Quote:
Originally Posted by TrevorG3VLF
I have a small tin of Fluxite, only 60 years old. It seems to work quite well if the surfaces are clean.
More recently I bought a little pot of LA-CO regular soldering flux paste labelled non-acid, non-toxic. It seems to be a little better than Fluxite. I have e-mailed the makers (US) to see if is is suitable for electronic circuits but answer was there non. Does anyone know if this is corrosive?
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La-Co flux is described as:
"Self-cleaning flux for use on copper, brass, lead and zinc and on both water and gas installations. Acid-free, non-toxic and free of lead and zinc chloride".
Describing it as 'acid free' suggests that it is benign and innocuous, but that's not quite so.
It's been commonplace for some years now for all plumbing fluxes to be 'self cleaning' - in other words, you can apply it to tarnished copper capillary end-feed pipe fittings and pipe without first cleaning with steel wool. If it can remove oxide, if left on anything on which it's been used, whether it's copper pipe or electrical connections (valve-holder pins etc), then over time, it will be corrosive. If you look at copper plumbing pipes installed by lazy and inept installers who haven't removed the flux with a wet cloth while still warm, you'll see green corrosion on the pipes and fittings. Tue, it may not eat right through the pipes, but it's not desirable. See pic 1 below of green deposits on pipes under a sink unit.
Fortunately, as it's soluble in water, after a joint has been made, it can be removed with a wet cloth, cotton bud, whatever.
As to the ingredients, they're listed in Control of Substances Hazardous to Health (COSHH) Datasheet:
A) Ammonium Chloride 12125-02-9 7 – 13 235-186-4 Xn, Xi R22, R36
B) 2-hydroxyethylammonium chloride 2002-24-6 7 - 10 217-900-6 Not classified
C) Not classified Stearic Acid
Source:
https://www.colglo.co.uk/files/Lead_...lder_COSHH.pdf
It's been around a long time - toxicity tests were carried out in 1962:
The Acute Toxicity Data for the mixture showed that it did not irritate the skin of dead rabbits, which might be reassuring for live ones:
(Tested by Rosner-Hixson Laboratories; August 30, 1962)
Irritation: The product is essentially non-irritating to the eyes and skin. Application of the product to areas of intact and abraded rabbit skin produced no signs of skin irritation (Rosner-Hixson Laboratories; Aug 30, 1962).
Quote from Wiki:
Ammonium chloride is an inorganic compound with the formula NH4Cl and a white crystalline salt that is highly soluble in water. Solutions of ammonium chloride are mildly acidic. Sal ammoniac is a name of the natural, mineralogical form of ammonium chloride. The mineral is commonly formed on burning coal dumps from condensation of coal-derived gases. It is also found around some types of volcanic vents. It is mainly used as fertilizer and a flavouring agent in some types of liquorice. It is the product from the reaction of hydrochloric acid and ammonia.
(90% of it globally in in the production of fertiliser due to the nitrogen content).
https://en.wikipedia.org/wiki/Ammonium_chloride
https://www.screwfix.com/p/la-co-flux-475g/32957
Hope that's of interest.
(No animals were harmed in the production of this post).