Sanding thru thin CA finish problems...

[alankulwicki7]

Hey all,
A few months ago, I tried finishing my pens with thin CA. After a little experimenting, I was able to get good results.
Now a few months later, I'm trying to replicate my process and keep sanding through the finish. I put on about 10-12 coats of thin CA and while it comes out looking nice I just need to get that final gloss.
I've gone straight to the micromesh and then I've also lightly wet sanded with 1000 grit before micromesh. Both times I end up sanding through the CA.

I'm using very little pressure when sanding but that doesn't seem to help

Any advice? I've got a couple of pens I need to finish up and I need them to look great!

 

[lorbay]

Well my problem was I was not getting enough on. It seems like I was always have trouble on the high spots. After my ca I sand dry with 400 or 600 to get it all level and then wet with all the mm grits.
Lin

 

[George417]

I use medium CA and don't have any problems with that

 

[longbeard]

When finished turning wood, i always try for about 005 thousands under final dimension. After final coat of ca, mic the ends again. This will let you know how much sanding is needed to get to final dimensions. I always start with the first mm pad wet. I never dry sand ca. After the first mm pad, i will mic the ends again just to be safe. Just my way of doing things. Hope it helps. I only use med ca also with a mist of accellerator after each pass of ca.

 

[Jim Burr]

Make sure you are using the same glue, thin, medium what have you. Temp and humidity play in to it. Just smack it on and wipe it off!

 

[NittanyLion]

Doug,

You're either taking too much off with MM or not using enough CA. For me, 10-12 coats of thin is the minimum I would use( if using only thin). I would suggest moving to medium, at least for several coats. Also, you would be surprised how aggressive the first few MM pads are and how much they take off. It doesn't take much pressure or time with each of the first few MM pads. Too long, or too much pressure will really take down your CA. Good luck!

 

[edstreet]

Lets see

A) CA viscosity to thin for a proper coating, less you induldge excessive time and agony. Yes it can be done but well you get the point.

B) Excessive sanding. Don't worry, many here seem to be guilty of doing this part, sand to much when they should not be.

C) 10-12 coats? You mean 10-12 drops?

Dare I mention you dont need micro mesh for a CA finish?

 

[jmm666]

I have had the same problem and as already mentioned, there are two causes:
1) too little CA on the pen
2) too much taken off with sanding
To solve 1), I use a few coats of medium on top of the thin and don't rub it on too much. Just enough to apply it and smooth it out.
To solve 2), use light pressure on the micromesh pad for just a few seconds. I count to 3 for each pad and then move on to the next one.
Just experiment until you get a process that works. Then, repeat, repeat, repeat.

 

[edstreet]

The other thing to solve #2 is only go up to 600-800 grit on the CA finish. After that you can skip everything and goto the final part, be it buffer or liquid polish. No need for micromesh or sandpaper.

 

[sbwertz]

I use the first six micromesh grits before applying the finish, then use 7, 8, and 9 after applying the finish. I use a little plastic polish if I want more shine.

 

[tomas]

I use 16 coats of medium CA. Before finishing I sand with Abranet up thru 600, then wipe down with DNA. If the CA is not smooth after application, I smooth with an extremely light touch with my PenPro - all you should see is a little fuzz. I then apply another coat of CA and then MicroMesh wet thru all colors.

Tomas

 

[plano_harry]

I agree with Tomas. 16 is my minimum for thin. I hit my blanks with 400 and often 600 abranet radial and longitudinal then DNA before I start laying on the CA. This minimizes the high spots I would likely sand through.

I lay on 4 coats then accelerator, then 4 more ....repeat. When you get good with the thin, you will have a blank with virtually no ridges and doesn't look like it even needs sanding.

After a several minutes to harden, i hit it lightly with 400 abranet wet in both directions, wipe down and give it a careful look. If all the little shiny spots are gone, that means I am level and I am moving on to MM wet. All you need to do with the MM is take out the previous grit scratches, so it doesn't take much.

I can't remember the last time I sanded through 16 coats, but i wouldn't try 12. If the pen is going for more than $100 I will probably put on 20

I used to do 3 thin and 10 medium with ridges and I would screw up about 30% on the time. Wasn't the same in summer and winter, etc...My friend Martin suggested 20 thin and I have never gone back.

Good luck,
Harry

 

[edstreet]

I agree with Tomas. 16 is my minimum for thin. I hit my blanks with 400 and often 600 abranet radial and longitudinal then DNA before I start laying on the CA. This minimizes the high spots I would likely sand through.

I lay on 4 coats then accelerator, then 4 more ....repeat. When you get good with the thin, you will have a blank with virtually no ridges and doesn't look like it even needs sanding.

After a several minutes to harden, i hit it lightly with 400 abranet wet in both directions, wipe down and give it a careful look. If all the little shiny spots are gone, that means I am level and I am moving on to MM wet. All you need to do with the MM is take out the previous grit scratches, so it doesn't take much.

