CA finish going dull after assembly

[sschering]

I have one pen that has been driving me nuts..
I've re finished it twice and it keeps doing the same thing..

It's Madrone burl..

First time I finished it with 1 coat thin CA then 3 thick.. sanded up to 600 grit One end turned out dull so I thought maybe I'd snaded through the CA so I re applied 3 more coats thick CA then snaded it back to 600 and buffed with sipral and loose cotton wheels.

It was looking all glossy from end to end but when I went to assemble it half the pen was dull again..

2nd refinish I sanded it with 600 to an even sheen then put on 4 coats thin then buffed it to a high gloss.. I did a 2nd Purplehart at the same time.. same finish same CA..

The Purplehart kept it's gloss but the Burl was showing dull patches again 12 hours later..

What the heck is going on?

 

[Alzey]

The CA may be reacting with the oil in the burl. Try 1-2 coats of BLO prior to the CA. You can search the forum for CA clouding for other ideas.

 

[jttheclockman]

You say you sanded back to 600 grit??? What did you start with?? I bet you sanded through the CA. It does not take much. After you apply CA you should never have to go that low on the grit scale. Should be micromesh from there. Need to relook at your method. That is my opinion.

 

[Joe Burns]

It does sound like you may be sanding through as John suggested. I do the following.

Apply 10 - 15 coats of thin CA turning between centers without bushings.
Let dry and harden over night.
Cut loose the blank if any of the CA has overlapped onto the centers.
Mill the ends with a sanding mill on the lathe.
Put the blank back on the bushings
Wet sand the blank with Micro mesh starting with 1500 and finishing with 12,000.
Apply Hut's Ultra gloss
I finish with a two wheel buffer on the lathe.

Joe

 

[mpex]

Was having the same issue a week ago. I believe Joe and John are correct. I stepped the number of CA coats up and almost no sanding between layers unless some high spot really needs to be knocked down.
2 coats thin satellite city ca
8 coats sat city medium ca
Lightly sand on lathe turning at 1000 rpm w/600 grit
STOP LATHE AND SAND WITH THE GRAIN BY HAND UNTIL YOU SEE NO SHINY SPOTS
micro mesh wet for finish

I just ordered some buffing wheels and compound. Looking forward to seeing what that adds to the equation.

 

[leehljp]

Scott,

"Sand through" is the most common cause. However, there are a few root causes behind this. If using a mandrel and flex is introduced during turning; if the bushings are off center, (happens more than one would think); if the tail stock or the dead center/live center do not line up; of if using a non-60° live center in a mandrel - ALL of these can cause some "off center" turnings by about .005 to .007 or more. Then one side will get more sanding than the other and dull spots occur.

Sometimes, adding old BLO, or using some bad CA cause some dulling. But most of the time it is simply "sand through".

I use calipers and measure the turned, sanded and prepared blank before adding CA. Then I add CA and measure the build up. I also measure the CA as I sand it back down to size.

In doing this (using calipers) I know the size of the blank and the size of the nib/centerband/clip end. And, I know how much CA thickness I should add and build up to be able to sand back down to the level of the nib/CB/clip.

 

[CharlesJohnson]

I was making a lot of ridges when appling CA.Sanding every several coats for the ridges. Totaled a lot of coats.Sanded through on most of those times. What it took for the ridges. In other words, an application problem. Due to the advise so many on here were getting I finally tryed appling CA with a 1" strip of fun foam. Goes on a lot easyer. Not assorbed in the fun foam. Lot less wast. Not as much damage in the finish,ridges. I'm working on getting this to a much smoother last coat. Which is easyer with the smooth surface of the fun foam. I don't sand through near as much as I used to. I "like" progress.

 

[SteveG]

Just to add a point to what Hank said, which is a very good approach to develop a standardized method for finishing with CA. This process demands that your caliper measurements are both accurate and consistent. This comes from a reliable caliper and proper technique. You could check yourself by measuring a variety of blanks and other items, log the results and put that log away. then do it all over again making a fresh log. Comparing these two sets of results will tell you how precise and repeatable are your measurements. This self evaluation should be done in the same manner as you do when turning, ie. is the piece mounted on the lathe when you measure or do you pull it off to get a more accurate measurement. You get the idea. Improving our techniques makes us better pen turners. Happy turning...and finishing.
Steve

 

[Dalepenkala]

I was making a lot of ridges when appling CA.Sanding every several coats for the ridges. Totaled a lot of coats.Sanded through on most of those times. What it took for the ridges. In other words, an application problem. Due to the advise so many on here were getting I finally tryed appling CA with a 1" strip of fun foam. Goes on a lot easyer. Not assorbed in the fun foam. Lot less wast. Not as much damage in the finish,ridges. I'm working on getting this to a much smoother last coat. Which is easyer with the smooth surface of the fun foam. I don't sand through near as much as I used to. I "like" progress.

What is fun foam and where did you get it? Never heard of this.

 

[mpex]

I got mine at JoAnne Fabrics here in town:

Fibrecraft 2mm Foam Sheets - 12PK/Multi-Color : foam & foamies : kids & teachers :  Shop | Joann.com

 

[Lenny]

I often see it mentioned about the CA having ridges.... I'm not sure what exacly is being described ... is it really a problem at that stage of the process? Would successive coats not help to fill in the uneveness? At the final stage of applying the CA I will often have little bumps of CA especially at the ends, and use George's technique of carefully cleaning it up with a skew.

Isn't the idea to get sufficient build up so that once it is sanded (and for me this means MM pads not sandpaper) we have enough thickness that we won't sand through.

I just wonder if the ridges I keep hearing about are bad enoough they will cause a problem once the full process has been completed.

 

[Dalepenkala]

Thanks Moishe! Interesting!

 

[carpblaster]

I don"t usualy have as much sanding now that i use the foam,its slicker wastes less CA,and i believe it comes out better