Bakers fluid

Hello,

Is there a chemist out there who can tell me if Bakers fluid will cease to cause corrossion after a period of time? I've soldered together some mild steel tender parts and despite washing thoroughly in running water and brushing over with soap (calcium stearate - alkali?) a fine line of rust at the joints continues to appear. Wire brushing over the last few weeks removes the 'brown' line only for it to return. As far as I recall the flux is zinc chloride and I have a faint hope that there will be nothing left to react at some point - am I correct? Another question is whether there is something I could apply to neutralise the acid but I don't want to get to the opposite situation of suffering an alkali reaction!

Having experienced similar problems, I eventually soaked the components in a strong neutralising solution of washing soda (sodium carbonate), followed by thorough washing in plain water and this did the trick. I was initially worried that the whole lot would come out rusty but this was not the case. Whilst the main ingredient of Bakers Fluid is zinc chloride I believe that there is also a small amount of hydrochloric acid present and this as we know can cause havoc.

Mick

Is Bakers Fluid not similar to Killed Spirits which we used to make at school ( tech ) by dissolving zinc in hydrochloric acid ?

Roy

Yes it is Roy. Back in the good old days before school involved staring at a computer screen all day long!

Rick.

More to the point Rick How many of the pupils of today will remember what they were taught nearly 70 years on ?

I think that another advantage that we had was that our teachers had had working experience they weren't just straight out of college

Roy

I left school 42 years ago so there will be a delay till I try to remember what I learned 70 years ago, however, I do remember there were certain people at school with me who learned nothing at all therefore they won't have the bother of remembering what they learned 70 years on! I do remember that we were taught usefull stuff as opposed to how to be a celebrity/journalist/PR "consultant" / media anylist/ feng shui ist/ don't get me started. So daveb, you had flogging eh? Well let me tell you that was luxury to what we had laddy me boy!

Rick

Had similar problems - cured by washing in “Dish Washer” with normal detergent tabs - gave a good wash after with warm clean water - no further problems . Have done same on copper boiler to remove flux scale.

Make sure Her To Be Obayed is out.

I made sure she was out and she came back early and caught me with a BSA A7 cylinder head in the oven!

Rick

Did someone say biochemist.....rusting once started in steel can only effectively be eradicated by either removing the effected area or by surface treating said area with a chemical with a higher oxidation state. On mild steel the chemical of choice is usually zinc. What actually happens is that the zinc oxidises instead of the metal (this is in a redox reaction).

Hello and thank you to everyone for your advice. I'll try a hot wash in the dishwasher - the bits should fit with the top tray removed and then I'll coat the affected areas with 'Galvafroid'. Hopefully the zinc will come into contact with the steel to 'complete the circuit'.