I once read that it was a good idea to neither store plastisol ink near an exposed wall that faces the afternoon sun, nor to store it on a source of heat such as a flash cure unit or a dryer. I agree that this is good advice and quite easily carried out. But then the author went a step too far by writing that in the summer months it is best to store plastisol on the floor “as this is the coolest place”. That is where it got a bit silly considering that even the lowest-curing of the low-cure plastisols require 82 degrees Celsius (180 degrees Fahrenheit) before it will gel. Think about that . . . If the temperature in your shop is so high for so long that your plastisol ink is gelling in the bucket because it is not stored on the floor (“as this is the coolest place”), it will be a shop with medical problems long before it’s a shop with ink problems.
Consider the results of an experiment that won a medal for two ten-year-olds at a Calgary science fair a number of years ago. They simulated the shipping of Wilflex plastisol ink in extreme weather conditions from Atlanta to Calgary to gauge the impact on the product. They assumed a slow truck delivery of ten days. One was assumed to be in winter at minus 18 degrees Celsius (zero degrees Fahrenheit) and the other in summer at 50 degrees Celsius (122 degrees Fahrenheit). A third quart (the control) was kept at room temperature. After ten days the two experimental quarts were allowed to return to room temperature and then all three were test printed. There was no noticeable difference between the three in the consistency of the ink, the on-press performance or the cured print.
There’s more reason not to worry. In a discussion once with a technical expert at Avient, he pointed out that it takes consistently extreme heat (say more than 50 degrees Celsius or 122 degrees Fahrenheit) over a period of time (say two weeks) to begin to affect plastisol ink in a sealed container. In most storage environments, even if the temperature reached those extreme highs, it would not be consistently high over an extended period of time as, for one thing, temperatures in most places drop at night. But again, two weeks of 50 degrees Celsius in your shop and you won’t be around to experience how it might affect the performance of your stored ink.
The bottom line? It’s not a smart idea to place ink containers on flash cure units or dryers at any time. It is probably a smart idea to store your plastisol ink away from an obvious source of extreme heat, especially puff inks that tend to expand when they get warm in the container. But don’t lose sleep about summer heat affecting plastisol inks.
And by way of an afterthought . . . storing ink on the floor could be a tripping hazard.