tip for tinting those lousy, crappy, good for nothing spincoat src's

**Chris Ryser** · 02-13-2007, 05:10 AM

Originally Posted by Mike.Elmes

How about a tip for tinting those lousy, crappy, good for nothing spincoat src's. A few minutes after immersing them in a tint or UV the air bubbles apppear(on the rear surface) which prevent the dye or UV from evenly absorbing without leaving blotches or orange peel. I have blasted them for producing a machine that causes so many tinting problems. They sent me a product which you add to the dye to reduce surface tension or something similar. As a scratch resistant coating they are better than nothing, on clear lenses. As a coating that needs to be tinted.....it sucks.

On CR39............do not do any backside coating before tintng. Apply the coating afterwards if you have to. Actually a backside coating is not even needed or could apply a scratch resistant slick coat. and you will have no more problem.

Properly cured and un coated CR 39 opens its pores when hot and lets the dye pigments penetrate evenly into the surface.

Breaking the surface tension is a must to eliminate un-even tinting, but you are describing air bubbles which would be due to hard coating with a UV curable resin and having some out gassing problem.

Polycarbonate..............has a surface that can not be tinted, therefore you tint a tintable hard coat that has a thickness of 2 microns (which is very thin). If you get bubbles there is an adhesion problem or the coating is not properly cured. You should look into those problems and correct them.

Also the use of microwaves speeds up the tinting process up to 100 times and lets you tint to darker shades on hard coated lenses than when using the dye pot.

**cocoisland58** · 02-13-2007, 08:19 AM

If I'm going to tint which is rarely, I order "tintable" poly or uncoated CR39 only. I don't know exactly what brand "tintable" poly is but it apparently does not have a coating and it works. The patient is told that this is the only way I can get a decent tint. I don't care to mess around with possible bubbles. If it's sunglasses they want I sell them polorized so they get the scratch coat they need.

**Audiyoda** · 02-13-2007, 08:50 AM

Wow...when I was a lab rat I never once had an issue tinting a spin coated, UV-cured CR-39 lens to a 80-85% density. Poly was a different story - roughly 85% of the poly lenses I tinted I could get to roughly 80% density without issue.

Then again, that's when I was in the lab - as a dispenser I don't generally sell a basic tint unless it's cosmetic. Sunlenses in this office equal polarized.

**EdSheridan** · 02-13-2007, 11:57 AM

BPI sells a couple products that help with that problem. One is called spotless the other is call spotless pearls. We use both in our tints so I'm not sure which one is solving the problem...but they do work.

**chip anderson** · 02-13-2007, 01:04 PM

I love this thread, wish we could get more rival mfgs. debating products.

**Chris Ryser** · 02-13-2007, 01:35 PM

Originally Posted by EdSheridan

BPI sells a couple products that help with that problem. One is called spotless the other is call spotless pearls. We use both in our tints so I'm not sure which one is solving the problem...but they do work.

CR39 has a high surface tension and the use of a surfactant solution will correct the problem. Most tint suppliers do have something along that line.

However if a lens is hard coated on the minus side and the coating is not properly cured evenly on the whole surface you will get spot that can not be corrected because the surface accepts more pigment in on area than another.

If the hard coat on a polycarbonate has been dipped to fast you will have a thicker layer in the part that was at the bottom during the dipping process. This part will tint darker than the other half of the lens.