The obvious reason, is to prevent skin deterioration,after being in acidic bath. First thing to remember, is, the stronger the acid, the harder it is to neutralise. The neutralising process NEEDS to remain flexable. Always use baking soda! Its safe! When using stronger acids, increase the amount of soda, to at least 2oz per gallon(3oz OK), and increase the time in the bath(up to 1hr). 30min, and 1oz, DONT cut it! Thicker skins, also NEED additional time and soda.If you think about it, its just common sense. Neutralising the mineral submersible tan(excluding EZ100) An example would be Lutan. Neutralising this tan is importantant in the following ways. 1. The recommended finish pH, actually FIXES, or locks in the tan. Without proper FIXING, the tan can be washed out. Mineral tans are attracted to acidic collagen, an are neutralised AFTER the tan is introduced. 2. The oil you apply to this type of tanned skin, FIXES to the tannage, so it remains in the skin to some extent, and cant be washed out. Skin remains soft. Without proper neutralisation, washing before mounting, will wash out the tannage, and oil. Drumming and pulling in sensitive areas will take place. You mounted raw hide. The PAINT-ON TAN: synthetic(include EZ100 in this group-its a submersible, but a synthetic) 1. Most, if not all of the synthetic tannages used in todays taxidermy tans, REQUIRE a skin to be FULLY neutralised before application. This type of tan, unlike the mineral, is attracted to collagen with higher pH values.(mineral tans are attracted to acidic collagen) 2. NO TANNING TAKES PLACE, without through neutralisation. REMEMBER THIS! So to make a LONG STORY short, you neutralise according to the type of acid you pickle with, the type of tan you use. and the skin being neutralised. EXAMPLE: Safety acid=STRONG 2oz soda per gallon,and 45min to 1 hour in bath for most skins Citric-1oz 30-45 min should suffice on thin skins. Know your acid strength, know the tan, and adapt to skin size and type! (Boar- tight weave collagen=up the time and soda) Gentle aggitation, and warm water, is ALWAYS beneficial! Hope this helps someone! P.S. - Dont worry about the pH of the neutralisation bath, when using baking soda. I have learned over the years, baking soda is very forgiving on epidermis, hair, etc!