Fining CR39 with poly pads

**Pogu** · 02-22-2010, 09:40 PM

So I screwed up and ran out of CR fine 1 pads:hammer:, lame I know. Well, I still had plenty to surface, and plenty of black PC fining pads and figured I'd give it a shot. The PC pads are way more aggressive so I backed off the time, from 1:30 to :20 for both fine 1 & 2!! It worked great, but I can't shake the feeling that it has to be wrong.

What say you gurus? Am I saving time here, or are these lenses evil and liable to explode?

**Jacqui** · 02-22-2010, 10:12 PM

You're going to die and go to HELL for doing this :D Actually I don't know, if it seems to work, do it. We don't do any poly here so I've never tried this.

**FVCCHRIS** · 02-22-2010, 10:14 PM

I've never played around with using the poly 1st fine pads on Cr. I have however always been able to use my 2nd fine poly pads pretty much interchangeable with the plastic 1st's using my normal times and pressures. I would think the poly 1st fine pads would leave too many deep scratches too get out on the 2nd fine cycle without increasing times and blowing out the powers. Check your powers and final thicknesses when you're through. If it works-work it!

**braheem24** · 02-22-2010, 10:23 PM

pogu, come to ocala I'll lend you some. PM me if you're interested.

**Pogu** · 02-22-2010, 10:23 PM

I'm using PC pads for both fine 1 & 2. I expected a lot of swirls, but w/ the super short fining times they don't seem to be a problem. If this works out reliable, I'm gonna need a 2nd polisher to keep up:p

**Pogu** · 02-22-2010, 10:27 PM

Originally Posted by braheem24

pogu, come to ocala I'll lend you some. PM me if you're interested.

Much appreciation for the offer, but I should be re-stocked by Tues mid-day. Though now I may be onto a new strategy of keeping only one type of pads:D

**braheem24** · 02-22-2010, 10:31 PM

Pogu, I would keep the second fine at the correct times to keep the curves uniform. First fine eliminated generator marks, second fines in the curves, polish eliminates the opacities. First fine is the only one I would cut short.

**Pogu** · 02-22-2010, 11:15 PM

See, here is where my inexperience really comes out. Will a standard check in the lensometer tell me if I'm messing up the curves, or is it more an issue of creating more error away from the OC? The relatively small sample I've inspected so far looked good, but I may be missing somthing....

RT · 02-23-2010, 07:21 AM

Two step fining? I thought that went away 20 years ago.

**DragonLensmanWV** · 02-23-2010, 08:37 AM

Originally Posted by RT

Two step fining? I thought that went away 20 years ago.

Have they finally come up with some one-step pads that really work on all power ranges? I admit, it's been maybe ten years since I tried some, but they were only suitable for low curves, otherwise you got gray around the edges.

**braheem24** · 02-23-2010, 09:47 AM

Tried it 2 years ago, Thought I would save money on pads, labor and time.

I was told the grit changes to a finer grit as the top layer is removed. To make a long story short, it didnt work well enough even with Cr39.

**DoubleD** · 02-23-2010, 10:30 AM

You might "get by" using alternative pads, and may realize you can cut consumable inventory-BUT:
If you apply coatings, for sure AR, any microscopic swirls left will magically pop out. Look at surface very close with high intensity lamp. What you don't see, patient would probably pick up in bright sun!
Denny

**cmhargrove** · 02-23-2010, 12:08 PM

No reason this can't work, but you'll have to ask yourself if it is the best long term solution.

My concerns would be:
1. Do you now need to reset all your values in your surfacing software program to achieve proper center thickness and edge thickness?
2. It might have unexpected results with softer materials like mid-index and high index.
3. Are you getting the best optics you are capable of, or is this just "easier?"

Any time I make a pad change, I generally test all standard materials a few days, then reset my computer values to adjust for new takeoff values and cycle times, then I "let loose" with the new pad. Just my two bits...

**EyeGurl** · 02-23-2010, 11:46 PM

Who does CR 39 anymore? I do maybe two a year that will not shell out for hi index if they are poly sensitive. I do not want the liablity or the complaints in our practice. Yeah yeah yeah refractive qualities - crappy material. Most people we get in complaining about their eye wear from another place had CR 39 and had no clue as to why they picked them. Proper sales and education is important. I cannot belive that has not gone the same way as glass. (last glass pair over 3 years ago, and I used an outside lab, oh I hate that sound and the anxiety of going through it again if the drop ball chipped it.)

