CA Cracking

[dkrwoodturning]

I have used CA as a finish for a long time and just noticed with 3 of my stock pens have cracked and have a crazed pattern like china. All the other pens I have checked and are fine. If anyone may give me an idea as to why this is happening after years of using it. I haven't changed my process since starting to use CA. Many thanks in advance.
Cheers
Darren

 

[CREID]

Maybe a picture?
Curt

 

[jttheclockman]

Darren, you did not mention the material you used the CA on and I assume it is a wood of some kind and there may lie the problem. Some woods just are prone to crack a solid finish such as CA no matter what you do. It would be nice if you give us abit more info and maybe there is a fix and then again like I said maybe not. Sometimes storage of pens especially in extreme hot or cold situations is also a problem and can cause cracking.

 

[renowb]

I had one crack in the past but it was because I made a pen from a non dry piece of wood and I knew that when I made it.

 

[eldee]

I often wondered if a heavy CA finish was subject to crazing over time and under what conditions.

 

[dkrwoodturning]

The main culprits are a piece of spalted English Beech, Walnut and Cocobolo. Curt I have tried taking a photo but it doesn't show up. I inspect each pen under LED light and they are fine cracks that a normal buyer would not see in normal lighting conditions.

The pens were turned and finished in October last year, conditions when finished were dry and hot. I apply the CA while the lathe runs and do use the pump bottle accelerator to cure, not the aerosol variety.

JT, I am in Bundaberg and there was a lot of flooding around December for a couple of months and a lot of moisture in the air. My pens are stored in the cases they are sold in and packed into plastic tubs. whether it was due to this I don't know, but it was only 3 pens but I don't want the others to go the same way. If it is a more constant dry temperature control then that can be fixed.

Eldee, I have always thought that myself and only use thin CA as a finish, I know people that use 30 coats of thin CA and they have had no problem with the finish cracking. I am just at a loss as to why.

Cheers
Darren

 

[jttheclockman]

Darren you mention 3 very different types of woods in relation to each other. You mention an oily wood to a very dense wood to a very fine wood.

My questions continue. Have you made other pens from these type of woods and in particular these 3 same pieces of woods???? If so have there been these same problems???

Did you apply the CA in the same manner as before??? Are these woods completely dry that you know of thus leading to the first ????

The Cocobolo which is the oilyest of the woods mentioned can give all kinds of finishing problems any time to anyone. This wood needs to be dry and cleaned with acetone before even attempting to put a finish on it. Then a light coat of thin CA and let to completely dry is the starting point.

Wood does not die. It will move with temp changes and humidity. CA is not a flexible finish thus cracks develop.

Lets wait till you answer the other questions before making any judgements.

 

[dkrwoodturning]

John, Have used the English Beech before with no problem. I soaked the Beech in DNA for a week when I cut the blanks. They were cut in summer when temps were 35 degrees C. They were then stacked and set aside to dry for almost a year. The Walnut and Cocobolo were one pieces and were received in a private swap with a friend here in the States. They were pre-cut and the shavings from drilling seemed dry to me.

It was evening when I applied the CA and it was a wet evening, I can remember that. I sand to 400 grit with the grain and then use a small stippling brush to remove the bulk of dust, I then use DNA to wipe down the blanks.

I did pick up one thing, the ends on the tubes I normally seal with CA and on these there is none. Would the moisture from wet sanding, be the cause of my problems. The Walnut and Cocobolo, it may be the variation in temperatures. Thank you for your input John, it has been a long time since I was on this sight as a newbie and got slashed and burnt. It is nice to see it has changed.

 

[hunter-27]

John, Have used the English Beech before with no problem. I soaked the Beech in DNA for a week when I cut the blanks. They were cut in summer when temps were 35 degrees C. They were then stacked and set aside to dry for almost a year. The Walnut and Cocobolo were one pieces and were received in a private swap with a friend here in the States. They were pre-cut and the shavings from drilling seemed dry to me.

It was evening when I applied the CA and it was a wet evening, I can remember that. I sand to 400 grit with the grain and then use a small stippling brush to remove the bulk of dust, I then use DNA to wipe down the blanks.

