Caustic soda dip tank

davieh3350

Member
Location
Pitlochry
Today in my shed... I have been making a dip tank for cleaning off rust, paint, grease and dirt from bits of machines.
image.jpg
It's just an old oil tank with the top hacked off, the drain holes blocked off, the bracing inside removed and a rib fitted round to stop it bellying out. Nothing special...

This is a sewage pump that I had to repair.
image.jpg
The pump sat in a bucket of caustic soda/water mix for a few days, taken out and rinsed off, dried and then given a light wire brush, 10 seconds worth.
It eats grease, oil, paint, rust and dirt, skin and eyes, so you need to wear goggles and gloves and waterproofs and keep kids and animals well away. It doesn't touch iron based metal, but eats copper based alloys. Aluminium is not to go in at all, it dissolves quickly and it releases hydrogen gas which could go with a bang.

I've only started using it, played a little with the caustic/water ratio and heating it, but I think it's great stuff (again, treating it with respect)
Has anyone else used it?
 

burr elm

Member
Location
Bedfordshire
If you strip any wood such as doors you want plenty of vinegar or other mild acid to kill the caustic after you have washed it down with water.
 

davieh3350

Member
Location
Pitlochry
A bottle of vinegar sits beside the tank in case of it getting on the skin.

Never used it on wood, got to be pretty strong mix so that you're not soaking the wood for too long, it eats some of the old type glues, or so I've read.
 

davieh3350

Member
Location
Pitlochry
No a friend had a large tank that he used for stripping doors years ago.Tank was hot not warm, used to load tank overnight and power wash next morning.
I had a gas ring under a smaller tank, it was boiling, fairly moved the paint! think it's every ten degrees rise in temp halves the time it takes.
Do you know the ratio of caustic to water that he used?
 

burr elm

Member
Location
Bedfordshire
I would be inclined to say boiling is a bit ott when you think about what you are breathing in :nailbiting::nailbiting::nailbiting:.
Ratio of caustic/water i have no idea, water was very pale milky colour, however that could be down to paint particles.
 

davieh3350

Member
Location
Pitlochry
Think boiling was too hot, just by the amount of gas it used!
I think when you mix it at the start is when you need to watch for gas coming off.
I'm going to put 1000 litres in the tank along with 75 kg of caustic and see how that does for a start. Water in first though!
 

tinman

Member
Location
Ulster
would you not consider electrolysis a better and safer way to remove the rust.
i like to stay away as far as possible from anything acid like tbh.

mr rucker here explains it, all be it over a half hour but you can see the results.
 

davieh3350

Member
Location
Pitlochry
would you not consider electrolysis a better and safer way to remove the rust.
i like to stay away as far as possible from anything acid like tbh.

mr rucker here explains it, all be it over a half hour but you can see the results.
Looked a little at electrolysis, but going down this route as it's so simple, mix it up, put the bits in and walk away, the stuff I'm doing isn't needed ASAP. It doesn't eat away at the iron either, so if I left it for a month it wouldn't matter.
it's safe enough if you are careful, the strengths I was using doesn't lift your skin on contact.
Leaves the metal fairly rustproof for a fair while too.
 

tinman

Member
Location
Ulster
would it not eat away that strap?

long time ago since i was round the caustic baths, used to work in a factory where we dipped molds into a caustic bath and then a hot water bath to rinse it and then into a sand blaster for a clean, used it to remove rubber residue on injection molds.
 

davieh3350

Member
Location
Pitlochry
would it not eat away that strap?

long time ago since i was round the caustic baths, used to work in a factory where we dipped molds into a caustic bath and then a hot water bath to rinse it and then into a sand blaster for a clean, used it to remove rubber residue on injection molds.
No, doesn't eat away at them.

Pressure washer is fecked:(, it would just blow the stuff away without needing to scrub it, though at least scrubbing at it you notice little things that you wouldn't see 5 foot away.
 

laich

Member
You get it on ,Amazon or ebay. Or food wholesalers. Type in citric acid and it will come up. It is not expensive, I bought a 5 kg tub for about £20. It will remove rust from steel /iron , but will not remove paint or oil/grease.
 

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World Food Day: NFU Cymru celebrates Welsh food producers at the Senedd

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Written by Rachel Martin

NFU Cymru members and Assembly Members have been celebrating the role that Welsh farmers play in producing nutritious, high quality, safe affordable food during an event at the Senedd today on World Food Day (October 16).

The lunchtime event, which was sponsored by Llyr Gruffydd AM, included a special menu of fine Welsh produce.

Speaking at the event, NFU Cymru...
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