~and there is my rant, I never wanna hear of cr 39 again~

**gunner05** · 02-24-2010, 01:48 AM

Eyegurl...

CR39!

**DragonLensmanWV** · 02-24-2010, 07:34 AM

We do about 50 % Cr-39. Been doing it for 30 years. Never had a liability problem. We're not snooty, if they want them in a couple hours, they get to choose CR-39, Trivex, or 1.60. All others, they wait.

**Jacqui** · 02-24-2010, 09:25 AM

Eyegurl...CR39!!

We use mostly CR-39 (some glass). We've never had a liability issue with it.

**braheem24** · 02-24-2010, 10:35 AM

Selling hi-index and avoiding cr-39 is a profit issue not liability.

**ronnie daniels** · 02-24-2010, 12:55 PM

lately ive been selling alot of poly becasue i dropped the price in half because of the pricing we get on it from our lab. Just curious are we aloud to post a RETAIl pricelist for comparison or is that saved for the members only part ;)

**Pogu** · 02-24-2010, 08:13 PM

Originally Posted by EyeGurl

Who does CR 39 anymore? I do maybe two a year that will not shell out for hi index if they are poly sensitive. I do not want the liablity or the complaints in our practice. Yeah yeah yeah refractive qualities - crappy material. Most people we get in complaining about their eye wear from another place had CR 39 and had no clue as to why they picked them. Proper sales and education is important. I cannot belive that has not gone the same way as glass. (last glass pair over 3 years ago, and I used an outside lab, oh I hate that sound and the anxiety of going through it again if the drop ball chipped it.)

~and there is my rant, I never wanna hear of cr 39 again~

Optical shops do, its really quite common.

What are the complaints? Why is it crappy?

**ronnie daniels** · 02-24-2010, 08:38 PM

Originally Posted by EyeGurl

Who does CR 39 anymore? I do maybe two a year that will not shell out for hi index if they are poly sensitive. I do not want the liablity or the complaints in our practice. Yeah yeah yeah refractive qualities - crappy material. Most people we get in complaining about their eye wear from another place had CR 39 and had no clue as to why they picked them. Proper sales and education is important. I cannot belive that has not gone the same way as glass. (last glass pair over 3 years ago, and I used an outside lab, oh I hate that sound and the anxiety of going through it again if the drop ball chipped it.)

~and there is my rant, I never wanna hear of cr 39 again~

im just gonna guess you work at LC lol i talked to a buddy that works at the local LC and he said they dont do anything CR39, wont put lenses in a patients frame, and that their average sales per job is around 700-750?

**albednar** · 02-25-2010, 04:37 PM

Typically by reducing time and pressure you should be ok as long as the surface finish after fining is not so rough that it is difficult to polish out. If need be, increase your polish time a couple minutes above the standard 6 minutes. I would check on your stock removal very carefully so you are not producing lenses that are thinner than required. Hope this helps.

**Pogu** · 02-25-2010, 10:37 PM

I was thinking of lowering the pressure and increasing the time, especially on fine 2, on account of what Braheem said about fining in the curves. But, I've had about 30 go through with the :20/:20 method without any problems save for having to readjust my work routines:) Optics look great, lenses are clear as day, thickness is on target

There has been some pitting around the edges of high minus lenses that don't get cribbed, but I think our cutting blade needs some sharpening.

I'm gonna stick with it for now, I'll update on any problems or lack thereof;)

Oh, CR39!

**Jacqui** · 02-26-2010, 09:29 AM

Originally Posted by Pogu

I was thinking of lowering the pressure and increasing the time, especially on fine 2, on account of what Braheem said about fining in the curves. But, I've had about 30 go through with the :20/:20 method without any problems save for having to readjust my work routines:) Optics look great, lenses are clear as day, thickness is on target

There has been some pitting around the edges of high minus lenses that don't get cribbed, but I think our cutting blade needs some sharpening.

I'm gonna stick with it for now, I'll update on any problems or lack thereof;)

Oh, CR39!

**eyesonjohn** · 03-02-2010, 12:35 AM

Originally Posted by ronnie daniels

im just gonna guess you work at LC lol i talked to a buddy that works at the local LC and he said they dont do anything CR39, wont put lenses in a patients frame, and that their average sales per job is around 700-750?

your buddy lies