Hello.
I have suffered by the cracking issue coming during the hard coat process particularly in 1.6 index,any advice will be very helpful .
Hello.
I have suffered by the cracking issue coming during the hard coat process particularly in 1.6 index,any advice will be very helpful .
some questions:
1 Do you mean that the cracking of 1.6 appeared during the curing of the lenses in the oven or after days?
2 what curing times and temperatures do you use?
3 Does the break only affect the HC layer or has it spread to the lens surface?
4 does the HC have index 1.5?
let me know
Mauro
Ans 1- cracking appear before curing in the oven.
Ans 2- in general 2.5 hrs@125 degree
Ans 3- it's spread to the lens surface
Ans 4- no it's not 1.5,we used 1.6 index varnis for 1.6 index lens & it's only used for 1.6.we have different varnish for 1.5 index.
I would check the temperature of the pre-drying ovens the lenses must not exceed 60/70 ° c
check the thickness of the HC, for a colorable 3-4 microns
Try treating 1.6 with HC 1.5 to see if the same problem occurs
Thanks for your valuable tips.
After dipping in 1.6 varnish it's going to pre- drying oven with 80* temparature.
the drying and curing temperatures depend on the type of HC, the type of substrate, the thickness deposited and whether or not a primer is used.
In general, my experience with colorable HC gives me temperatures around 70 ° for drying and 110/120 ° c for polymerization (2-3 hours).
if the drying phase after deeping in HC is too fast or hot you will have tension on the surface.
Try posting some pictures of the problem
Picture send.
seen from the photos they are not cracks but scratches, given the position I would say caused by the tools you use to load the lenses (tweezers).
Noted sir,I,ll take care of those point adviced by you in future..
Many many thanks for your time & suggestions.
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