Citric Acid Vs Formic Acid

Both are safe acids to use as there a safe acid but yet an acid that will still burn your skin and yet less caustic. There’s only minor differences as saftee acids have a different mix to them.
Our major chemist here ( Cyclone) might be able to break it down in chemical structure.
All these acids work and many tanneries will use Formic ( very caustic) and citric for different reasons.
I use citric a lot for my bears and greasy animals as it aids in degreasing skins but don’t think that it totally degreases them. Each acid may or may not make skins plumper and or easier to shave.
If your looking into using citric it’s 3 oz per gallon and I would look into many different companies for it as you may find it cheaper elsewhere but I buy in large quantities and that might make a difference depending on your needs.

 

Depending on the volume of skins you tan, it makes sense to reuse the same acid. Just keep it in a closed tote when not in use. Check salinity and acid levels as needed. I buy citric acid from TruBond. Mix it with lipasolve-55 or 77 to aid in degreasing.

 

Citric acid is an organic acid. MUA (Mckenzie Ultimate Acid) like Safety Acid is most probably a mineral acid. MUA and Safety Acids will drop pH lower than will Citric. There are trade offs, however, Citric will leave a pickled hide more plump and easier to thin whereas the mineral acids will produce a stiffer hide but will lower pH further than will citric.

Citric acid is a triprotic acid meaning that it has 3 available acidic protons. It is, however, considered a weak organic acid, by chemist's terms, meaning that all those acidic protons are not readily available in solution but stay with the parent molecule until conditions merit otherwise. This is the reason that a citric acid solution will "bottom out" as some put it. It will dissolve in solution and once a certain pH level is reached it will no longer dissociate into free acid protons.

Citric acid is also an excellent chelating reagent, it will bind dissolved metals thus rendering them inert in aqueous solutions. The effects of hard water ions, calcium, magnesium, even iron will be reduced when citric acid is used.

Mineral acids, MUA and Safety, are most often stronger acids meaning that they give up all available acidic protons in solution. The result, lower pH..

There are qualities desirable in both. I used predominately formic acid for my pickles, formic being another organic acid, and use to get some fluctuations with pH. I liked the way it plumped hides and led to easy, even shaving. Instead of adding more formic to lower the pH I soon found myself adding a little Safety Acid to drop the pH back to a desirable level. I got the desired effects of both acids.. I haven't used Citric but I'd imagine the benefits would be much the same.

 

Thank you sir

 

As Cyclone has stated Citric acid is commonly used in the aquarium hobby to lower PH, GH and KH. As well, it is mixed with baking soda that produces CO2 for aquarium plants. This is done in a separate canister with a CO2 regulator that releases into the aquarium. When you neutralize an acid pickle with baking soda you can see all the small CO2 bubbles form on your hide