Depends what it is and what you want it to do for example if you wanted to burn through something then 4% of acid may burn through it but 100% of water wouldn't. or in another case some weed killers will only work if you mix less of it into water and if you put more amount into water it just fights its self and cancels it out not doing as good a job on the weed. you need to explain more of what it is the 4% and 100% is of?