We just received a copy of Rolls-Royce specification RPS 702 that has several points worth comments as concerns materials that are approved for use.
Under paragraph 18.104.22.168, certain materials listed on AMS-2644 are The Penetrant Professor now specifically listed as approved. This will make things easier for many penetrant users working to Rolls-Royce specifications.
Under paragraph 22.214.171.124, non-aqueouswet developers are approved, so long as they contain 50% or less of isopropanol. This point is interesting in light of the recent work reported by CASR. This work, conducted at Iowa State University, found that nonaqueous developers that were isopropanol based produced brighter indications than similar developers that were acetone based. Assuming that this is true, one might be in the position of deciding whether to use a developer that dried fast, but produced less bright indications, or to use a developer that produced brighter indications, but dried slower. It is also interesting to note that some OEM’s have outlawed acetone on their premises. Acetone is significantly more flammable than Isopropyl alcohol which is something else to consider. But in any event, Met-L-Chek® D-70 non-aqueous developer is isopropanol based, available in 12 oz.(300ml) and 16 oz.(400ml) aerosols (12 cans to the case) and contains less than 50% isopropanol, therefore meeting the RPS 702 requirements, and producing brighter indications than developers based on acetone.