So what is lye and it's use?

lye is an alkali metal hydroxide. The word lye most accurately refers to sodium hydroxide (NaOH)[citation needed], but historically has been conflated to include other alkali materials, most notably potassium hydroxide (KOH); . . . To distinguish the two, sodium hydroxide may be referred as soda lye; potassium hydroxide may be referred as potash lye.
https://en.wikipedia.org/wiki/Lye

Safety

Before making consider lye is corrosive to skin and many metals. Keep vinegar nearby to counteract the alkali should in get on skin or other material.

Storage

Although most stainless steel is fine, plastics containers of either PP (polypropylene) ♷ or HDPE (high density polyethlyene) ♴ maybe more suitable

Anything made from these plastics -- PP (polypropylene), HDPE (high density polyethlyene), or LDPE (low density polyethylene). Absolutely do NOT use the clear plastic drink bottles (PET or PETG, polyethylene terephthalate). It seems the PE in PETG should be fine, but PETG plastics do NOT work with NaOH.
https://www.soapmakingforum.com/threads/lye-master-batching-advice-wanted.60822/

My interest is largely in Ca(OH)₂ and KOH in wood ash. (potassium (k) and calcium (ca) hydroxide (OH)). Soaking in water will convert Ca₂O to the hydroxide.
(Ca + O + 2H + O ⇛ Ca + 2(OH) )

As Ca(OH)₂ is not very soluble in water the resulting lye may be more Potassium based as KOH does dissolve in water.

Calcium Hydroxide

Given the caustic nature of lye and it's reaction with aluminium it is wise to take extreme care of the end product, especially if the water is evaporated to leave 'pure' KOH

My use will be fornixtamilzation,the process of modifying maize kernels. Other common uses are curing green olives and making soap, neither of which I have any interest in currently, having no olives and no spare lipids (fats and oils)

Type of wood

Hardwoods such as oak and maple tend to produce wood ash with a higher calcium and potassium content, while softwoods such as pine and spruce produce ash with a higher magnesium content.

Production

I have come across a few sets of instructions

Video by Chef Shaun Sherman
A soap maker( A text description )

In the first the alkalinity is tested with a device, in the second with a potato to test the specific gravity through flotation.

and

Generally, 10 cups of ash = 1 gallon of lye water.
primalsurvivor.net/wood-ash-soap/

Collecting ash

• 15th Oct 2024: Sieved another batch now have 1Kg of ash
  

  

• 11th Oct 2024: Sieved another batch and have 750g of ash
• 10th Oct 2024: Sieved the 500g of ash down to 400g. Not the best of sieve, veggie colander �
• 4th Oct 2024: Collected 500g of ash. Yet to sieve out the carbon bits. . . .

Making Lye

• 16th Oct 2024: Try 450g (1.23Lt) ash to 3.62Lt rain water. Approx 1:3 ratio as described in Video by Shaun Sherman
• 16th Oct 2024: 12:30 to 13:40 Boiled water then add as (9 cups) then simmered for over an hour: leave the lye to lie overnight.
• 17th Oct 2024:Scooped over 1Lt from the cooking pot. Nice yellow colour. Have more from squeezing ashes through muslin -cleaned my hands. ��
  

  

  
  

  

• Specific gravity: Small potato sank, maybe a heavy potato given it's one of those 'pink fir' type. So used battery hydrometer and have reading of 1.2
• Soaking ash overnight in another 1.6 to 1.9 Lt. of rain water. Once this is filtered off I will use it to make the first batch of Nixtamal. Maybe use 500g maize �
• 18th Oct 2024:Maybe 1.6 to 1.9Lt from the first filter and from yesterday's second cold soaking another 2.3Lt with some colour.

  

• 26th Oct 2024: From the raw ash I had some was used to deter mice etc. but now have a full 3Lt tub of unfiltered ash

On to the Nixtamalization