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Paint stripper

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AJAX07/10/2021 17:30:08
284 forum posts
42 photos

I need to remove done paint from various machine parts including cast iron, steel and unknown lightweight cast alloy. I regularly use wire wheels on an angle grinder but on this occasion that's not an option. Can anyone recommend an EFFECTIVE chemical paint stripper that is suitable for machine paints (including enamel paints) and will be safe on these metals?

From past experience i know the modern formulations sold in DIY sides are useless. Paragon paints sell a "professional" stripper (gramos metstrip) but I don't entirely trust it unless someone here can confirm it works. Additionally, there's the issue of whether it could damage the alloy castings.

Brian

duncan webster07/10/2021 17:40:21
3581 forum posts
65 photos

Caustic soda on the cast iron, but it will attack ally

AJAX07/10/2021 17:44:25
284 forum posts
42 photos
Posted by duncan webster on 07/10/2021 17:40:21:

Caustic soda on the cast iron, but it will attack ally

I may give that a try. Any particular technique to use? Can I wash down after with solvent?

Thor 🇳🇴07/10/2021 17:44:51
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1433 forum posts
41 photos

Hi Brian,

If you can buy sodium hydroxide (NaOH - caustic soda) where you live that may be one option. Cast iron or steel objects should be able to survive a dip in strong sodium hydroxide solution. Wear rubber gloves, safety glasses/face shield (preferably both) and protective clothing. Sodium hydroxide must be handled with care, after use you should neutralize it with acid, strong vinegar is one option.

Thor

Oily Rag07/10/2021 17:46:59
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523 forum posts
163 photos

Methyl Dichloride - strips paint off anything (including wood!) but when used with aluminium you need to monitor the process as it will attack the aluminium. I use it for cleaning carburettors as it is the only stuff I know which will remove petrol 'varnish' - the casting come out looking like new after about a 2 hour soak. Works even better when heated. Available from chemical suppliers.

PS don't breathe the fumes and wash thoroughly in detergent after stripping. Wear PPE.

Martin

Edited By Oily Rag on 07/10/2021 17:48:42

noel shelley07/10/2021 17:47:06
847 forum posts
19 photos

As Duncan, and YES caustic soda will EAT alli. Very much depends on the paint type you have ! Noel

blowlamp07/10/2021 18:34:57
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1527 forum posts
98 photos

Wilko own brand paint stripper removed some epoxy two-part enamel very well for me. Put plenty on, leave it there longer than recommended and keep knudging it into the nooks & crannies.

It was far more effective than the premium brand I tried.

Martin.

Baz07/10/2021 18:35:04
606 forum posts
2 photos

I have recently used Dial brand pant stripper which I believe is a brand name of that large diy outlet whose name is two letters of the alphabet. Removed paint from steel and cast iron quite easily.

duncan webster07/10/2021 18:36:14
3581 forum posts
65 photos
Posted by AJAX on 07/10/2021 17:44:25:
Posted by duncan webster on 07/10/2021 17:40:21:

Caustic soda on the cast iron, but it will attack ally

I may give that a try. Any particular technique to use? Can I wash down after with solvent?

I just make up a bath in a plastic container and soak. Afterwards rinse well with clean water. . I use hot water so it dries off quickly. It also degreases, so no need for solvents. As Thor no says, it's unpleasant stuff, so care needed. Make sure you get Caustic Soda, not washing soda

Dave Halford07/10/2021 19:08:56
1816 forum posts
19 photos

Caustic is also available from yacht chandlers as fibre glass paint stripper, turns the paint liquid.

Andy Stopford07/10/2021 19:10:53
104 forum posts
16 photos

Take care when dissolving NaOH crystals in water - the reaction is strongly exothermic and the resulting solution may be hot enough to soften a plastic bucket and allow it to collapse (you may detect the voice of experience here - though it was more of a dustbin than a bucket).

Its best to use cold water, and add the NaOH gradually, with stirring.

It works a treat, and its cheaper than proprietary strippers.

