Scratches in CA finish

[law_kid]

I have been having trouble with scratches in my CA finishes of late, and I am not sure why. I have not changed my technique any, but I've noticed when using darker woods that there are still visible scratches, even after using the sanding pads, acrylic scratch remover paste, and buffing steps.

The pads I have been using are Barry Gross' acrylic finishing pads, which have heretofore given me good results. Is it possible that there are defective pads with some improper grits embedded in the pads? Has anyone else had trouble with these pads? I am at my wits' end.

Thanks.

 

[OklaTurner]

Is it possible the scratches you see are in the wood beneath the CA? Are you sanding with the grain after sanding on the lathe?

 

[atbt-steve]

I had the same or similar problem with CA on dark wood. In my case, I took a close examination of my lighter wood pens and realized that all the same scratches were still there, but much harder to see. Attached is my first attempt at a "nice" pen. The finish is absolutely full of scratches. It might hard to tell in the photo, it is hard to tell with the naked eye, but if you know how to look for them, they're plentiful. If the same finish was on a black walnut pen, it would look awful.

To fix the problem, I basically just spend more time with the pads. Stop frequently, especially with the rougher grits, and look for scratches. Do not step up to a finer grit until you remove the scratches. If you have a deep scratch, step down a grit and sand it until you remove it. By the time you get through the first 3 or 4 grits, you shouldn't be able to see any obvious scratches. Then, you should be able move onto the finer grits and give it a good polish.

During my troubleshooting, I purchased a different brand of pads to test and I had similar results. It turned out to be my technique. My biggest hurdle was, learning that scratches need to be removed with the rougher grits, rather than trying to "work through the scratches" with a finer grit. Unfortunately, it means each pen takes more time, but they ultimately look a lot better. Hopefully, this information helps. I was pulling my hair out for weeks, trying to figure out why only my dark wood pens looked like crap, when it turned out they all did. :biggrin:

 

[Dave Turner]

I found a 40x magnifying glass and good light source at the lathe to be my best friends in regards to CA finishing. It's very easy to let a few larger scratches slip by when moving through the sequence of micromesh grits. Unless ALL scratches are removed from the prior sanding stage, they will inevitably show up at the end. This is especially true for the coarser grits.

I find it helpful to turn the lathe off and briefly sand the CA longitudinally along the length of the blank when completing each grit (at least with the coarser grits). This has nothing to do with wood grain. It's to leave the scratches running lengthwise rather than circumferentially around the blank. When you turn the lathe back on to sand with the next finer micromesh grit, it's much easier to see when you've completely eliminated all the longitudinal scratches from the prior grit.

 

[greggas]

With dark material, wood or PR, you need to stop the lathe and and sand, by hand , the length of the blank to remove radial scratches. Time consuming, but a must when using dark material and CA finishes.

 

[TonyL]

Maybe this has posted above, but didn't read all. I understand that many sand wood to 600 before apply CA (and achieve excellent results). I can't get those results by stopping at 600, so I use 800, 1,000, 1,500, and 2,000 I buy the 800 to 2,000 at HD. Then I apply my CA, As Dave stated above, loupes (and USB microscopes) have really taught me much about my sanding/finishing. Many can do without; I can't. Naturally, then I toss the pens on my desk and they get scratched .

 

[flyitfast]

Might look at the buffing wheels as culprits.. They need cleaning after several uses. The wheels will build up with the wax from Tripoli and final wax. Best homemade cleaner can be made with a board that has several nails sticking out one side about 3/8". Hold this against a spinning wheel to clean the buff wheel surface. I usually do it after 5-6 buffing sessions. The little balls of wax will scratch surfaces.
Gordon

 

[law_kid]

Thanks all, for the input. Turns out it was technique. I was both pressing too hard and not pressing long enough with the first couple of grits after applying the finish. I am a little paranoid about sanding through the CA, having done that a couple of times. So I was applying the first couple of pads super quick and not giving the second one enough time to get rid of the first one's scratches (which were likely caused on part by pressing too hard). But pressing lighter with the first grit pad and then pressing lighter and longer with the second grit seems to be the key.

H/T to Barry Gross who talked me through it.

 

[leehljp]

On my post in this thread:
http://www.penturners.org/forum/f28/few-tiny-white-dots-some-times-148091/#post1923018

. . . my description of the "little snowballs" covers this in a way. If too much pressure is put on the sanding, the CA sanding dust can ball up from heat in tiny balls and then scratch the surface, particularly if the CA in not fully "Cured". For me, it happened more at lower temps (when it takes longer to cure), such as below 70°.