Thread: Good trick to strip paint

Rob where you say you did the first bit with washing soda and the battery charger excuse my ignorance but how does that work?

thanks, Sean

Hi Sean,

There was quite a big thread on this back aways, but basically you:

- put your metal parts in a plastic tub
- attach the negative lead from a battery charger to them
- put a piece of junk steel (old tin sheeting works best) in the bucket, away from the parts so they don't touch
- attach the positive lead to that
- put water in bucket to cover parts to be stripped/cleaned
- turn on battery charger
- add washing soda (from supermarket laundry section) until the amps on the battery charger come up a bit
- leave for 24 - 48 hours
- remove and clean up on wire buff etc.

That's it.

If the part stops gassing, remove the tin sheeting and clean up a bit, put back.

I like this method because it's quite safe, and you can set it up and get it going/done quickly.


Rob

Thanks Rob great summary - one question if I may - do you put the junk metal in the basin and solution as well?

ta Sean

Originally Posted by seanlark

Thanks Rob great summary - one question if I may - do you put the junk metal in the basin and solution as well?

ta Sean

Yes.

The way it works is that the washing soda in the water acts as a conductor.

The current flows (neg to positive) and in doing so, lifts the paint/rust and carries it towards the scrap steel.

When it's working the part to be cleaned will gas vigorously and foam tends to form on the water surface.

I leave the charger on overnight and next day it's generally stripped enough that the paint/sludge left can be washed off. Using a pressure washer makes this an easy and less messy operation. Gets into all the nooks and crannies.

You can only use this method with steel and cast iron.

Rob

Originally Posted by seanlark

Rob where you say you did the first bit with washing soda and the battery charger excuse my ignorance but how does that work?

thanks, Sean

The process is called "electrolysis" click here for a bunch of links on this.
Using a carbon rod instead of scrap steel for the other electrode makes less mess and it will not need cleaning.

Good tip about the pressure cleaner.

Hi,

I like the sound of this idea but where do you get a carbon rod from?

Ben.

Hi Ben,
They are carbon gouging rods for using with a welder, they come copper coated. I think ebay has some, there was a thread about them, or maybe in that great long electrolysis thread Ken started some time back. I'll see if i can find it.

I've almost given up on electrolysis though. Its fine for simply shaped parts but for anything with hollows etc the shadowing makes it a very painful process. You have to get your anode in just the right spot to clean in here, then move it to get over there etc.
The weak (25% of the recommended) caustic soda solution is working much better the the lathe parts i'm doing now. No worrying about the plates fouling or hydrogen gas igniting. As Ray and Josh suggested a good pressure was after the soak and the parts come out great. Of course you have to use gloves and a face shield etc whilst handling the solution, although i have found the weak solution to be ok on my hands a splash on the wrist or leg starts to become uncomfortable after 20 sec or so.

Cheers,
Ew

Hi guys,

Well I just had to have a go at this. Ive been meaning to after the fairly long and in depth discussion and thread some time back. Went to the shops and got my washing soda. I don't have a battery charger ATM so I used my variable power supply. Connected the parts to the neg and a piece of scrap sheet metal to pos, turned on the power and adjusted to about 15V and starting adding + mixing in the soda. Boy it does not take much of the stuff to starting a conductive solution. I got it to about 2.5 - 3A

Boy does it go to town! I had previously cleaned this part chemically but this is getting clean enough to eat off!

I'm going to have to set myself up in a more permanent system and use this more often. A good way to find out where all your cuts on your hands are.... dip your hand in while the power is on!

Simon

Good one Simon. Electrolysis works great.

I always do it outside under the shed overhang - I dunno what sort of gas it gives off, but it pays to play safe.

I've found using a piece of thin metal sheet like old metal facia works best on the positive terminal, and I get about the same amps as Simon.

I've not noticed any shadow effect, and the paint washes off uniformly. Looking at the parts to be cleaned it appears to gas pretty much all over, even away from the current stream.

Caustic works OK too, and I've used it a lot in earlier days, but it's dangerous stuff and can easily splash on you.

I haven't tried the mollasses bath yet, but looking on YouTube it appears to work great as well.

Any system that strips pait/rust without muscle power is OK by me.

Cheers

Rob

Hi Rob,

Rightly or wrongly I assume that H2 is given off so I have been doing outside the shed too. I also have been a bit scared to leave it go overnight in case I wake up with nothing left but so far it seems to prefer getting the paint off than attack the base metal? Could be that it's such a slow process that there is plenty of time before you notice any change in physical size, I certainly would not use it to clean a precision fit piece of equipment, but maybe you know more or have more experience with such?

For ##### and giggles I have cranked the voltage up to 30V (current still at 3A) just to see what happens.....

Simon

Originally Posted by simonl

Hi Rob,

Rightly or wrongly I assume that H2 is given off so I have been doing outside the shed too. I also have been a bit scared to leave it go overnight in case I wake up with nothing left but so far it seems to prefer getting the paint off than attack the base metal? Could be that it's such a slow process that there is plenty of time before you notice any change in physical size, I certainly would not use it to clean a precision fit piece of equipment, but maybe you know more or have more experience with such?

For ##### and giggles I have cranked the voltage up to 30V (current still at 3A) just to see what happens.....

Simon

Be interesting to see what difference extra volts makes

I leave mine on overnight and no problem. I don't see any evidence of it attacking the base metal - the only residue in the bucket is paint and rust.

I was quite surprised that it actually lifted acrylic paint on the small vise I'm rescuing. I've previously only used it on enamel.

At a pinch you could probably use a 1 amp powerpack from a Canon printer or some such as the PS.

I missed the pressure washer suggestion in Ewan's thread, so looks like it's been tried before. Certainly makes cleaning up a lot easier.

Rob

It was Josh I think who gave me the idea. Sure beats putting the part in the sink and scrubbing at it.

The anode is sacrificed not the part you are cleaning. You will find it slowly gets eaten away. The big risk is that you connect ot the wrong way and your part starts dissolving......

Ew

Originally Posted by Ueee

The anode is sacrificed not the part you are cleaning. You will find it slowly gets eaten away.
Ew

So far my limited experience agrees with what you are saying but that's what I don't understand. The part being cleaned is attached to the neg, so electrons flow from the part to the anode. Now in school we were always taught that oxidation involves the loss of electrons. This means the part we are cleaning undergoes oxidation. Mind you, the aligator clamp on the anode has been replaced since it has almost disappeared!

Had my part cleaning now for quite a number of hours and it's looking bloody amazing.

I got a 150W solar panel I use for camping. Think I have found another use for it when home.... 17V @ 8A should work nicely

Simon

I have for several Months now and have actually finished the cleaning of all the running gear of a car I am restoring by the use of Molasses and Electrolysis, Have used the electrolysis to clean Aluminium ,and have to pay close attention to the time that it is in the solution or you will lose it, I have a 45 gallon drum in molasses and a 15 lt bucket for the Electrolysis both are plastic of sort,have a few photos of the work that can be done ,that's if the typing allows me to make a separate paragraph, as at the moment can't drop down a line ,this is the Electrolysis Bucket working well ,working from battery charger at about 4-5 amps some of the work from the Molasses and this is one of the 60 lt dust bins that I had going, Just to show what can be done with either, and still can't drop the lines down ,Eddie.