I can't remember the last time I sanded through 16 coats, but i wouldn't try 12. If the pen is going for more than $100 I will probably put on 20

I used to do 3 thin and 10 medium with ridges and I would screw up about 30% on the time. Wasn't the same in summer and winter, etc...My friend Martin suggested 20 thin and I have never gone back.

Good luck,
Harry

How thick is 12/16/20 coats? Is that drops and not coats? Is this layers?

 

[Dave Turner]

I find it helps to take frequent caliper measurements of the diameter, at both ends and also the middle of the blank. Do this after prep sanding and after every few coats of CA. This gives you a feeling for how thick your finish is and how many coats you actually need of any particular finish (thin CA, medium CA, etc.). Do the same measurements after each grit of sanding / micromeshing (at least for the coarser grits, it doesn't change much on the finer grits).

After you do these measurements on a few pens, you get a good feel for what's actually happening when using your own personal technique.

That being said, I prep the surface for CA by sanding up to 400 grit. I put my CA coats on (I use 12 coats of medium CA with paper towel method), then I do my initial dry sanding of the CA with 400 grit Norton 3X sandpaper. I sand it just enough to get rid of the surface ripples from the CA application. You can feel it on your sandpaper when the surface becomes smooth and you can see it because all the shiny streaks are gone when you wipe the sanding dust off. If the CA surface was extremely rippled or irregular, I may give it a quick shot with 320 grit Norton 3X before going to the 400 grit. If the surface is that bad, I generally prefer to smooth it with a skew first, using it as a scraper and just skimming the high CA spots off.

Once I've dry sanded to 400 grit, I switch to wet micromesh sanding, starting with the "Green" Micromesh pad as the first one I use, which is equivalent to 600 grit. I use this one very sparingly and once I get a good "slury", I'll quickly move on to the Black micromesh. Lately I've been starting with the Black rather than the Green with good results. I find with the micromesh pads that you can easily become too aggressive toward the ends of the blank, so I generally minimize the time I spend toward the ends. This is where good lighting and a hand magnifier lens comes in handy. You can easily see when you have sanded out the scratches from the previous grit.

One last point about dry sanding, after you've sanded with the lathe turning, always stop the lathe and sand axially along the blank. This leaves the scratch marks from the current grit running along the length of the blank. Then when you switch to the next finer grit, sand with the lathe turning. It's a lot easier to get rid of the previous grit's scratch marks this way. (I've spent way too much time looking at scratch marks under magnification ).

 

[RichB]

I have found that pressure on the application pad with thin CA can make a big difference to the build up thickness. I use nothing but thin CA for almost all of my pens but I do not push hard on the pad.

 

[bradh]

Wet sanding removes more material than dry sanding. The water washes the material out of the pads and keeps them cutting longer.
I only sand dry. For the first two MM grits, I only sand along the axis with the lathe off. I don't start the lathe until the third pad (2400MM).
To clear the pads of grit after sanding, wipe the pad on a denim rag.

 

[plano_harry]

I agree with Tomas. 16 is my minimum for thin. ..

Good luck,
Harry

How thick is 12/16/20 coats? Is that drops and not coats? Is this layers?

Lynn (LL Woodworks) just ran a thread in this forum on that - for her, 8 coats thin = .0035 average thickness. So I am guessing at .007 on 16 coats.

That is coats, layers or separate applications. I put 2 drops of thin on a paper towel (to allow for some absorption). Wipe down and back with minimal pressure. That is one coat. Repeat 16 times, with accelerator after each group of four. I alternate the starting end with each group of four coats to balance the thickness.

 

[tomas]

I agree with Harry, but I only use medium CA for finishing and have never had a problem sanding through the finish.

Tomas

 

[miket in stl]

Sanding thru thin CA finish problems

Here is my $0.02 on the subject.

Blank prep: I sand my wood blanks to 1500. Wipe the wood with DNA. Apply BLO with 2000 wet/dry sandpaper, until I get a good slurry. Wipe off slurry.

CA finish: While it's certainly been a learning curve for me, I now use the foam pads instead of paper towels. I apply 1 coat of thin CA, and then accelerator. I then apply a coat of medium CA glue with the foam pad. I move the pad back and forth until I feel it grab. I then hit it with accelerator. I generally apply 6 or 7 coats of medium. I using less CA with the foam pad vs. paper towels and more CA transfers to the blank. Not sure how many drops I apply per coat, but I cut my foam pads to 0.75- 1.00" and lay down a thin (1/8" max) line from edge to edge. Once I complete a coat, I cut off the end of the foam I used, so each coat has a clean applicator.

I wait 24 hours for the glue to cure. I then start my sanding with 600 wet/dry. I always sand wet, to keep the temp down. I sand to 1200 with wet/dry and then all 9 grits of micro-mesh. I finish off the process with scratch remover applied with my fingers and buffing with rouge. Since I started this routine, I have not sanded thru a finish.

Mike