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Trial Number 1

Trial Purpose:

Eight chemistries were tested in phase 1

Date Run:

02/05/1996

Experiment Procedure:

The purpose of this trial is to complete phase one testing for Coatings Manufacturer. Eight different chemistries were tested at maximum recommended operating conditions. Chemistries that show potential will be used in phase two and phase three testing.
Twenty-four 2"x4" 304 Stainless Steel coupons were precleaned in a 20% solution of ND-Supreme in the Crest Ultrasonic console for 20 minutes at 140 F. The coupons were then rinsed in DI water for 2 minutes at 120 F. The coupons were run under air knives for two minutes and then dried for 30 minutes in a convection oven. The coupons were then allowed to cool down for 30 minutes.
After cooling the coupons were measured for a clean weight and then contaminated with both contaminants. The left side of the coupon was contaminated with Basecoat #51144 while the right side was contaminated with #51072. Curing lasted overnight. After curing, the coupons were weighed for a contaminated weight.
Cleaning was performed for 30 minutes at a Temperature of 160 F (+-5 F) in a 600 ml beaker with stir-bar agitation. The stir-bar setting was maintained constant for each chemistry tested. Cleaning time was for 30 minutes. All water-based chemistries were diluted to 50% while the rest of the chemistries were used at full strength. After cleaning, the coupons were immersed in tap water for 2 minutes at 100 F. (Tap water rinsing is not appropriate for some chemistries, but the rinsing will be more carefully evaluated in Phases II and III.) After rinsing the coupons were dried at 140 F in a convection oven for one hour. The coupons were allowed to cool down overnight, and then weighed the next day.

SUBSTRATE MATERIAL: 304 Stainless Steel Coupons
CONTAMINANTS: Durane Base Coatings #51072 & #51144
CONTAMINATING PROCESS USED: Rubbed on with swab and allowed to cure overnight

Trial Results:

Out of the eight different chemistries tested, four show a lifting mechanism (all four U.S. Polychem chemistries).  To evaluate the effectiveness of these chemistries a scrape test was used on the remaining coating after cleaning.  The other four chemistries use a dissolving mechanism on the coatings so gravimetric analysis was successful in evaluating the effectiveness of these chemistries.

GRAVIMETRIC RESULTS

U.S. Polychem Polyspray Jet 790P (50% solution)-#51072 coating was totally removed on all 3 coupons.  #51144 Coating was scraped and could be pulled off of coupon with little effort.

sample # clean mass (g) mass with contamination (g) mass after cleaning (g) contaminant removed (g) Percent Removal
4 60.4205 61.4891 60.9933 0.4958 46.40%
5 59.7666 60.8911 60.4188 0.4723 42.00%
6 60.484 61.4893 61.0261 0.4632 46.08%
        Average 44.82%
        StDev. 2.45%

U.S. Polychem Polyspray Jet 790 XS (50% solution)- Effective on the #51072 (except on coupon #7).  Scrape test showed that #51144 Coating could be pulled off with quite a bit of effort.

sample # clean mass (g) mass with contamination (g) mass after cleaning (g) contaminant removed (g) Percent Removal
7 59.9058 61.0715 61.0420 0.0295 2.53%
8 60.1100 61.2037 60.7258 0.4779 43.70%
9 60.6564 61.5477 60.9692 0.5785 64.91%
        Average 37.04%
        StDev. 31.71%

U.S. Polychem Polyspray Jet 790C (50% solution)- Not effective on the #51144 Coating at all.

sample # clean mass (g)

 

mass with contamination (g)

mass after cleaning (g) contaminant removed (g) Percent Removal
10 60.0143 61.0900 60.4747 0.6153 57.20%
11 60.7083 61.8142 61.1438 0.6704 60.62%
12 60.2780 61.3615 61.2888 0.0727 6.71%
        Average 41.51%
        StDev. 30.19%

Frederick Gumm Cleppo 288-D (50% solution)- Effective on the #51144, but a longer cleaning time will be required to remove the #51072.

sample # clean mass (g) mass with contamination (g) mass after cleaning (g) contaminant removed (g) Percent Removal
13 60.3352 61.8657 61.2669 0.5988 39.12%
14 60.5393 61.6671 60.6663 1.0008 88.74%
15 60.7022 62.1118 61.8616 0.2502 17.75%
        Average 48.54%
        StDev. 36.42%

Ecolink Safe Strip (non-diluted)-Excellent Removal of the Basecoat #51072, A longer cleaning time will be necessary to remove the #51144

sample # clean mass (g) mass with contamination (g) mass after cleaning (g) contaminant removed (g) Percent Removal
16 60.5761 61.6049 60.6560 0.9489 92.23%
17 60.3589 61.4997 60.3737 1.1260 98.70%
18 59.9049 61.1859 59.9882 1.1977 93.50%
        Average 94.81%
        StDev. 3.43%

.S. Polychem 69MC (non-diluted)- Lifts off the #51072 in 10 minutes.  Scrape test showed that the remaining #51144 Coating could be removed easily after cleaning.

sample # clean mass (g) mass with contamination (g) mass after cleaning (g) contaminant removed (g) Percent Removal
19 60.2195 61.3182 60.8249 0.4933 44.90%
20 60.4775 61.4268 60.9516 0.4752 50.06%
21 60.2207 61.2342 60.6523 0.5819 57.41%
        Average 50.79%
        StDev. 6.29%

Terpene Technologies HTF 85B (non-diluted)-Almost as effective as the Ep-921, lower % removal on coupon 22 was due to a high contaminant load.

sample # clean mass (g) mass with contamination (g) mass after cleaning (g) contaminant removed (g) Percent Removal
22 60.0098 62.058 60.0875 1.9705 96.21%
23 60.1060 61.1690 60.1068 1.0622 99.92%
24 60.2287 61.1451 60.2314 0.9137 99.71%
        Average 98.61%
        StDev. 2.09%

 

Inland Technologies EP 921( non-diluted)- The most effective chemistry tested.  Total removal occurred after 20 minutes.

sample # clean mass (g) mass with contamination (g) mass after cleaning (g) contaminant removed (g) Percent Removal
25 60.5203 61.7187 60.5213 1.1974 99.92%
26 59.3011 60.1552 59.3024 0.8528 99.85%
27 60.2420 61.0863 60.244 0.8423 99.76%
        Average 99.84%
        StDev. 0.08%

Success Rating:

Results successful using TACT (time, agitation, concentration, and temperature, as well as rinsing and drying) and/or other cleaning chemistries examined.

Conclusion:

The Safestrip, Cleppo-228C, PolySpray Jet 790C & 790XS were determined to be ineffective and should not be considered. The 69MC and the Polyspray Jet 790P will need a longer cleaning time to remove all of the urethane. The EP921 and HTF 85B performed excellent. The only concern may be the low flash point of the EP921 (146 F). Rinsing will definitely need to be looked in in phase II.

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