Surfacing Troubleshooting

[IChen]

Not at all, thanks for taking the time to provide your expertise on my issue.

This may have already been mentioned in one of the above posts, and I apologize in advance if this post is redundant, but you may be able to tell the source of the "scratches" by inspecting the actual pattern and texture of the scratches.

Generator marks that have not completely fined out will have a more consistent pattern (spirals for a 3-axis generator, parallel curves for a 2-axis generator) and are more "sleek." Random and more jagged scratches or "swirls" would be more indicative of contaminated water or slurry during fining or polishing.

My 1st issue (hairline circular scratches) I'm puzzling over as I haven't seen such a pattern before, they are not swirls nor are they random. They are also extremely faint and only visible under the reflection of an arc lamp, you can only see them if you look directly at the lens while reflecting the light of the lamp off the lens.

My 2nd issue (scratches and sometimes swirls on perimeter of lenses) seems pretty commonplace, most likely due to lack of cribbing and chamfering of the lens blank. They are also only visible when the lens is held perpendicular to under an arc lamp.

My 3rd issue (imprint? of a fining or polishing pad) I haven't seen this type of defect before, the imprint is only visible under the same conditions as the 1st conditions but at a different angle. The imprint seems to be made up of tiny hairline scratches.

So lucky me, all 3 of my issues has to do with scratches, but in my opinion none of them are generator marks. I can try to get some better images, maybe bring in a better camera or something if anything thinks it will help.

If you haven't already done this, inspecting the lens surface carefully under an arc lamp or in a shadow box between each step of the process might also help you isolate the source of the scratches. And, of course, obvious issues, such as tears in polishing pads.

Pardon my ignorance, but what and how exactly do you use a shadow box? I did a little google-fu and found that a shadow box is a wall mounted mirror (or a box of makeup)? I can imagine how it's used but my google-fu didn't really help me much on shadow box usage. Unfortunately no obvious issues such as tears in fining pads or polishing pads, nor did I find anything which I would consider significant in my filtration.

I have seen several very good recommendations above regarding cribbing and chamfering the lens blank to improve water and slurry flow. Remember that over-polishing to work around this issue, in addition to reducing throughput, can lead to other unwanted problems, such as waves and polishing burn.

Best regards,
Darryl

I am actually a little excited about going into work Monday, I have all these recommendations to try out! I will update the thread with my findings as soon as possible! Thanks!