Stickfast CA finish crazing, carckleing

[MacG]

Greetings All,

I made two seam ripper kits using a stick of purple heart. I finished them both and put them in my computer case for when I would run into my nieces for whom I had made them. Last week I pulled them both out and on one the finish had crazed like crackle glass and the other did not. Smae stick of wood same finish. Maybe different application of finish as I cannot be sure if I put the CA and accelerator on in the same order - that is my only variable unaccounted for. Additionally I just noticed that a flashlight sleeve I made out of some anonymous wood from Rockler also has crazed a bit but I dropped it a while ago...

Does it matter which order you put on the finish? Does it crackle due to wood drying out?

Thanks!

 

[alphageek]

Welcome to IAP... you've asked a question thats very tough to answer.

CA finishes can be tricky. It might have to due to a lot of things... It could have been the amount of CA or accelerator. You are probably going to get 50 different answers to your question.

Myself, I don't use accellerator at all when I do CA finishes - I've had the best personal experience with the combination of CA and BLO (boiled linseed oil).

 

[MacG]

Welcome to IAP... you've asked a question thats very tough to answer.

CA finishes can be tricky. It might have to due to a lot of things... It could have been the amount of CA or accelerator. You are probably going to get 50 different answers to your question.

Myself, I don't use accellerator at all when I do CA finishes - I've had the best personal experience with the combination of CA and BLO (boiled linseed oil).

Well at least my question is not a FAQ It is said that there is wisdom in much counsel, OTOH if that's all you do is get counsel...What can I tell ya?
Always looking for the best and fastest finish but appears that the old adage is true here too "Fast, Cheap, Quality: Pick two."

Frustrating to see it crackle though. Looking forward to the many replies

 

[edstreet]

There are only a few handful of causes that would show this behavior. It's a very common problem and has been addressed a good number of times. I have documented this problem that I was approached with maybe 1-2 months ago. In the archives under terms such as "shattered glass" you will see it is a very hot topic on debates and bickering.

 

[jsolie]

Were they finished on the same day? I'm wondering if there might be a temperature / humidity thing going on.

I haven't had a CA finish crack like that...yet. I tend to use StickFast thin CA with a very quick spritz of the StickFast aerosol accelerator maybe every 5 or 6 coats. Sometimes I'll spray a little accelerator onto a paper towel and wipe down the blanks before applying any CA.

 

[keithbyrd]

I have had that happen with too much CA, too much accellerator and too many coats. I now put on fewer coats and concentrate on the polishing.

 

[MacG]

I have had that happen with too much CA, too much accellerator and too many coats. I now put on fewer coats and concentrate on the polishing.

I was wondering if that was it. I made them about 3 months ago and I am sure I was pressed for time. I sometimes have difficulty getting even finisuh on bead like shapes. Too thin near the low points and I can sand through. I may have had that trouble with that one and got too much on the rest of the piece. I will clean it all off and retry later today/

Thanks all for your input and I will search shattered glass later to get caught up on my mayhem for the week

 

[edstreet]

What is really going on is this.


The inside next to the blank is undergoing a SLOW cure.
The outside of the finish (exposed air) is undergoing a FAST cure.

The inside cures eventually over time and via torque it pulls on the skin of the CA and it shears and rips. The main problem here is the blank has loads of tension in it which is a bad thing.

The real underlying problem is the accelerator you are using contains acetone. With acetone buildup on the surface of the blank when you start your CA finish it can and will inhibit the cure process. The older the CA gets the longer it takes to fully polymerize. Over lapping these issues often results in this effect.

Long story short is using a low bloom and surface insensitive glue will bypass these problems, until then you will have to manage as best you can with conditions that can change drastically and yield uneven results.

 

[MacG]

What is really going on is this.


The inside next to the blank is undergoing a SLOW cure.
The outside of the finish (exposed air) is undergoing a FAST cure.

