Ca finish

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eteska

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Joined
Oct 29, 2019
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261
Location
Wisconsin
Hey guys thought I was getting better at my ca finishing but today I am struggling. I cast my first burl and resin blank. It turned nicely but have finished sanded down and re finished the lower blank but still have a significant issue. Top barrel looks fine. Am I going to fast? 55-60 degrees in the shop could that be a problem? Any suggestions would be much appreciated!
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studioseven

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May 6, 2014
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793
Location
Wisconsin
From your picture, it looks as if you sanded down through the CA. I don't believe temperature contributed to this. As for speed, I always slow my lathe down to its slowest speed setting for applying the CA. Sanding and polishing I speed it back up but I know others like to sand at a slower speed. How many layers of CA did you apply, and what was your sanding technique? Try adding a few more layers of CA and try sanding less. I also recommend Gluboost. You don't need to apply very many of layers and little to no sanding needed beyond micromesh. Good luck and don't give up.

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TonyL

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Mar 9, 2014
Messages
8,902
Location
Georgia
I would also say sanded through. I don't know how much temp has to do with anything, but I do keep above 68 if applying CA.
 

magpens

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Feb 2, 2011
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15,913
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Canada
Don't give up. . It can take several years to "master" CA finishing. . Even then, there seems to always be some "unknown" that crops up again and again for no apparent reason, even tho' you think you have done everything "the same". . The CA is always "the master" !!

Temperature ? . I dunno. . I have done CA finishing successfully at 40 degrees F (my shop is in my unheated but closed in porch.
 

eteska

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Joined
Oct 29, 2019
Messages
261
Location
Wisconsin
Thx for the quick responses. I don't think that I sanded through. I did 2 coats of thin and 8 coats of medium (if I counted right). Phone camera is acting up but I will try for a better image when I get home. To me it looks like it's one of the first layers. Not the way I wanted to start the day I was going to try and tackle one of those tru stone blanks next.


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leehljp

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Joined
Feb 6, 2005
Messages
9,314
Location
Tunica, Mississippi,
Yes, another sand-through. Tell-tell sign is very shinny spots and very dull spots next to each other. Most people do not realize how thin the coats are when placed on the blank with paper towel. The layers are very thin. Not much build up as believed, even with 6 to 10 coats of thin, medium or thick - when applied with paper towel. Paper towel absorbs 75% or more and wipes more off than it leaves on. If the build up is a tad uneven or rough, then 1/2 or more will be sanded off to get down to an even layer.

This is a time to get a good set of calipers. Measure the blank at different points after it has been turned as much as you are going to turn it. Write those measurements down. Then apply the CA with paper towels (as most people do.) You will find that you are not getting as much build up as you would think, especially after you sand it.

The next problem to look at is this: In many cases, there will be more of the shine removed on one side than the other. If it is consistent in the dull spots rather than more to one side, then your mandrel is not a problem and your technique is good. IF it is more on one side than the other, then you are having a problem with the mandrel in some form. (Several possibilities in this case, all mandrel related.)

I don't think this is a factor in your case after seeing the picture, but yes, temperature does affect the finish, not so much on the shine, but the curing time and sometimes white spots or clouding - if high humidity is present.
 

eteska

Member
Joined
Oct 29, 2019
Messages
261
Location
Wisconsin
Just an up date. Closer inspection I'm now sure I sanded through the ca. I sanded it back down refinished and was a bit more careful sanding the ca and polish and I am happy with the results.

Thanks to all who replied. The support from this community is amazing!

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Woodchipper

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Joined
Mar 15, 2017
Messages
5,138
Location
Cleveland, TN
Don't give up. . It can take several years to "master" CA finishing. . Even then, there seems to always be some "unknown" that crops up again and again for no apparent reason, even tho' you think you have done everything "the same". . The CA is always "the master" !!

Temperature ? . I dunno. . I have done CA finishing successfully at 40 degrees F (my shop is in my unheated but closed in porch.
I should live that long! I don't even buy green bananas now.
 
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