Paul,
First, let me explain how soda ash became part of my mix.
Two years ago, I obtained 3 wooden pallets. I washed them with the store bought products I was using at the time. After drying, I stained two of them with common semitransparant stains. The third one I left plain.
I put the three pallets out behind my shed, and let them sit thru an entire season. After a year of weathering, I set out to find my own chems that would clean the pallets the best for a reasonable cost.
After checking out some of the commercially prepared products, I noticed that sodium carbonate (soda ash) was a typical ingrediant. I also found a couple recipes at a chemical suppliers' website to substantiate that.
I tried pure sodium percarbonate, and it did clean, but not as well as some commercially prepared products. I then added soda ash, and the mix seemed to work even better. Then I thought a little detergent would help to lift and float off the dirt better, so I added sodium tripolyphosphate.
I experimented with several different formulations and found the 80-10-10 seemed to work the best. When this mix is applied, it actually fizzes and seems to lift the dirt right up and out.
I'm not a scientist, I have no real laboratory data to boast of, I just tried different formulas until I found one that worked for me.
So I don't know exactly what the hell soda ash does for a fact, but I know that it makes my mix work faster. And I also know that none of the chems I use are carcinogenic or particulary toxic. In fact, this recipe will work as well as most any commercially prepared product.
If I were going to market a product, then I would make it a priority to know exactly what each chemical does, but at this point, all I care about is that I've got a mix that works really well.
If you want to use it, feel free, that's why I posted the recipe.
I think many folks will agree that commercially prepared chems add a significant cost to doing a job. By buying the ingrediants in bulk and mixing myself, I've reduced my chem costs significantly.
The only product I buy ready made, and have no plans to change, is HD-80. It works so well, and in my opinion is cost effective enough that I don't have to worry about it. Plus, I really don't want to mess around blending caustic soda beads and the like, which are corrosive and fairly toxic in higher concentrations, not to mention the hazmat shipping requirements when ordering the raw products.
My .02....