Having a blast

So, my friend Andy (the chap who gave me his old copper pipe – see A gift) has a hobbyist sandblaster in his garage and this got me thinking. How would freshly cast bronze clean up when subjected to the gritty blast of sand-laden compressed air?!

When I cast the bronze knife with James at Butser Ancient Farm, James had kindly given me a second unfinished knife for my son to work on. My son and I have started to clean this up but it is still far from finished.

Beer and Chinese take-away

I arranged to meet up with Andy at his house for a catch-up over a beer and Chinese take-away and asked if I could try out his sandblaster at the same time. He was happy for me to use the machine and even tried to sell it to me as he no longer had a need for it. I didn’t buy it but I took the unfinished knife to his house and expectantly tried it in the blaster.

The sandblaster itself was a simple cabinet containing the sand, the air-gun, and a pair of thick rubber gloved inserts into which one places their hands to work. The top was hinged and could be locked shut. Unfortunately, the seals on the lid were buggered and so much dust escaped that I had to keep stopping and going outside for fresh air. Cough!

Unexpected?!

It didn’t take long to blast clean a small area on the surface of the blade although the finish wasn’t what I expected. Having said that, I had never used a sandblaster before so I didn’t really know what to expect to be honest. The sand had nicely removed the oxidation from the surface of the metal but the more course texture remained. I think I was hoping it would have smoothed off the surface to at least a small degree. Maybe that was being overly optimistic.

I can see, for certain objects, the above texture may be a desired result as opposed to a polished finish, for example. However, the cast would need to be of significantly better quality.

When asked, Andy informed me that you could get different grades of sand for the blaster. The sand we used seemed very fine but he didn’t know what grade it was. I do wonder whether a more course grit would be capable of producing a smoother finish? Perhaps it would require a more powerful compressor too? Perhaps we’re getting into the realms of industrial strength sandblasters? I don’t know.

Either way, it was an interesting experiment.