We too use the Fluro Finder III for our final audits / approvals, but we find it is harder to use on aluminum surfaces, leaving small yellow dots all over the parts no matter how many times we peen it (possibly we are not mixing enough MEK to the powder?).
In our shop we are using a sprayable dye (layout fluid) for checking our coverage while we are creating the peening program. The dye comes in an aerosol can and we find it easier to work with than the fluro finder. Are there any other types of coverage verification dyes that are approved for the use of coverage verification during source audits?