The inside cures eventually over time and via torque it pulls on the skin of the CA and it shears and rips. The main problem here is the blank has loads of tension in it which is a bad thing.

The real underlying problem is the accelerator you are using contains acetone. With acetone buildup on the surface of the blank when you start your CA finish it can and will inhibit the cure process. The older the CA gets the longer it takes to fully polymerize. Over lapping these issues often results in this effect.

Long story short is using a low bloom and surface insensitive glue will bypass these problems, until then you will have to manage as best you can with conditions that can change drastically and yield uneven results.

Thanks for your reply. You said "Long story short is using a low bloom and surface insensitive glue will bypass these problems" What is low bloom and surface insensitive mean, or which glues have characteristics?

Thanks,

 

[edstreet]

CA is polymerized by a PH shift. All CA on the market has a weak acid that keeps it in liquid form. When the PH balance shifts towards neutral it causes the polymerization to begin, the more rapid the shift the hotter the process is and the more brittle the end result is.

Surface insensitive types typically have more acid in them so it takes more of a PH shift to set them off. This can negate the surface conditions, the humidity in the air etc.


Low bloom.

Q: What is blooming?

A: Blooming or frosting is a phenomenon that occurs when cyanoacrylate monomer volatilizes off a part, reacts with moisture in the surrounding environment, and falls back down on the part leaving a white powdery residue behind.

In our case it shows up as white to cream colors inside the CA finish. It is not clear. There are several products out there that will fully cure with 3 seconds of a special low intensity light and never crack, bloom or the like.

 

[farmer]

CA

I make more billiard products then pens ,
my motors on my lathes run cool even if they are turned on for several hours .

I use stick fast medium............................................

I put on a healthy coat medium stick fast CA on and let it rotate in my lathe after 4 to 8 coats and normally about 5 hrs of rotating on the lathe and then I let the CA harden up for 24 hrs then I will polish it out.

If your CA gets old , it becomes stringy you finish will spider web or crack.

I don't use the accelerator............

Good luck.

 

[MacG]

CA is polymerized by a PH shift. All CA on the market has a weak acid that keeps it in liquid form. When the PH balance shifts towards neutral it causes the polymerization to begin, the more rapid the shift the hotter the process is and the more brittle the end result is.

Surface insensitive types typically have more acid in them so it takes more of a PH shift to set them off. This can negate the surface conditions, the humidity in the air etc.


Low bloom.

Q: What is blooming?

A: Blooming or frosting is a phenomenon that occurs when cyanoacrylate monomer volatilizes off a part, reacts with moisture in the surrounding environment, and falls back down on the part leaving a white powdery residue behind.

In our case it shows up as white to cream colors inside the CA finish. It is not clear. There are several products out there that will fully cure with 3 seconds of a special low intensity light and never crack, bloom or the like.

Thanks, any idea which glues have these characteristics?

 

[edstreet]

To get completely out of the problem arena you have to go into the 'light cured' realm of glues. Basically it's CA but it is cured via UV light, i.e. black light. The cost factor grossly goes up on these types as they are fairly new to the market and costly to make.

Aside from that I think the rule of thumb would be the more additives in the CA the higher the surface insensitive you get. Problem is not even the MSDS will list 100% of the ingredients used and many of the items are left out entirely.

 

[MacG]

To get completely out of the problem arena you have to go into the 'light cured' realm of glues. Basically it's CA but it is cured via UV light, i.e. black light. The cost factor grossly goes up on these types as they are fairly new to the market and costly to make.

Aside from that I think the rule of thumb would be the more additives in the CA the higher the surface insensitive you get. Problem is not even the MSDS will list 100% of the ingredients used and many of the items are left out entirely.

If that's true then the cost will go down as time goes on..Thanks for your input

 

[edstreet]

There is another interesting post somewhat paralleling to this one here.

www.penturners.org/forum/f18/does-your-ca-do-i-think-not-133393/