Stripping stuff with Caustic Soda

Be real careful, guys... I don't wanna read about anyone doin' themselves damage cuz they didn't follow all the excellent advice up there ^ ... This stuff is for realz...

Caustic Soda is perfectly safe IF

You don't inhale the fumes
Get it on any tissue at all. Eyes, skin etc etc

If you wear gloves, are careful with your eyes and don't breath it in its fine.

Don't store the solution when you're finished with it. It can burn through some kinds of plastic bottle.

An ex of mine managed to seriously burn both her hands when she tried to store some caustic soda in a plastic bottle and it ate through and poured onto her hands in a matter of seconds.

On that subject, when I was 12 I was dicking around as kids do and managed to get a single grain of powdered caustic soda on my tongue (don't ask). It burned a hole right into it and took months to heal. I like to think I have become more intelligent with age.

^ yeah good point with the heat, did it in school with a fume good in a glass beaker, can get well over 100 degrees. Following that experiment at school we used to make little balls of tin (well aluminium) foil, and fill a thick bottle up with the solution, then do the old suspend the foil in tissue and screw the lid on thing. throw and run, really shit idea it was thinking about it.

At least with the dry ice bomb you weren't as likely to get a faceful of corrosive fluid.

Ahhh, the good old days. Cue memories of arseing around on the railway and accidentally setting myself on fire a few times.

I like to think I acted like an idiot so others didn't have to. Greeeeeat days.

Sodium into water :)

Yeah was completely stupid !

Ooooooooooof...I shall use the coca cola method...1/2 for me alloy bits, other 1/2 for me vodka bottle... :-)

I just dissolved an alu seatpost with caustic soda, but now I have a big plug of white crusty stuff inside the seat-tube. Water won't dissolve it, and it's quite resilient to physical attack from a metal bar - any chemists here know what it is and how to get rid of it?

Perhaps heating the tube? Presumably it won't expand as much as the steel will...

More caustic? I'm guessing the white stuff is aluminium oxide, and my GCSE knowledge tells me that aluminium oxide dissolves in excess sodium hydroxide. No idea how this works in practice, but trickling some hot caustic over it should dislodge it.

you may have more luck with ammonia....try something with that in.....most window washers have at least a little.....

where can u buy caustic soda?

i left my tandem frame soaking in caustic for 2 days came up pretty good

you may have more luck with ammonia....try something with that in.....most window washers have at least a little.....

I bought some household ammonia and poured it in neat - seems to be working!

The whole seattube was blocked solid by this stuff, whatever it was.

Just a shot in the dark... has anyone ever successfully preserved modern vinyl rim decals, i.e. removing without stretching, breaking or ruining them, keeping them on some backing paper, in order to strip ano off a rim but be able to keep and re-apply the decals?

I have removed more rim decals than I can remember and I'm yet to get one off with all the glue intact let alone keeping the decal in shape. I reckon you'd be better trying to get reproductions or maybe going to the manufacturer for spares? What rims are they just out of interest?

Slice them away from the rim with a razor blade?

caustic soda vs cutting the seatpost out with a padsaw.

padsaw is two hours hard work. you might cut into the seat tube. you have to buy a specially long blade, or several.

caustic soda takes ages. you will total the paint however careful you are. you will get chemical burns on your skin. you will damage the paintwork on anything that happens to be nearby (ie, other bikes). you will wreck the kitchen utensils you use. you will spill soda on exactly the thing you don't want to spill it on. you will end up with a lot of strong toxic chemical to dispose of.

next time I am going to use a saw.

but there wont be a next time because in future I am going to use the right size seatpost.

And grease. Always use grease. For everything.

Question:

If I put a set of Sugino 75 cranks in caustic soda (to then polish them up with a buffing wheel), will the corrosion damage the threads and/or the square taper?

nope, keep a keen eye on it as it only takes seconds to remove the anodising, I rinsed my stuff in water straight after they went black.

like how many seconds? last time i did a chainring i left it in for a fair few minutes.

Chainring = steel? Alu cranks will need very little I'd say, thought I did leave a stem in it for 5 minutes once.

If you're polishing them I would do it by hand with sandpaper - the caustic soda leaves a fairly rough finish that needs sanding out anyway.

I've done cranks with 400g to get the anodizing off, then work up the grades to 1,500 grit, polished first with Autosol and then with G3 - looks like chrome. A stiff sponge makes a great sanding block for curved items. Keep the paper wet and add a touch of washing up liquid and the paper will last much longer.

The buffing wheel will remover the anodising. It doesn't take much to remove it.

Good shit guys, thanks.