How many coats of CA?? Sanding finish problem

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philb

philb

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Hi,

Just trying my first few CA/Danish Oil finishes!

Trying to wok out how many coast of CA I need? I did two coast of CA and Oil, then MM down to 12000 and polished. But i think on the one barrel I seem to have sanded through the finish? But on the upper barrel its beautiful!

Is this just a case of being to aggressive with the MM and a bit trigger happy as it was my first attempt or would it be better to put more CA coats on so that I dont sand through.

Process was:

Wood MM to 12000
Danish Oil and CA x2
MM 1500 to 12000
Polymer Polish

cheers
 
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Phil, most people use a variety of different methods for CA finishing, so there is no one correct way. A lot depends on the type of wood, how far you sanded before starting the CA, and how smooth you can put on the CA.

The most common seems to be 2-3 coats of thin, followed by 3-4 coats of medium (or 2-3 coats of thick, then MM thru 12,000, trying to be careful and not sand thru CA, just leveling all the CA. If you do get in the habit of building-up thicker finishes, many have started turning their blanks down an extra .001-.003 to compensate for the extra finsh.

Do a search of CA finish and you will find lots of helps and information.

Rob
 
I turn about .005 under the hardware and build up 4 coats of medium CA. I then wet sand with 600 until the CA is flawless and then I sand thru the 9 steps of MM. I then polish with a mild auto compound and glaze (much like the Novus) and lastly a coat of Ren wax.

I do not use the BLO as I was never able to get enough CA to sand down flat and flawless. I now use straight CA and the Derlin strips to apply the CA.
 
It was medium CA i was using.

How the hell do you measure an extra .001 or .003 to take off. Surely thats getting a bit serious with the micrometer!

Sounds like i need to put another coat on and possible not sand so hard!
 
Very simple.. I use calipers on every kit and I sand on a slimline to say .327 with 220 grit and the 320/400 & MM will bring it down to say .326" / .325" where a slimline is normally .331"

Turning this way is serious, but easy and simple. I want my pens to be as perfectly flush to the hardware as I can get it. There is not one thing I hate more than feeling the edge of the blank or the hardware. I do not use a Mic, that is not easy on a pen blank, but a set of calipers can be bought for about $25.00 easy enough.

FWIW, human hair is about .001" so add 5 hairs on top of each other and you will see that on a pen. If I turn a wood blank to the bushings "assuming" that they were the proper size, my pen would be that much thicker once the CA finish is put on the pen.
 
Funny thing is that the slimline is one of the harder kits to do this with! The cheap flat center band even more so. On the flat band you could have this felt at the nib, and both ends at the center band and even a bit at the clip. Take a Jr. Statesman, there is very little on that kit that has a flowing hardware to wood other than the post end. The nib end on a twist pen can be the worst place to not have the size perfect. This is where you will feel it while the pen is held.

You might say, if it's more than a "hair" off, you can feel it! [:D]
 
I finish with tripoli instead of MM too. I have a good looking finish at that point but all my atempts at putting on a thick CA finish end up with what looks to me like an orang-peel affect. I wonder if it could have to do with the tripoli. Some of the hints on this string sound like they could also be the key though. I may skip tripoli and sand to a higher gloss then cure overnight with the CA. Does anyone use wood filler like Mylands after sanding and prior to CA or is that useless with CA?

Greg
 
Phil,

I do exactly as Lee (Firefyter) does. One of the first things that I learned from this forum was to use calipers on every pen, even if it is just a hobby for me. My calipers stay beside the lathe. I measure the blank end of the nib, the center rings and cap end and turn blanks down. Build up a layer of CA and sand down to the size. I can't start a pen unless I have the calipers in view.

To me, this was the greatest advice that I have taken from this forum and I have taken a lot from some talented folks here. This is not my advice but borrowed from those who have trudged down this path before. Thanks fellows!

For me, the point of making a pen is not to just make a pen, but to do it so it looks and feels good! And calipers are the tools for making sure this happens,

Two problems that many people overlook in CA finishes is 1. the build up of CA, or lack of it, and 2. sanding through problems. Flat spots occur when sanding through and that can be caused by the tail stock being just a smidgen too tight, the mandrel nut being a smidgen too tight, a bushing slightly out of round, a slightly bent mandrel, blank end not 100% square and a tad too much sanding pressure.

ANY of these problems can exist and have the bank turn seemingly smooth until sanding pressure is applied. At this point, out of round turning will be introduced to cause .004/.005 wobble or more. This will be unperceptible by feel but if two or three coats of thin CA are only .004 or .005 thick, and if more soaked in rather than building up at some points along the grain, then you will have sand through. Even 007/.008 layers can be sanded through easily if one or two of the above problems exist.
 
To emphasize a point Hank brought up, diferent woods will absorb more CA than others and absorbtion can be uneven along a single blank. I always put a couple coats of thin then sand smooth then start over again with a couple coats of thin then 2-5 of med or thick depending on the wood. Sometimes it takes 3 or 4 goes with the thin before I feel I have an even base of the thin and the blank has no bare spots.
 
Good point Phil, if I have a "soft" or "open grain" wood I do stabalize the wood and/or seal it with thin CA before I start to apply the final finish.

On more point is that some odd woods like burl can turn a bit off center if you tools are not razor sharp or you sand too much and too rough.
 
Some great advice, cheers lads

Think ill have to go and get some digital calipers! As my normal vernier ones are no where near that accurate or readable!

Thanks again!
 
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