Ive never encoutered anything like this before and im not entirely sure what the issue is.
Im currently printing up a design using plastisol Mixopake Magenta from Union, but when it cures the ink is bubbling in places, like tiny air pockets are occuring within the print, and in general the finish is not desirable. The inks lays down absolutely fine, one coat, flash, second coat, cure. And when curing is when the issue obviously arises.
Is this likely to be an ink issue, dodgy batch? I havnt had the ink all that long, 4 months tops.
One thing I did do is adjust the height of my flash, raising it. Its a small batch and a smnall design so ive been fully curing under the flash dryer to save pumping up my conveyor.
Has anybody had this problem before or know how to resolve it?
I set it higher because I was printing on Fruit of the loom baseball t-shirts which are reknown to scorch. Im now printing on Gildan Heavy cotton t-shirts and have the flash around 4inches above the t-shirt.
Its just a 1 litre pot of Magenta I use for whites, and I have added extender base to it to make it go further. It appears to be printing fine onto the actual t-shirts, I cant see any obvious differences between the appearance at this stage and the thousands of jobs I have done that turned out absolutely fine.
I think I understand where you are coming from though, if I was doing my initial layer and all of the ink was not laying down through the mesh, and then a follow up layer was completely covering the design, would this mean the minute space in between the two layers might expand when held under heat, hence causing the bubbles to appear on the surface?
What temp are you getting the ink up to?
Perhaps you are over curing.
If you are curing on press your platens can get very hot and you may not need to flash as long.
That's my vote. It sounds like you are over heating the ink. The ink is getting too hot to quick. Flash just enough to cure to the touch ( so you can layer other inks on top or around ) then let the dryer do the finished cure. If the ink is clearing the screen fine and the coverage is good before the dryer/heat, it's most likely the heat.
Do you have a heat probe or a way to test what temp the ink is getting up to in the dryer?
This has happend to me before and what I found out is that I has over curing. The first flash has to be cured to the touch and the final has to be up to 320 Degrees. Watch out with the pallents they get hot also and adds to your flash curing.
Good luck.
Printing issue 
