Typically, the highest purity isopropanol that can be found on store shelves in the US is 91%. However, 99% can be special ordered in pharmacy sections. That's the best stuff I've found for cleaning boards prior to toner transfer and for removing flux after soldering. The MSDS isn't scary, either, like it is with many solvents. For removing toner from traces after etching, I use acetone.
--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan <stefan_trethan@...> wrote:
>
> Richard mentioned he used alcohol before.
> I gather US rubbing alcohol is some poor quality isopropanol,
> sometimes with all sorts of crap thrown in, so your theory seems
> plausible. But then most laquer thinner is not exactly a single
> analysis grade solvent either ;-)