Here is what I wrote about this very subject:
Dilution ratios require some "algebra" math to get the "correct" ratio for the mixed solution of product-to-water. For example:
A common ratio of 1:4 is really 5 parts: 1 part product and 4 parts water. That means that a 32 oz bottle of mixed solution is really 6.4 oz of product and 25.6 oz of water to get 32 oz. This "math" applies to ANY solution ratio. A 1:10 ratio is really 11 parts, a 1:8 ration is really 9 parts, (etc.) So , if you divide your bottle size or final oz quantity desired by the parts number (IE, ratio sum), you will get the amount (oz) of product needed for that ratio mixer.
One other factor in mixing chemicals into water is to do just that: pour in the water FIRST, then the chemical. This is a high school chemistry lab safety practice as it allows the water to dilute the chemical as it is poured in. If it is done in reverse, exothermic (heat) reactions caused by chemical reactions between the water and the chemical can occur, causing the chemical to boil out of the container. This is very true of any strong acid (like sulfuric acid) and water.
How do I know?? I did this in high school by pouring hydrochloric acid into a large test tube and then trying to dilute it with water. The acid immediately boiled out of the test tube, ruining a new high school track team shirt I had on and causing minor burns to my shoulder, even after the quick application baking soda to neutralize the acid. It could have been much worse had it gotten on my face. (These were the days before rubber gloves and face shields where required in high school labs.) Needless to say, it is a chemical mixing safety lesson I have NOT forgotten. This is especially true using Meg`s Detailer Line D140 Wheel Brightener, which is highly acidic. I would also implore you to use safety eye goggles or plastic glasses when mixing, as the inadvertent splash of chemical into the eyes can be avoided this way. As the saying goes, "Safety is no accident".
I also think that this is why many manufacturers suggest "odd"-numbered ratios like 1:3 or 1:7. because it becomes a summed even-number of TOTAL mixture parts: IE, 1:3 ratio for a quart (32 oz) is 8 oz of chemical and 24 oz of water.), 8 into 24 = 3 and 8 + 24 = 32.
Anyone interested in using the metric system for this? It`s a lot easier with a base 10 system!! Didn`t think so.... (the rest of the world is laughing at the USA for our continued adherence to the British/English Measurement System for commerce/business and engineering. Of course when was last time you went to Home Depot and asked for 50 x 100mm wood stud, or the meat department at the local grocery store and asked for 500 grams of hamburger?? I think not!))
