Personally I use the isopropyl alcohol that is 91% but the 70% should not make a difference. As for the windshield washer fluid I use just the cheapest summer blend stuff Wal Mart sells. I do not get real technical with the mixing. I have a jug and pour it half full of the Windshield washer fluid and then fill the rest with the alcohol.. I use it is a spray type bottle.

As for the kind of powder your shooting, there is a concern that petroleum based products are not to be used around black powder. It creates a tar like substance. I have used this mix shooting every kind of powder there is and never had a problem. The nice thing about the alcohol is it evaporates out of the barrel almost as soon as it is used it seems.

I wet a patch and swab both sides of it down the barrel. A little hint, swab in short strokes and just keep getting a longer stroke as you move down the barrel. If you push that swab straight down the bore, there is a good chance it will get stuck. If you work it in short strokes, it will clean the fowling better and not get stuck. After working both sides of the wet patch I run two dry patches (these are my next wet patch swab if they are not too fowled).

Then just load as normal.