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Ted Mooney, P.E. RET
Pine Beach, NJ

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Hydrofluoric acid substitute

We operate plating facilities in several parts of the world plating nickel/silicon carbide deposits onto high silicon aluminum castings. Typically, during the pre-treatment, we "de-smut" (acid etch) using a nitric acid/hydrofluoric acid solution prior to zincating.

We are about to open a new facility in a location where hydrofluoric acid acid is not available, so I need to find a substitute that will work as well as (or better than) HF.

Any ideas please?

Do a search of this site for ammonium bifluoride for the amount to equal the HF. Infinitely more safe than HF, but it is an additive to nitric acid or sulfuric acid for etching.

Depending on the amount of Si you are talking about, you might try a Ammonium Bifluoride/Nitric Acid mixture. If memory serves me correctly (I don't work with cast Al anymore) I believe we used 8oz/gal concentration.

These guys are right - use ammomium bifluoride. It can be obtained from most of the better chemical supply houses in the UK

Hydrofluoric acid burns

Never use HF anywhere unless trained!
If you do, you MUST have the antidote gel on hand for instant use!

Calcium Gluconate
for HF acid burns

on eBay or

Amazon

(affil links)

Geoff
All good advice
Just make sure that any spec you are operating permits bifluoride.
Remember, it is much safer to handle but you still need calcium gluconate gel available and appropriate first aid training.

Hi my name is Frank Klodner I work in a plant that makes car care products and am looking for a HF replacement, we use it as a wire wheel cleaner but with everyone going green would like to go green myself.