coating cracking on foil stock

[glenner]

Hello does any one know why I am getting mud cracking or alligator skid on foil stock i am told that the coating is drying to fast and it crackes the ink ? I have turned down the dryer It looks great comming out of the delivery but within 15 mins it shows cracking I need help on this

Glenn

 

[lildaddy50]

cracking

If you think you may have a heat issue,try turning off the dryer completely. Crank up the powder and run a 3' lift. Take a lunch break . If it does not crack ,then your dryer still too hot.

 

[glenner]

We still need to dry the coating if we do not , no matter how much powder we run it will set- off. We also have a hard time delivering the stock when the dryer is turned off compeletly. Tends to drag and mark the sheet below. I will try it as A test jst to see if it does-not crack .We already run 3 inch lifts . Thanks for the info not meny people have run foil . Thanks Glenner

 

[aqazi81]

Did you checked the surface tension of the stock.....is it corona treated?

 

[Meny]

In cases of heavy coverage , the dryer's heat can make the ink boil under the coating and crack.
With heavy images , the top skin of theink will dry due to the heat , andunder that , the ink will boil and come out resulting with cracks.
It is much better to use the air knife to dry the top skin and not IR , then you will not get the cracking result , but it will take longer to dry and only smaller stacks.
If you are using IPA in your water system , you may have it too high , resulting with higher mixing rates of water in your ink , and then theink will boil even more and the only way to solve this is to go down sharp with the IPA or use extra air knife power.

With UV , you should not get this as the UV light will go in and activate a proccess that will dry the ink completelly with time (not instant as some think)/
How are you printing ?

 

[glenner]

sorry it has taken me so long to answer back as we have been so busy what we ended up doing was running the job with out coating let it dry overnight and then coated it the next day It worked out well , but we do not have the time for A third pass just to caot A job we have tied everthing that you have sugested , I know that next time we run this job and it will be A couple of times A year as it is A label run it will be the same result .

Thanking you again for all your help

Glenn

 

[turbotom1052]

as mentioned by aqazi you need to have the stock dyne tested to determine if its ready to accept printing. Once the dyne test results show an acceptable level you need to get it right to press before the corona treatment dissipates.