Trial Number 3

Four of the top eight cleaners from previous trial were selected for testing. Each was diluted to 5% using DI water in 600 ml beakers. Water was used as a control. The solutions were heated to 140 F in a Crest 25 kHz ultrasonic tank.

Four, 3 inch pieces of silver tape were cut from the supplied materials. Optically Stimulated Electron Emission (OSEE) readings were recorded to establish a baseline. Then each piece of tape was thinly coated with Richard Apex D644 CPD drawing compound. The contaminant was applied with a hand held swab and then wiped with a second tissue to simulate the amount of contaminant present after the drawing process. A second set of readings were recorded to determine the effect of the drawing compound on the OSEE readings of the silver tape. Next, each piece of tape was cleaned in a solution for two 1 second intervals and rinsed in a ultrasonic tap water bath for 1 second. Parts were dried for 10 second using a heat gun at 500 F. Final OSEE readings were recorded and compared to the dirty and baseline levels to determine cleanliness.

After establishing a baseline level for the tape, the effect of the drawing compound was found to decrease the OSEE readings substantially. Average baseline level for all pieces was found to be 960 (after adjusting for lower numbers) and the average dirty readings was 191. Cleaning in each solution revealed that the OSEE readings increased, returning near to the initial baseline level. Some readings improved over the initial baseline. This would be due to the pieces of tape being somewhat dirty to begin with. The Beyond 2005 appears to only have cleaned one side of the silver part as shown in the table below. Some of the parts had readings that were not consistent with the majority of the other values for the same piece. All these readings were located at one end of the tape. It was determined that this was were the pieces were held while cleaning, rinsing and drying.

Three products, Oakite Inproclean and Sunshine Makers Crystal Simple Green and Brulin EXP 1400 were successful in removing the drawing compound from the silver tape under the described operating conditions. OSEE was also found to be a practical analytical method for determining cleanliness.