Rik I am 100% sure that I know what Mainlines csl is, and you are correct in saying that it is another organic liquid. A mixture of organic yeasts and a few other goodies. It is sold as a food product, and when it is fresh it isnt quite the same as the Mainline csl. Leave it on your shelf a little while and it changes coulour smell and consistency, and it is then exactly the same. Csl is just what it says, corn steep liquor, its the waste liquid from the soaking of maize prior to it being processed into maize products. Maize glutien is only connected in so much as they are both maize products.