Etching fluid used as a flux

construction.

I am nearly out off my Fav. A anti lime build-up additive for commercial dish washers. Its Phosphoric acid based but the rep could not tell me at what percentage. Its been good and left no problems for over 10 years and I had a litre for free.

Tommy wrote in article = ...

construction. A

The only "etching fluid" I've used was Ferric chloride which I think is = Hydrochloric acid based and used to etch PCBs. I don't know if you can = use it as a flux. He could possible have meant Baker's fluid or "killed = spirit" as I've heard it called which you use for soldering iron or = steel but also works for brass and copper. This is Hydrochloric acid = based. The problem with acid based fluxes is that unless you clean all = the residue off or wash the joint with an alkaline solution you can get = corrosion in the joint and the solder breaks down. For small stuff like = this I would stick to resin fluxes which are more benign albeit harder = to clean off.=20 Etching in art world terms is usually done with Sulphuric = acid but I've never seen or heard of using Sulphuric as a flux either. = As to the "secret" of soldering the old guy that I learned from always = said it was all in the cleaning of the joints.

By the by what channel was the programme on I would have liked to have = seen that!

Tommy wrote in article ...

The only "etching fluid" I've used was Ferric chloride which I think is Hydrochloric acid based and used to etch PCBs. I don't know if you can use it as a flux. He could possible have meant Baker's fluid or "killed spirit" as I've heard it called which you use for soldering iron or steel but also works for brass and copper. This is Hydrochloric acid based. The problem with acid based fluxes is that unless you clean all the residue off or wash the joint with an alkaline solution you can get corrosion in the joint and the solder breaks down. For small stuff like this I would stick to resin fluxes which are more benign albeit harder to clean off. Etching in art world terms is usually done with Sulphuric acid but I've never seen or heard of using Sulphuric as a flux either. As to the "secret" of soldering the old guy that I learned from always said it was all in the cleaning of the joints.

By the by what channel was the programme on I would have liked to have seen that!

Dilute Sulphuric acid is used by Model enginers as a pickle bath. You place the coper boiler in it to remove the oxidation prior to the silver soldering

Hydrochloric acid based and used to etch PCBs. I don't know if you can use it as a flux. He could possible have meant Baker's fluid or "killed spirit" as I've heard it called which you use for soldering iron or steel but also works for brass and copper. This is Hydrochloric acid based. The problem with acid based fluxes is that unless you clean all the residue off or wash the joint with an alkaline solution you can get corrosion in the joint and the solder breaks down. For small stuff like this I would stick to resin fluxes which are more benign albeit harder to clean off.

You could also try the solder creams which are available from C&L. I believe that they were originally developed for the electronic circuit board market and don't leave flux residues which can cause oxidisation. They are a bit pricey, but do work well - a lot better than the solder paints which use quite an aggressive flux which does require to be neutralised.

It was on the Discovery Home & Leisure channel. A full day of modelling programmes. Meant to video same and unfortunately pushed wrong buttons on VCR:-(

They were concentrating on large models of Ships, Aircraft etc. In this particular series of programmes they were building a large model (approx 8ft in length I think) of HMS Fearless complete with working landing craft and helicopter.

For the finer details like aerials and railings, they used wire and demonstrated the solder construction using this "etching fluid".

---------- Tommy

There are of course several types of "etching fluid" depemding on what you want to etch!.

Ferric chloride is used for etching PCBs because it disolves copper. Phosphoric acid is used to etch glass for the same reason. It is the stuff they use when they mark car windscreens with the registration number. concentrated phosphoric acid is very nast stuff though, so be careful what you use.

Adrian

What sort of etching? Printed circuit boards use (I think) a concentrated ferric chloride solution for etching, not sure if it is pH-adjusted by adding acid as appropriate. Someone has already mentioned phosphoric acid, which forms the basis of Baker's Fluid. From memory this isn't too good for soldering tinplate, though, as it quite happily attacks steel.

David E. Belcher

I believe that some primary school teachers illustrate the effect of Coca-Cola on tooth enamel by putting a recently-discarded baby tooth in a dish of said beverage for a few days - it will completely dissolve.

And all you tools in the near vicinity

Ahhh.....

Of course you are right. It was a long day yesterday...

Perhaps if I hadn't dropped out of A-level chemistry all those years ago...

Adrian