Cracks in my CA Finish

[bcdezign]

I did this pen just a few months ago (4). Initially, I applied about 4-5 coats of thin CA and now the finish is marred by all these tiny little micro-cracks. Any clue as to what happened here? Other pens from around the same time are fine. The wood on this particular pen is Flame Box Elder.

 

[SDB777]

First of all welcome to the forum!!!


I'd have to say the wood wasn't dry, or at least not dry enough.
After you finished the pen the moisture content dropped......




Scott (re-finish.....) B

 

[1080Wayne]

Ditto Scott`s reply . Also , usually a good idea to let wood from another area adjust to your local temp/humidity conditions for a couple weeks .

 

[islandturner]

Initially, I applied about 4-5 coats of thin CA and now the finish is marred by all these tiny little micro-cracks. Any clue as to what happened here?

What if the wood was bone dry when turned; then absorbed moisture from the air as it reached equilibrium with it's new environment, and expanded a bit? Just a WAG...

 

[1080Wayne]

What if the wood was bone dry when turned; then absorbed moisture from the air as it reached equilibrium with it's new environment, and expanded a bit? Just a WAG...

Also possible , particularly if the CA coat was very thin and it was sanded to the point where some wood fibers were exposed , or the ends were not sealed with CA .

 

[bcdezign]

Interesting thoughts, I would have thought the wood would have been plenty dry as I had that piece of flame box elder for quite a while and it was already cut into a pen blank. But I guess one never knows for sure. When i turned it I saw no evidence of it being to dry or even too wet.

But I will take all your suggestions and see what I can do to prevent this in the future. Meanwhile, I'll disassemble this one and try again.

Thanks Guys

Brian

 

[thewishman]

Sealing the ends with CA will help with moisture problems. That way all of the exposed areas are covered.

 

[Parson]

Was the blank really hot when you applied the CA glue, ie, did you sand it a lot and then immediately hit it with CA?

Just pitching a random thought here.

 

[RussFairfield]

Your problem is most likely one of moisture content and growing wood. I agree with those who said that the wood was too dry, and that it expanded after it was finished and allowed to sit at room temperature for several months. The solution is to wait a couple days to give the moving wood a chance to settle down before applying a brittle finish like CA glue. If you can't wait, the simple solution is to use a more flexible finish than CA glue.

The problem can be as simple as the changing humidity in the air over the course of the several months. The difference between the pens being turned and finished in a heated room with a lower humidity and now you are looking at it the middle of the summer when the humidity is higher.

There are several reasons for your problem with growing wood. One is that wood storage can be a lower moisture than room air. Several months in a pile of dry wood can make it a lot dryer than it would have been it it were sitting out in room air. The other problem is that the heat from turning and sanding lowered the moisture content of the wood causing it to shrink more than it expanded from the heat. When finished while it was still warm and dry wood can crack a brittle finish like CA glue as it expands from cooling and absorbing moisture from the air.

Like all other finishes, CA glue will allow moisture to enter and leave the wood; the only difference is that it is slower than other finishes. Most other finishes are also softer and can take a bit of stretching as the wood moves. Only an acrylic plastic will not allow moisture to pass through it, and that can cause other problems.

A CA finish is very brittle and it can take some of the compression as the wood shrinks as it loses moisture, but cannot at all be stretched as the wood expands. Shrinking wood is more likely to show cloudy spots because the wood shrinking under the CA finish can break loose from the finish. Any expansion or movement as the wood returns expands as it returns to equilibrium with the atmosphere will make the brittle CA finish crack.

 

[larryc]

An answer to an unasked question!

I have made a couple of the postage stamp pens and have noticed the CA coating has cracked after a time. I now realize (after reading this thread) that I'm not letting the unfinished pen dry enough after applying the decoupage stamps and mod podge.
Has anybody determined how long the competed pen needs to dry before applying CA?
How about microwave drying?

 

[atomic ray]

When ever I have used the microwave to reduce the water content in my wood I found that it causes micro expansions, cracks.

I would dry with direct sunlight or a slow bake if you can.

I am curious what others who do not have year round miserable heat and sunlight to work with :biggrin:

 

[TallTurner]

I wouldn't suggest putting a metal tube pen in a microwave... metal and microwaves don't mix... if indeed that was what you were thinking. But I dry stuff in my toaster oven all the time. Just a thought.

 

[PJVitkus]

Interesting discussion, any insights on using CA interest me.

A few questions.

What is growing wood?

When you ask about how long to wait to allowing a completed pen to dry before you apply CA, are you talking about letting dry a turned and sanded barrel to which you have applied something like boiled linseed oil, before applying CA? Or?

I work primarily with wood that I have harvested, whose moisture content I measure before turning the wood. So far this has produced predictable results. Do you all use a device for measuring wood moisture content before turning the wood? Or is this not usually part of the process when it comes to turning pre-cut blanks?

Phil


I say predictable but not always desirable since when I craft pens for others using their wood that I know is way too dry (I'm not set up for stabilizing wood yet; and sometimes others want a pen from just their wood), I risk and even invite cracking somewhere in the process.