Test methods, please

[janezl]

Hello!

I am looking for advice/information, how to:

- evauluate if UV ink or varnish is fully cured after being printed on sheetfed machine
- evaluate slipperinnes of ink/varnish, to assure conditions for further processing (transport on filling line)

What are test methods, devices, consumables, to have repeatable/comparable results.

Thanks, Janez

 

[Cornishpastythighs]

There are a few 'press side' tests that the operator can perform to evaluate cure of UV. None are very scientific. *Fingernail test- speaks for itself, if the ink/coating can be scratched off then chances are cure is not too good. *Thumb test- Press thumb on sheet and twist, if ink smears cure not good
*cross hatch and tape test- used more for adhesion than cure but will give some indication of problems.
Dont confuse poor adhesion with poor cure, fully cured ink can have poor adhesion to the substrate.
Other cure tests involve the use of nasty chemicals and are not usually done press side.
For slipperyness you need to measure 'slide angle or COF' This equipment measures the angle at which a printed/ coated sample will slide down an incline.The lower the angle the slippery the sample is the high the angle the less slippery the sample. Hope this helps