer as it's better known for the ability it has to promote rust. A new can of spray underseal was acquired and has sat in the garage taunting me for a week. A cold and wet week. The sort of week that makes you want plenty of protection on the bottom of a car and yet provides no incentive to crawl around underneath one. And yes I know this sort of job should be done in the summer thank you very much.

With reasonable weather and a conscience biting at me I slipped out to wire brush the affected area (the rear cross member) and give it a shot of Eastwood Rust Encapsulator. This came out very well in a recent rust stopping test in one of the classic car mags so I thought it was a worthwhile thing to do. My plan was to top it off with underseal to protect against flying stones.

So there I am lying on my back under the van having given the spray can a shake for the regulation two minutes, pressed the nozzle. Nothing. Well, not quite nothing but a pathetic excuse for a spray. Another shake and no real improvement. And I really didn't fancy using the brushable stuff for such a small job - it's horribly messy. Forget to wear a big rubber hazardous chemicals protection suit and you'll be washing it off for days in my experience...

My suspicion was that the viscous liquid in the can had solidified while sat in the cold garage. When shaking it I couldn't hear the ball bearing in the can (has anyone ever seen one of these ?) that I assumed would be in there. Perhaps all it needed was warming up ?

With the house empty I made a bath in the sink for the can with lovely hot water from the tap and a bit from the kettle. 15 minutes or so later the can was warm and the ball bearing could be heard on shaking. Best of all the black stuff sprayed out beautifully.