hard coat system tips needed

[jjconcepts]

I have currently aquired some equiptment to hardcoat lenes. (the price was right - free). Given the great price, I am having great pains making it work to my liking. I am getting micro bubbles that just won't give up.

The bubbles seem to "just show up" every fey days.

I am using what I believe to be OTC hc.. stainless steel pressure pot, pressurized 5-10 psi.... through plastic tubing... 10 micron wound depth filter... out through a dispensing tip...

Yes, a home made system.

The lens is spun, and excess coating reclaimed into a seperate pot..

What I am hoping for from this board, is currently working ideas, tips, and learnings to help this small guy stop wasting 2 out of 10 lenses..........

[Jubilee]

Make sure you are cleaning the lenses thoroughly with alcohol before attempting to coat. Any tiny bit of debris on the backside of the lens will cause pits or bubbles around it..

Double check your pressures and purge your system if it hasn't been used recently. Air in the line will cause the coating to "sputter" instead of coming out in a stream, and will result in and uneven application and bubbles.

Also make sure you are letting the lens spin long enough to let the coat work its way across the surface of the lens.

How are you curing the coat? If it is a seperate UV oven take a look at the lens before curing. If you see any pits, bubbles or streaks, simply take alcohol and wipe the coating away, and start anew.

Hope this helps,

Cassandra

[jjconcepts]

Further details.. I am using a 30 min "tack free" oven then to a cure oven.. thermocure.. the coating I referred to as otc - optichemicals may be the company(oms) , I recieved some coating from an aquaintence to try out.

I am spinning the lens at a low rpm untill it is fully coated, then speeding it up a little to flatten it out.. I am hardcoating the front surface.

the precleaning for cr is an acetone/ipa wipe for oils, then an alcohol (acs grade) bath.

I believe that bubbles may be in handeling the pot, removing them, if in fact they are air bubbles? Something I am interested in.. what filters, pressures, and application systems are being used?

[Chris Ryser]

jjconcepts said:
I have currently aquired some equiptment to hardcoat lenes. (the price was right - free). Given the great price, I am having great pains making it work to my liking. I am getting micro bubbles that just won't give up.

The bubbles seem to "just show up" every fey days.

I am using what I believe to be OTC hc.. stainless steel pressure pot, pressurized 5-10 psi.... through plastic tubing... 10 micron wound depth filter... out through a dispensing tip...

Yes, a home made system.

The lens is spun, and excess coating reclaimed into a seperate pot..

What I am hoping for from this board, is currently working ideas, tips, and learnings to help this small guy stop wasting 2 out of 10 lenses..........

There is nothing wrong with a home made system, but you got to learn all the tricks.

You use a spincoat system, is it UV cure or is it thermo cure ?

What are you coating and have problems with? CR39, Poly, or high index, or do you have problems with all of them?

10 micron filters are not fine enough you should use 4 microns absolute.

For example on a UV cure CR39 lens you can get bubbles from left over humidity in the lens pores which then will steam up during the polymerization process Result = bubbles.

You can correct this by not coating lenses after they have just be cleaned and washed under water. CR38 is very porous and retains water in their pores. They should be very dry, the just flow some alcohol or acetone over the lens while spinning to throw off any dust particles and let the lens dry again while spinning. A infra red lamp could also help

Another reason for bubbles is the following:

If you pick up air between your resin bottle or container and the nozzle, or you create bubbles by having too much pressure on your system and you creat them during application.
Try to just flow the resin from an upside down bottle though a hose, without pressure and you might just cure your problem.

Another reason:
Some hard coat materials have to be made compatible with the lens material used. For example CR39 has a high surface tension and the hard coat material will not flow properly and tends to ball up. Then the surface has to be pre-treated with a primer. Lenses like a Poly have a low surface tension and the same coating resin will flow properly without re-treatment.

If you re-use the excess coating material which probably has picked up some dirt and dust, you have to re-filter that to 4 microns absolute before using or you invite a lot of trouble.

When we ship hard coat resin, tintable or non-tintable it always ready for use, filtered to 4 microns absolute and ready for use as is. A in line filter is always recommended.

If your problems persist let me know and I will send you a bottle of my material, with my compliments. At that point I can guide you better as I know what my own product can do or not do, or if your application method has to be improved.