so my friend just boiled 50 grams of acacia confuse root bark in 100 ml of water and 30 ml of vinegar for about 40 minutes. This is his first a/b tek so im wondering if 40 minutes of stove time is long enough for that amount of bark.

To make certain you get all active ingredients out, you should boil it until blood-red, strain off the liquid, add more acidic water, and repeat the process this til the liquid no longer turns as red anymore. Collect all the liquid then reduce it down to manageable amount through more boiling. If you need more detail, search google for thick-light's tek.