HELP! CA Finish Woes

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PatriotPensPlus

PatriotPensPlus

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Joined
Apr 23, 2024
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Missouri
During assembly, after I pressed on the end piece, I noticed the CA finish developed what looks like an air pocket on the end. This has happened before on other pens and I had to sand off the CA and start over. What am I doing wrong? What can I do to prevent this? Is there a fix other than sanding and doing it over?
pen flaw.jpg
 
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I don't know if you are already doing this, but I found that sealing the ends with thin CA helps prevent this. Also use a bit less pressure towards the end of pressing parts together.

I seal the ends by wiping a soaked paper towel over the wood to keep spillage onto the outside, as well as doing it before the final polishing.
 
PatriotPensPlus said:
? What can I do to prevent this? Is there a fix other than sanding and doing it over?
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Prevention....Are you not trimming the blank up to the tube enough? If the blank is ever so slightly longer than the tube then I can see this happening.
I use a belt sander with a T-square and machinist vice to mount a center punch the diameter of the ID of the tube and sand the glued blank until I just get shine from the tube. Yes, this shortens the assembly but, only as much as you take off from the sanding. I've been doing this way for long enough I can hear the difference once I touch the tube to the sander belt.
Even when I was using the barrel trimmer (router bit type thing) I would trim until I saw the shininess of the end of the tube. That way I know the blank and the tube are the same length.

Fix....If it is an 'air pocket' (I imagine it is more than just that as the CA has loosened and possibly cracked) then deconstruct that end of the pen and try to wick some thin CA in under the air pocket. what have you got to lose? If it doesn't work you still will need to re-sand and reapply coating.
 
In addition to the suggestions above, make sure you clean the wood with DNA very thoroughly before applying the CA and begin with a super thin.

Also, just a clarification on what @Drewby108 noted above, he is saying that after you reface the ends of the blank after applying the CA (sanding jig is the best way) that you seal the ends with thin CA applied with a shop towel.

When, in the process, is this happening? It would help to know that as well.
 
In addition to the other suggestions , make absolutely sure that there is zero buildup of CA or whatever glue was used , in the tube , and that no inner burr was made on the tube during end sanding . It is also extremely important to press the fitting in dead square to the tube .
 
Woodchipper said:
Sometimes I rub the end of the coated blank with fine sandpaper to eliminate any coating that might be longer than the blank. Lightly rub in a figure 8 pattern.
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Agree with @wouldentu2? that this seems like the right answer. Sometimes when applying a CA finish, a small amount may drip down and build up on the end of your tube where your metal components are going to be pressed into the tube. When the components are pressed against that CA buildup on the end of the tube, the pressure then causes the finish on your tube to "buckle" and it might chip out or simply bubble up, which is what it looks like happened to your blank.

If you lightly sand the end of the tubes after you have finished polishing them, it will remove any CA buildup on the end, and your metal components can press in flush with the wooden tube without pressing against your finish.
 
Actually the recommendations above are good in particular situations but there are other situations that the sanding, wicking and sealing do not help.

1. This happens on oily pens more than others because there is not enough good adhesion. As a result it is easy to cause the CA to lift off of the blank and air gets under it. Wiping Oily blanks with acetone or alcohol before CAing an letting them sit 30 minutes or an hour, then apply the CA for greater adhesion.

2. IF you have a thick coat of CA on the pen and also flowing onto the bushing, when you break the bushing away from the blank, that will cause it (CA) to lift away from the blank, and it happens even more so on oily blanks. Some people take a razor knife and score the blank at the joint of the blank and bushing. Make the score more slightly towards the bushing side so that it doesn't show up on the blank.

If you are familiar with TBC (Turning Between Centers) the bushings are taken off after turning and then the blank is finished without using bushings in TRUE TBC. This eliminates that situation where the bushings are glued to the blank and prevents the air/CA lifting away. (This situation is what brought TBC to this forum years ago.) I like using oily ebony wood and have used it off and on for almost 20 years. Since changing to TBC, I have not had a single one separate because there is no stress on the blank and bushing - since the bushing is not used. And no lifting of the CA off of the blank.

3. If there is any, ANY, ANY AT ALL dried/cured glue inside the tube, when you insert the pen fittings into the tube it will also cause this. Make sure the tube is totally clean of any and all glue before assembling.

AS to FIXING: Disassemble, put on the lathe and gently use a scraper or carbide insert to turn the CA off and start over. Once CA has lifted or is turned off in spots, it changes the color of some woods and looks different to a discerning eye. It is best to re-do the finishing process from the beginning. And doing it this way is very helpful in problem solving.
 
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Greetings from Nebraska.

From your picture, I think most of the responses are spot on. I used to have this happen to me a lot. It can be very frustrating to say the least. Even though the solutions have already been presented, I'm going to add to the pile by explaining what was causing my problem and the steps I took to resolve it.

