Product Incident Report: Crystallization in Rubber Stone Vertical Primer

Product Incident Report: Crystallization in Rubber Stone Vertical Primer

Product Incident Report 

Crystallization in Rubber Stone Vertical Primer

(September 2021) 

Background Information

Several customers reported that our vertical binder (RSVP) binder appeared abnormally and it was observed to have a thick “play-dough” texture rather than the smooth “paste-like” texture. The main issues were observed in batches produced in 2021 where the customers reported issues during the summer and fall of 2021. We instigated e-mail talks with the manufacturer on Sept 17, 2021 outlining the issues with their product.


Fig 1. The image above shows one of the problematic cans of RSVP. Note the manufacture date of 3/1/2021.

Observations

Multiple installers noted that multiple batches of our RSVP binders appeared abnormal than previous batches. The main observation of the installers was that the texture of the abnormal batches which was thicker and the consistency of “play-dough”. Due to this abnormal texture multiple installers noted that the RSVP was more difficult to mix.


Fig 2. The images above are last year’s batch of RSVP binder (left) compared to the abnormal RSVP binder of 2021 (right).

Internal tests were preformed on the 2021 abnormal RSVP binder to see if its performance decreased over the previous batches. The results of the internal testing indicates that the abnormal RSVP batch cured normally despite the abnormal appearance. The addition of acetone to the RSVP also cured normally. The results of this testing is observed in Fig 3.


Fig 3. The image above are notes of the results of internal testing of the 2021 abnormal RSVP binder.

In our correspondence with the manufacturer they indicated that it appears that the RSVP epoxy has undergone crystallization. According to the official product information from the manufacturer the RSVP epoxy has a safe storage temperature range of -4F to 122F. However it has been demonstrated during their testing that temperature fluctuations within this range causes a higher percentage of products to crystallize compared to a constant temperature. The storage conditions of RSVP epoxy in the warehouses at E.W. Industries is under constant temperature controlled conditions and therefore not a contributing factor to the temperature fluctuations. One of the few sources of temperature variability exposure for the RSVP epoxy is during the transportation process where temperatures could drop to subzero conditions within the shipping trucks. A recommended solution to de-crystallize the abnormal RSVP binder is to heat the pail that contains the epoxy to a temperature 194F for one hour. After the entire contents has been heated uniformly above 194F all the crystals formed will disappear. Once all the crystals have gone the product should be ready to use.

Testing

Based on the recommendations from the manufacturer, the affected RSVP cans were heated infront of heat lamps. The methodology for doing this was placing three cans in the heat box with a heat lamp. The cans were rotated every hour so that each can would spend equal time directly in front of the heat lamp for a total of 3 hours of time within the heat box with an ambient temperature of 104.2 F within the box. After the 3 hours of the cans in the heat box were removed from the heat box and allowed to cool overnight. After the contents were cooled, the contents of the cans were inspected and what was found was that the crystallization of the epoxy had indeed reversed as indicated by the manufacturer.


Fig 4. The image above are the effected cans which were opened at 8:00 am and placed infront of the light at 8:15 am with the label facing away from the bulb. These cans were rotated at 1 hour increments so that each can was infront of the light for 1 hour. In total the cans were in the heat box for 3 hours and 15 mins.


Fig 5. The images above are the untreated crystallized cans of RSVP epoxy. Note the small cured “chunks” of epoxy in the viscous mixture.


Fig 6. The images above are the cans of RSVP epoxy after heat treatment and subsequent cooling. Note the smooth texture of the epoxy.

Conclusions

Based on the combination of tests done and correspondence with the manufacturer, it appears that the issues with abnormal batches were the result of premature curing of the epoxy. Fortunately this is a well known issue where there was a solution to revert the affected cans back to a normal state. It should be noted that the affected cans still performed within accepted levels and did not hinder or prevent our installers from using this product normally. The main issues were only visual differences and textural differences (i.e. higher viscosity) and we at E.W. Industries wanted to ensure that the quality of our products were maintained at the highest levels.