Product Incident Report - PAS that yellows

Product Incident Report - PAS that yellows

Product Incident Report 

Isolated Incident : Pail of non-yellowing binder that ambered during curing 

(September 2021) 

Background Information

After a routine re-roll using our PAS product one of our dealers noticed that our non-yellowing binder significantly yellowed when cured. We requested that our dealer send the pail back to us for further testing an analysis. This issue was only observed in a single pail from a single batch (20-514). This sample was tested internally in which its cure times, cure strength and cure color with a SBR was analysed.

Fig 1. The image is a standard Pool and Spa sample (left) compared to the abnormal yellowed Pool and Spa sample.


Fig 2. The images above are the cured abnormal Pool and Spa binder (left) and a normal Pool and Spa binder (right).
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Fig 3. The images above are the cured abnormal Pool and Spa binder (left) and a normal Pool and Spa binder (right) at a higher magnification compared to Fig 2. Note the yellowing of the abnormal binder and smaller bubbling


Fig 4. The image above is the in-house testing result of combining both the abnormal and normal PAS binder with SBR. 

Observations

The abnormal PAS binder was cured in a stand alone sample in a petri dish and also combined with SBR. The stand alone abnormal sample in the petri dish cured with a yellow coloration (see Fig 2 and Fig 3). Compared to the normal PAS sample, the abnormal PAS sample also has smaller bubbles and is more flexible. The cured SBR samples were also noticeable different, where the abnormal PAS cured sample was much more flexible compared to the normal PAS cured sample. In a separate experiment the cure profile of the samples were tested for where the maximum time of sample workability was studied. The normal PAS sample was not trowelable/malleable after a total time of 3.5 hours and the abnormal PAS sample had a total time of 2 hours before not being trowelable/malleable.

Conclusions

It appears that the abnormal PAS binder cured quicker than the normal PAS binder. Also the abnormal PAS binder also exhibited more flexibility compared to the normal PAS binder. Also the abnormal PAS sample also appears to be less reactive compared to the normal PAS sample, evidenced by the smaller sized of bubbles compared to the normal PAS sample. Based on these combination of tests in which the abnormal binder exhibited discoloration, low reactivity and lower rigidity which are all signs that the sample could have been contaminate in the pail or the wrong product was sent.

Resolutions

One driveway was completed using the abnormal PAS binder and due to the yellowing one installer had to resurface the entire job. E.W. Industries provided credit for the materials and labor for this resurfacing job.