I did pick up one thing, the ends on the tubes I normally seal with CA and on these there is none. Would the moisture from wet sanding, be the cause of my problems. The Walnut and Cocobolo, it may be the variation in temperatures. Thank you for your input John, it has been a long time since I was on this sight as a newbie and got slashed and burnt. It is nice to see it has changed.

Yes!
I dry sand for this reason. Many will tell me I'm wrong. But so it goes, I'll continue to keep water out of my shop.:wink:

 

[jttheclockman]

John, Have used the English Beech before with no problem. I soaked the Beech in DNA for a week when I cut the blanks. They were cut in summer when temps were 35 degrees C. They were then stacked and set aside to dry for almost a year. The Walnut and Cocobolo were one pieces and were received in a private swap with a friend here in the States. They were pre-cut and the shavings from drilling seemed dry to me.

It was evening when I applied the CA and it was a wet evening, I can remember that. I sand to 400 grit with the grain and then use a small stippling brush to remove the bulk of dust, I then use DNA to wipe down the blanks.

I did pick up one thing, the ends on the tubes I normally seal with CA and on these there is none. Would the moisture from wet sanding, be the cause of my problems. The Walnut and Cocobolo, it may be the variation in temperatures. Thank you for your input John, it has been a long time since I was on this sight as a newbie and got slashed and burnt. It is nice to see it has changed.

Hello again Darren.

I will give you my thoughts really quickly because I have to go and won't be here again for awhile.


I am not sure anyone will be able to tell you exactly what went wrong and you will probably get ideas as to what others think. It could have been a combination of things and you may have to chalk it up to a learning experience. I do realize how frustrating it could be to spend all that time to finish a pen and get those results. Been there done that.

The introduction of denatured alchol is tricky when dealing with finishes because in essence you are adding water to the mix and if the blank is not completly dry again and each spiecies drys at different rates, when adding a solid hard finish such as CA and then hitting with an accelorator to speed that drying process can trap moisture underneath. Now when it does dry and movement of the wood itself happens you can have cracks develop. I never use DNA to clean a blank. May I suggest using the accelorator to do this or compressed air.

You mentioned the ends were not sealed and you wet sanded. I will say this I do this all the time and have no problems at all. First when wet sanding you are lubricating the sanding pad which makes it glide easier and thus does not create such big sanding marks. Remember when sanding out a finish you should only be doing a polishing sanding and not a forming sanding where you are removing lots of material. If you are doing that then you need to readjust your application methods. As far as the ends not getting sealed is not true. The ends will get some CA from the application to the main body of the blank. If water can get between the bushing and the blank when wet sanding it will not absorb into the ends because the CA has blocked it. You probably always have to do some trick to get the bushings off the blank unless you use special bushings. Now if you use those cone shaped bushings for your CA application then you always need to add some CA to the ends even if you do not wet sand.

The last thing I always question is the use of accleorator. To me this adds to many variables such as trapping moisture when doing you finishing in a high humidity condition. The use of accelorator hardens the top layer of the CA but the content underneath is still curing and now moisture has no chance of escaping. I prefer to let the CA dry naturally and if I want to speed things up I let the lathe spin at a slow rate till dry. I only use thin CA because I feel I can control it better and not have moisture trapped.

Like I said these are some of my thoughts and others may chime in and hopefully you get things figured out but not sure you will ever find the right answers. You can just try to prevent the obvious and hope for the best. As I said some woods are just destined to crack and good luck.

PS don't know anything about your last encounter with the forum. I am sure there were 2 sides to every story.

 

[MyronW]

It is possible to obtain anhydrous DNA and thereby eliminate the introduction of moisture during cleaning. I buy it when I am going to mix up a fresh batch of shellac.
Compressed air, unless it is properly dried, is chock-full of water vapor.
Before I apply CA, I very carefully blow off my blank with it. DOH! [facepalm] Maybe that explains some of my aggravation with the stuff!

This is why I am so fond of this forum. I am learning so much here about my own difficulties as I read each thread and consider each situation. Each day brings several new a ha! moments, and I can't wait to get out to the shop and give it a try.