David Jupp07/10/2021 19:13:56
789 forum posts
17 photos

I've used Biostrip previously - you do have to be patient, and it may take several applications, but it is not unpleasant to work with.

Biostrip

Speedy Builder507/10/2021 19:43:28
2441 forum posts
192 photos

Old fashioned car brake hydraulic oil did a good job at stripping paint - don't know about modern oils though.

IanT07/10/2021 19:44:29
1916 forum posts
185 photos

I've used 'Paint Panther' with some success on my machines - which have previously been painted in either enamel or Hammertite. I've also used (the much cheaper) 'No Nonsense' paint stripper from Screwfix. This does work but is slower in action and required more coats than Paint Panther. Both need some mechanical assistance (in parts) with wire wool or scraper. I think it also helps to clean any muck and grease off before using the stripper.

Gloves and googles of course and I normally wash the parts down with white spirit after stripping to get rid of any residues. You can probably use other washes ( hot soapy water?) but that's what I used.

Hope this helps.

IanT

Dave Halford07/10/2021 20:02:23
1816 forum posts
19 photos
Posted by Speedy Builder5 on 07/10/2021 19:43:28:

Old fashioned car brake hydraulic oil did a good job at stripping paint - don't know about modern oils though.

Come to that so does Cellulose thinner.

Clive Brown 107/10/2021 20:04:47
719 forum posts
34 photos

If you need to use sodium hydroxide solution on, say a vertical surface it can be mixed into wallpaper paste to form a goo that will stay in place better than liquid.

AJAX07/10/2021 21:56:21
284 forum posts
42 photos
Posted by Thor 🇳🇴 on 07/10/2021 17:44:51:

Hi Brian,

If you can buy sodium hydroxide (NaOH - caustic soda) where you live that may be one option. Cast iron or steel objects should be able to survive a dip in strong sodium hydroxide solution. Wear rubber gloves, safety glasses/face shield (preferably both) and protective clothing. Sodium hydroxide must be handled with care, after use you should neutralize it with acid, strong vinegar is one option.

Thor

Not sure if it's for sale locally, but I can certainly find it on eBay and doesn't see that expensive. I may need to ask about mixing ratios, but I will read through the complete thread first as there are many replies.

AJAX07/10/2021 21:58:37
284 forum posts
42 photos
Posted by noel shelley on 07/10/2021 17:47:06:

As Duncan, and YES caustic soda will EAT alli. Very much depends on the paint type you have ! Noel

It's rather frustrating that anything likely to work will likely damage the lightweight castings.

AJAX07/10/2021 22:04:53
284 forum posts
42 photos
Posted by blowlamp on 07/10/2021 18:34:57:

Wilko own brand paint stripper removed some epoxy two-part enamel very well for me. Put plenty on, leave it there longer than recommended and keep knudging it into the nooks & crannies.

It was far more effective than the premium brand I tried.

Martin.

Thanks, that's interesting. The reviews on the Wilko website seem extremely mixed (77 x 5-star vs 20 x 1-star) but I might just give it a try if / when I pass a Wilco. However, I can't find a datasheet and the Wilko website just says suitable for "wood to metal to tile".

AJAX07/10/2021 22:07:16
284 forum posts
42 photos
Posted by duncan webster on 07/10/2021 18:36:14:
Posted by AJAX on 07/10/2021 17:44:25:
Posted by duncan webster on 07/10/2021 17:40:21:

Caustic soda on the cast iron, but it will attack ally

I may give that a try. Any particular technique to use? Can I wash down after with solvent?

I just make up a bath in a plastic container and soak. Afterwards rinse well with clean water. . I use hot water so it dries off quickly. It also degreases, so no need for solvents. As Thor no says, it's unpleasant stuff, so care needed. Make sure you get Caustic Soda, not washing soda

Hot water for the solution, or hot water for the rinse? I think it has been mentioned elsewhere this solution generates heat so I'm presuming you use cold water when making your solution.

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