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-   -   Lines in CA finish (http://www.penturners.org/forum/f28/lines-ca-finish-149810/)

Woodchipper 08-07-2017 04:18 PM

Lines in CA finish
 
I'm taking a break for two reasons- to let the knees quit screaming and to ask a question.
I'm applying Tite Bond Thin CA to a cherry blank. I'm using a paper towel to apply the CA then give it a quick shot of accelerator. I'm noticing that the CA has lines in it like sanding marks. I checked after sanding under a bright light and a magnifying glass to check for sanding marks before applying CA. None there. Before I did something I would regret, I thought I would put the question to the forum. I have MM and Hut Ultra Gloss. What is recommended? Your help is most appreciated.
Using a high RPM but noticed that another thread had one person going down to 500 RPM.

aj r 08-07-2017 04:40 PM

I was having the same problem. Tracked it down to the Meguires plastix polish I was using at the end. Switched that out to a non abrasive polish (Nu Finish car polish) and everything has been fine since.

Might be worth checking it out with the magnifying glass after your micromesh, but before the polish.

elyk864 08-07-2017 04:56 PM

I apply my CA with flexible foam. You can buy it at a hobby store in sheets for a dollar usually. I cut it into little 1.5in x .75in pieces. I also apply my CA turning my lathe by hand. To me it seems it prevents the CA from getting bubbles from the force of spinning. I then sand smooth with 400, 600, 1500, then onto plastic polish. It ends up looking like glass when done.

EDIT: http://www.michaels.com/12x18-foam-s...=Medium%20Pink (I just get the white)

duncsuss 08-07-2017 05:13 PM

Quote:

Originally Posted by Woodchipper (Post 1936629)
I checked after sanding under a bright light and a magnifying glass to check for sanding marks before applying CA. None there.

Try giving the blank a wipe with a small amount of DNA (or mineral spirits) on a paper towel and look again while it's still wet. You might see some lines that didn't show when it was dry -- and the paper towel might pick up some fine dust that was masking the scratches.

You don't say if you stop the lathe and sand up & down the blank with each grit before going to the next higher grit -- it might be worth adding this step if you don't already do it. (Sanding "with the grain" to eliminate circumferential sanding scratches.)

magpens 08-07-2017 05:27 PM

You do have to sand the CA after you apply several coats.

Sand LENGTHWISE with the lathe switched OFF, turning the lathe headstock by hand.

I start with 240 grit and gradually work up to 1500 grit.

If the CA is quite thick, you might have to start with 180 grit.

Using your discretion and experience, you have to sand the CA until there are no shiny patches
using the 240 grit. After that, the sanding goes pretty quickly as you work your way up to 1500 grit, always trying to get rid of all shiny spots.

After the sanding, use a two- or three-stage friction polish.
I use Mequiar's automotive heavy scratch remover first, followed by Novus 3 and then Novus 2 (and sometimes follow that with Plastix polish, which adds a little bit of extra lustre).

Woodchipper 08-07-2017 06:32 PM

I sand from 150 to 400 while turning. I then shut off the lathe and sand parallel to the grain to get any scratch marks out. The blank I had today looked good. I put about 8 coats of CA on the blank with accelerator on each coat. I tried to sand one blank and wound up with a mess. I don't want to ruin this blank as the grain is really nice.
We had two guys in our turning club demo pen making and I don't recall either one sanding the CA. Will look at the blank and go from there. Thanks. Might put the blank aside and experiment with another piece of wood tomorrow. Little League World Series games start tonight so many things are on hold for a while.
Quote:

I apply my CA with flexible foam.
Have lots of it.

magpens 08-07-2017 06:40 PM

My experience has been that you can't get away without sanding CA.

Maybe if you just put one or two coats on, you can leave it unsanded if you like it that way.

And you have to always sand it in the direction of the length of the blank.

That's my experience in 7+ years of making pens.

senfschneider55 08-08-2017 03:33 AM

My 3 cents, Adam, I think got it dead on.
I also turned several acrylic pens and sanded up thru the grits; perfect finish under the mag glass. Then I put a plastx coat on and lo and behold, under the glass were lots of scratches that were not there before. I sanded the pen back and took it to the buff and polish wheels, perfect finish !!
Hope this helps
Irv

Mortalis 08-08-2017 04:59 AM

I have found that if you apply accellerator before there are 3 to 4 self dried coats of CA that white lines and/or bubbles can be more likely to appear. Watch the wood n whimsies video and he explains it also. I dont Plasti-X CA. I will use Plasti-x on acrylic polanks without using any CA. Just how I roll anymore.

Talltim 08-08-2017 05:46 AM

Lines in CA finish
 
Well every one does it a little differently. We sand through 600 and go through the nine rounds of mm on the wood. Then apply the CA and go through the process again through the mm. Then buff with white diamond.

We do the parallel during the wood stage as well.

We only apply accelerator when using medium ca. and sometimes then prefer to apply patience instead.


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