So this may be a Dumb CA question.....

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MatthewZS

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Although I've done quite a few CA finishes at this point I'm still fairly new to the process. As such I'm having an occasional issue that I can't pinpoint..... Depending on the piece I'm working on I'll put on 5 or 6 coats of CA + BLO, then MM when I'm done. In 8 out of 10 pieces it works brilliantly. However, on the other pieces when I'm completely done and looking at the finish it almost looks like I've maybe MMed all the way back thru the CA shell?the piece will still be pretty shiney but not AS shiney. If I test at it with my fingernail it seems like it MIGHT be bare wood but it's hard to ever says if it's bear wood or if the CA just didn't shine up as much........... The whole thing just becomes this foggy grey area. So my question is: in most people's experience is a typical CA finish going to be thin enough to be sanded away by correct MM useage or is this impossible? How thick is a 5-6 coat medium CA finish in milimeters? How much would one pass of MM take off in milimeters? Whats a good way to test and make sure that a particular questionable section of your blank got enough CA?

I realize BTW that I'm asking questions that could potentially have some very vague answers at best..... I'm not looking for precise math, just general rules of thumb.

Thanks all!!
 
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Too many variables to provide an accurate answer (pressure applied during application of CA, pressure during sanding, method of application, etc.). However, one of the biggest problems that people have with a CA finish is that they do not get enough of a CA build up on the pen and they end up sanding through the CA to bare wood in spots.
 
+1 for Stan.

Not enough coats of CA applied.
Try and do it without the BLO.
I sand each coat down with 0000 steel wool before applying the next coat.
Use a high quality CA, the fresher the better.

I have medium CA that is very thin, almost like water.
So i build up at least 15 coats and sometimes more before i start sanding.

Light, even pressure when sanding is key.

Also leaving the blank to cure for a day helps out a lot with the cloudiness.
Some CA takes longer to degas itself and this can cause cloudiness in the finish.

Also the type of wood can give you trouble.
Oily woods need to be rubbed down with Acetone before application of the CA.
I do this on all my wood pens, no matter what type of wood they are.
Better safe than sorry and have to redo it.

Hope some of this helps!

Andrew
 
One other thing to consider is the age of your CA. Older CA will not finish as nicely as newer CA and may cause what you're seeing. If your CA is over a few months old, try getting some new CA and see if that helps.

I buy larger bottles and leave them in the fridge for extended storage, decanting into very small bottles for everyday use so if it does go bad, it's only a small amount, not a big bottle.
 
MatthewZS said:
Although I've done quite a few CA finishes at this point I'm still fairly new to the process. As such I'm having an occasional issue that I can't pinpoint..... Depending on the piece I'm working on I'll put on 5 or 6 coats of CA + BLO, then MM when I'm done.
Click to expand...

I MM only with 7, 8, & 9 after CA/BLO. It polishes up the CA without removing it.

Sharon
 
I was begining to suspect that I just wasn't putting on enough and I've got some confirmation now. I also hadn't though about only using the finer portion of the MM range but that does make sense. I knew there where some vague areas in my question but I think you've all defeated the vagueness and given me some directions to go. Thank you all:)
 
I believe there are as many ways to produce a CA finish as there are turners. The best part of that is, they are all correct. If a finish is working for you it is right for you at that time. As experience (ie. recognizing a mistake when you make it again) proves there may be better way, seek it with all of your being grasshopper. If you use an accelerator and apply too much it can cause hazing or fogging but usually applying additional coats has solved the issue for me. I haven't tried it but I wonder if a craftsman with reliable measuring equipment could check the diameter of a turned, finished blank before and after applying a CA finish to determine the actual thickness of the coating. My guess is it is much thinner than we presume it to be, maybe a mil or two. My yard stick just doesn'r cut it for that kind of work. Any takers?
WB
 
MatthewZS said:
I was begining to suspect that I just wasn't putting on enough and I've got some confirmation now. I also hadn't though about only using the finer portion of the MM range but that does make sense. I knew there where some vague areas in my question but I think you've all defeated the vagueness and given me some directions to go. Thank you all:)
Click to expand...

I just did a pen in curly burly walnut that was very hard to finish with CA. Different parts of the wood accepted the finish differently and the finish was bumpy after six coats. I added six MORE coats, and still the surface was uneven, so I wet sanded it through all nine mm grits, and got a mottled but smooth finish. I then put on an aditional 6 coats and dry sanded with 7, 8, and 9 to polish it. I was very happy with the result, ( if not with the photography!)
burl.JPG
 
I have been working with some Burmese blackwood that has clouded on every piece but one. I know I'm not sanding through and I've been cleaning with acetone beforehand but it just keeps happening. I had this wood requested so I'm going to keep at it till I either figure it out or get lucky but after that this wood is going to be on my banned list. One this I was wondering is if it could be that in the final sanding I do before the CA if the paper is clogging and burnishing the wood in spots, preventing the CA from absorbing, it almost looks like it's not "wet" in those sections. I'm going to do some experiments with it over the weekend.

Wes
 
"Foggy grey" usually means that the wood wasn't as dry as you thought it was.

Another comon cause id that the wood is too hot from turning and sanding, and that means the moisture will change and the wood will shrink as it cools. Both can cause a CA finish to lose its gloss.

Weigh the finished piece of wood. Leave it until the finish has last its gloss; and weigh it again. If the weight has changed, you have the answer to your problem. Either a loss or gain in weight can be the problem.

If you don't have a scale, just let the pieces cool overnight before finishing, and that sould solve the problem. If not, it is something other than moisture.
 
I just re-read the post and wondered if this may help you; I always apply at least 2 coats of thin CA after sanding to 320 or finer. My theory is that it seals the wood and provides a "base coat" for the 3 to 5 coats of medium that follow. I then sand with 320 that has been used and become finer in grit both radially and longitudinally wiping between every sanding with a clean cloth. The last step before MM is 2 coats of thin. I use minimal accelerator on all CA coats. I've been doing this about 6 years now and it seems to make the dull spot prolem very minimal. I have the instructions for the process that I share with the folks at the Rockler demos I do and to those who take lessons from me in my shop. If interested PM me and I will forward.
 
Pardon me for chiming in since I am a mid level intermediate.

I find that using good old automotive rubbing compound then follow up with polishing compound after I work 5 to 10 coats of CA then at least sanding to 600 grit. Mind you I only have the lathe spinning at 800rpm.

Now I hope within the next month I will be getting a unique device to apply a finish that I use on the wood arrows I make... It's called an Eco-dipper using a product called Gasket Lacquer. You get this item of all places 3 Rivers Archery

Gasket Lacquer is one tough coating. I have shot the same dozen arrows that I made over 2 years ago, into foam targets, 3D, and soggy straw... even landed (more than I want to admit,) in the grass. It still holding strong.

Soon as I figure out the method, I will share it on here.
 
even landed (more than I want to admit,) in the grass. [/quote]

Got the arrow up on top of the rest did you? Been there, done that. Embarrasing when it is in a competition!

Sharon
 
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