Most of my issues like this were caused by water penetrating the ends of the blank during wet sanding with MicroMesh. Either water soaking into the wood or somehow getting between the blank and the CA finish.

Here is what I did to resolve the situation. (Some of these steps are already part of my regimen, but I will include them as well, just to be concise in the steps that I take.

After turning I replace the "Turning Bushings" with "Non-Stick, HDPE Cone Shaped Bushings". Then I clean the blank with compressed air followed by wiping it down with denatured alcohol. This insures that any surface oils from the wood or from my finger prints is removed - done to prevent anything from impairing the adhesion of the CA. I let the blank spin dry for a good minute or two (not letting all of the alcohol evaporate before starting to apply CA has caused other issues for me in the past).

I start with a couple of applications of thin CA, no activator/accelerator, so that the CA can soak into the top layers of the wood to provide good adhesion. This is followed by a few thin coats of medium CA with activator/accelerator to build up some thickness.

Next, I take the blank off of the ""Non-Stick" bushings and I lightly sand off the CA that has built up on the ends. Either rubbing the blank ends against sandpaper on a hard flat surface or in my case by taking them back to the Blank Squaring jig and the disc sander -- making an extremely light pass, just enough to remove any CA buildup.

Since removing the buildup also exposes the end of the blank, I then apply a few drops of thin CA to a folded piece of paper towel to use as a blotter/applicator and with it laying on a flat surface I lightly press the ends of the blanks onto the blotter, giving them a little twist to make sure the ends get covered with a light coat of CA. After a minute or so, I sometimes repeat this step just as insurance, to make sure that it has created a seal between the CA on the end and the CA on the rest of the blank.

To further help keeping water from penetrating the end, I mount the blanks back on the mandrel using the Turning Bushings to help mask off the ends and help keep from exposing the ends to water as much as I can. This also helps me keep from rounding the ends over when I am sanding.

Anyhow, modifying my regimen to include this end-sealing step has virtually eliminated this problem for me.

Best Regards,
Dave

PS Any CA left behind on HDPE Non-Stick bushings will dissolve in Acetone, so when I take them off I drop them in a 4-oz jar of Acetone that I keep on my workbench. After a while (or the next time I'm in the shop), I fish them out of the jar with a toothpick and let them dry off on a piece of paper towel before putting them away. I've been using the same set for 3 or 4 years since starting this and the are still in near-new condition.
 
so I've experienced this a time or two, or three....

Much like some of the others above it seems to come down to a small piece of CA somplace towards the end of the tube. I try to make sure there is no excess CA anyplace on the inside or end of the tube before I start turning. I'll use a little light sandpaper on a rod to polish the inside of the tub and/or what ever else may be needed to get rid of the glue if it's there. When I get done turning I will very lightly re-square the ends of the blank using my squaring jig and disc sander. Lastly I've gotten to where I use the minimum amount of pressure to press the components together when assembling to make sure I don't crack the CA also.

To answer your 2nd question, I'm not sure that there is another option beyond popping the pen apart and sanding back down to wood in order to reapply the finish to fix the pen in the photo.
 
As far as repairs go, the only thing I would consider trying (as I have done it before, but only for pens I intend on keeping for myself) is to see if some Ultra Thin CA, like GluBoost Green Label, to see if capillary action would cause it to wick in from the end enough to fill the gap. Of course if it didn't work I would resort, as you suggested, to sanding the finish all off and the re-applying. Good Luck. - Dave
 
Thanks everyone for all the replies and great advice. After reading all these comments, I think maybe I forgot to sand the ends after the CA finish and before the pressing parts. Or maybe water wicked into the wood during the wet sanding even though I use the non-stick bushings. I fixed the pen by sanding off the CA coating and used Ausie Oil to finish this one. It came out OK but I really like the gloss of a CA finish. In this photo, compare the letter opener that was finished with CA next to the fixed pen. I hope the customer likes them both.
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PatriotPensPlus said:
During assembly, after I pressed on the end piece, I noticed the CA finish developed what looks like an air pocket on the end. This has happened before on other pens and I had to sand off the CA and start over. What am I doing wrong? What can I do to prevent this? Is there a fix other than sanding and doing it over?
Click to expand...

Are you saturating the bare wood with a thin CA first? All of it, ends included? If you just put a "coat" of CA on the bare wood, this can happen. I have always tried to give the first coat or two of CA a chance to penetrate and seal into the wood grain. This took a while when I first started using the GluBoost Thin. I just let it air dry instead of using accelerator so that it had time to seep into the wood fibers, but since they released Ultra Thin, its become a breeze, as that stuff wicks into the wood really easily. You should also seal the end grain at the ends of the blank as well (I just use my disc sander and pen trimming jig to flatten that out when I am done...just a kiss till you barely hear it touch the metal of the brass tube.)

When the glue isn't just a coating ON TOP OF the wood, but fully penetrates into the wood, separation like that should be highly improbable if not impossible.
 
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