I see this often, a contractor wants to save some $ so they think they can make up their own “bubble-test” solutions. However, not only is this a very bad idea from a QA perspective, it is actually NOT TO CODE, as ASME Section V, MANDATORY APPENDIX I BUBBLE TEST — DIRECT PRESSURE TECHNIQUE, I-1032 BUBBLE SOLUTION contains a very specific and clear statement…
(emphasis by me)
I-1032 BUBBLE SOLUTION
(a) The bubble forming solution shall produce a film that does not break away from the area to be tested, and the bubbles formed shall not break rapidly due to air drying or low surface tension. Household soap or detergents are not permitted as substitutes for bubble testing solutions.
(b) The bubble forming solution shall be compatible with the temperature of the test conditions.