Thinners eat tinplate!

[Yorkie]

For woodturning and other woodworking I often use sanding sealer. Sometimes I use shellac sanding sealer, other times - because it dries quicker - I use cellulose sanding sealer, which is rather thick so benefits from being thinned down a little - about 1/3 thinners. It's far cheaper to buy sealer and thinners in 5 Litre tins and I had a 5L tin of sealer and 5L tin of thinners in my garage, which I guess I've had for two years, and which were by now about half empty.

We've been away for a couple of weeks and when we returned I noticed ac strong smell of thinners in the garage. When I investigated, I discovered that the can of thinners had sprung many leaks from pinhole corrosion, so I decanted it into another container, and out of curiousity I slashed open the can to see the corrosion from the inside. I was astonished to see how bad it was and hadn't realised that thinners - or at least one of its constiuents, will attack metal so aggressively over time. I guess that most who buy 5L cans use it up far more quickly than I do, so in future, I'll buy smaller cans!

I've attached a couple of pics of the outside and inside of the can.

[Ian E G7OLT]

David,

Thinners are MEK i.e. Methyl Ethyl Ketone which absorbs moisture (hygroscopic). Once you've opened the can, the MEK absorbs moisture form the atmosphere and this is what is rusting the can from the inside.

Don't even think of emptying the contents into a plastic container. MEK dissolves polythene, polypropylene and even PVC, glass is the only safe container and even then you need to consider the material the stopper is made from.

Regards,

[Skywave]

A few years ago I opened a long-time stored plastic can of anti-freeze, only to find that it had polymerised the container and was useless! That particular A/F also contained MEK (so I was later told). I'm a bit more cautious of what A/F I buy these days, and try only to buy enough so that it is all used upon installation.

Al.

[Yorkie]

David,

Thinners are MEK i.e. Methyl Ethyl Ketone which absorbs moisture (hygroscopic). Once you've opened the can, the MEK absorbs moisture form the atmosphere and this is what is rusting the can from the inside.

Don't even think of emptying the contents into a plastic container. MEK dissolves polythene, polypropylene and even PVC, glass is the only safe container and even then you need to consider the material the stopper is made from.

Regards,

Thanks for reading my post Ian, and for your helpful comments.

Right, I'd better check the containers into which I decanted the thinners then! One was an aluminium water bottle, but with a plastic stopper, and although it hasn't dissolved, it's swollen, so clearly the thinners has reacted with it. It got me thinking about atitudes to the (un)safe handling of substances and times and events in my life long passed.

I started my career at the then 'Gas Board' in Nottingham as an apprentice in 1954 aged 15. At 17, having passed my intermediate City and Guilds exam, like other 'senior apprentices' I was given a kit of tools and put to work alone. Invariably, we were given the less pleasant jobs, one of which was de-scaling 'Stotts' tea boilers (the big chrome things that are long since obsolete) in canteens and restaurants. Due to it being a hard water area, the boilers scaled up every three months or so, and de-scaling them involved dismantling the boiler and pouring hydrochloric acid all over the internal components of the boiler, which then started fizzing and giving off acrid fumes as the acid dissolved the lime-scale. Then the components were rinsed, and the boiler reassembled.

For transport, we got around on the local bus service and carried the concentrated acid is a glass demijohn, along with a toolbag slung over the shoulder with a hammer shaft through the handle to carry it with, with the demijohn held on a finger through the glass 'ear' of the bottle. It's hard to believe that there was ever a time when one would be allowed to hop on a bus with a gallon of highly corrosive acid! No markings on the container, no protective clothing - no worries!

The other unplesant task at aged just 17 was attending sucides when people put their heads in the gas oven. All that was needed was to test the installation to ensure that there were no gas leaks, and to confirm that the oven wasn't defective - a simple enough task, but the deceased person was there while you were going about it. You then had to attend the inquest on the lost soul, which was all very matter of fact - a little thing in a busy day along with other jobs. Just turned up in your overalls, left your toolbag in the cloak-room, told the coroner that there were do defects in the installation or cooker, and 15 mins later, you were on your way to get on with the rest of the days work. Life was cheap, and there was little sympathy for the deceased.

How times change - when I look back at some of the working practices -working unsurpervised at 17 on live (highly toxic) coal gas inside buidings such as factories and offices, where it was normal practice to saw through the main incoming service pipe and plug it with a large ball of 'Denso' (fibreglass cloth with a gooey substance on it), it's a miracle that there weren't many fatialties or serious incidents.

It's long since been against the law to do things like that, but the approach back then wasn't: 'is this a safe working practice and if not, how can it be made safer?', but: 'this is very dangerous, so take care or you might kill yourself or someone else, which would be a very careless and stupid thing to do'.

A considerable digression from rotting thinners cans, but I hope it's of interest.

[Joe]

It's long since been against the law to do things like that, but the approach back then wasn't: 'is this a safe working practice and if not, how can it be made safer?', but: 'this is very dangerous, so take care or you might kill yourself or someone else, which would be a very careless and stupid thing to do'.

I subscribe to the latter view and think that when you're doing something you know is dangerous you take far more care so end up being safer.

- Joe

[Paula A]

I love to give people a little lecture on the dangers of electricity when somebody comes along and says "12V is totally safe" .. If they have ever had a belt from a huge bank of 12V batteries (emergency lighting and alarms in a huge college damp basement.. standing in about an inch of water) due to damp hands and leaky boots on a wet floor they wouldn't be quite so sure..

My scariest moment must have been bashing back in the 3 "repaired" fuses on a 3 phase board while standing on an old pub table top which was sitting in a large puddle.. big lumps of wood come in very handy at times... It's a matter of knowing the danger and taking sensible precautions... and yes.. I have a matching pair of burn scars from brushing against an ungrounded lighting rig many years ago with a nicely grounded microphone stand in my other hand... 440v hurts when you wake up a few hours later !!