# Dull spots in a CA glue finish and sanding



## RussFairfield (Jan 5, 2010)

First an apology to many members. 
There have been a lot of questions in the past year about dull spots on CA glue. I think there are 2 of them right now. The usual response has been that they were caused by sanding through the finish into the bare wood. 

I have never seen this as being the cause because I never realized that anyone would be sanding that much. I have been giving more attention to the questions and their descriptions, and watching others turn and finish pens, for the past few months. I take back everything I said and thought - SOME PEOPLE REALLY ARE SANDING THAT MUCH.
They run the lathe too fast, use too coarse a sandpaper grit, use too much pressure on the sandpaper, and use it way too long. Yes, thay can and do remove all of the finish. 

Bare wood and CA glue can be sanded and polished to the same high gloss to where it is difficult to tell the difference. However, the bare wood will lose its gloss in a day or two of exposure to air and light. I already knew that, but I never considered that anyone could make it happen on the same piece of wood at the same time.

For what it's worth, here is how I sand CA glue, and I have never sanded through it unless I wanted to.

While it seems hard, fresh CA glue is quite soft and sands away easilly. I use 400-grit for sanding the cured glue, and only go back to 320 if there is a bad rough spot. I use fresh paper with each pen and I use just enough finger pressure to hold the paper to the wood. The sandpaper will cut by itself without a lot of pressure.

Be careful to not use too much finger pressure. Think "light". When you think you aren't using enough pressure, it is probably just right. I watched a guy bend the mandrel with pressure on the sandpaper. That was definitely too much.

I sand with the lathe spinning for noi more than 3 or 4 seconds to remove the high spots. 

Then I bring in a bright light so I can see the shiny spots that are dimpled in the surface, and sand with the 400-grit just until the shiny spots are gone and there is a smooth uniform matte surface, and stop. I only use 320-grit, and sparingly, when the shiny dimples are more than I can remove in a reasonable time (15-30 seconds) with the 400. 

It is now ready for the next coat, where I do the same thing again with 400-grit as many times as there coats of glue. 

The final coat is done with the same 400-grit to level it out. After that, there are many ways to get it to the high polish we want. After the 400, I go to 600 and do the same thing. Then I do it with 0000-steel wool, and 4000, 6000, 8000, and 12,000 Micro Mesh. 

Sometimes I use a little Renaissance wax on the 6k and 8k Micro Mesh, and sometimes I don't. Sometimes I think it improves the gloss after the 12,000, and sometimes I can't tell the difference, but I choose to do it anyway most of the time.


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## rjwolfe3 (Jan 5, 2010)

Russ how does one get dull spots in a CA/BLO finish when they don't sand? 

I use William Young's method that requires no sanding after and I noticed on some woods I have dull patches that show up a day or two later. I always wipe my blanks with acetone before putting the finish on.


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## jleiwig (Jan 5, 2010)

rjwolfe3 said:


> Russ how does one get dull spots in a CA/BLO finish when they don't sand?
> 
> I use William Young's method that requires no sanding after and I noticed on some woods I have dull patches that show up a day or two later. I always wipe my blanks with acetone before putting the finish on.


 
Do you let the acetone flash off completely and let the individual coats of CA dry in between? If not, the off-gassing can cause the dull spots your speaking of Rob.


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## rjwolfe3 (Jan 5, 2010)

Yep and yep.

I do it pretty much exactly like William's video except for the acetone.


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## Monty (Jan 5, 2010)

How long are you waiting after you let the acetone flash off? Acetone will, for lack of a better term, absorb water from the air and this can be as much as 5%. That takes a little longer to dry.


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## RussFairfield (Jan 5, 2010)

rjwolfe3 said:


> Russ how does one get dull spots in a CA/BLO finish when they don't sand?
> 
> I use William Young's method that requires no sanding after and I noticed on some woods I have dull patches that show up a day or two later. I always wipe my blanks with acetone before putting the finish on.



Personal opinion?  Most people use too much oil, but if you are having problems with only some species, I would suspect it is the oil already in the wood that is causing the problem.. 

It is important that the BLO under the CA finish be cured before putting the CA finish on top of it. That is and has always been the critical step for putting any finish on top of an oil - the oil has to be cured. Otherwise there will be adhesion problems or the oil will migrate into the finish and kill the gloss. The thinner places show up first, but it will eventually be a dull gloss everywhere. 

Natural oils in many species interfere with the curing of the BLO, so you are putting the CA finish over an uncured oil, unless the natural oils are removed from the surface. The problem is that there is always the risk that the oils will migrate to the surface and still kill the gloss in the finish. 

If you are wiping the surface with acetone, and still having problems with dull spots, I suspect that you aren't using enough Acetone. I know a guy who soaks the wood overnight, and he has the shiniest Cocobolo and Ebony I have ever seen.


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## dustmaker (Jan 5, 2010)

Russ, great post.  George and I were discussing in a previous thread that it is a good idea for all using a CA finish to understand just how much CA is being applied and what that translates to in terms of thickness.  I am an empirical type person and to me that means getting out the calipers, but most of the time I just feel my way through it.  I have tried to focus on building the skill of applying smooth layers, then less sanding is needed.  For me, a small piece of wax paper seems to get the job done.  I only use accelerant sparingly and then only every other layer.  I don't use BLO; seemed to cause more problems for me than it solved.  I only sand between layers when I goof up and get some bumps or rough spots and never go below 600 grit.  My thoughts are than if the layer is generally smooth there is nothing really to be gained by sanding.  Just my way, but in principle I think we agree: when sanding CA, less is more.


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## Noah (Jan 5, 2010)

Great post...I've never seen William's video, so I am ignorant about the use of acetone... can someone please give me a link to the video...?  I'd like to learn more about this method...

Here's what I do...Wax paper does the trick for me, it allows the CA to go on relatively smooth and then I use skew as a scraper to remove/smooth the top layer as needed...

Followed by sanding up to 12,000 Micro Mesh, then apply a product by DuPont called Rich Color Enhancement Pro... It makes the color pop and is applied like a friction polish... follow this with Mylands and Renaissance wax... no dull spots... I sometimes take it to the buffer and use Carnauba only...

Thanks
Ed


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## Daniel (Jan 5, 2010)

Russ first great post. Just to add to your description of the sanding. I can actually watch the high spots turn white while the lathe is turning. I can also see the low spots (shiney spots) also. I can get most of them without turning off the lathe to inspect. But I do my CA finish just as you describe her. it was how it was describe to me from the very beginning. I had trouble with sanding through when I first started out and quickly realized it was from starting with 220 grit paper. I also start with 400 and really hold my breath if I have to go to the 320. At least for me no coat of CA is going to survive 220 for very long if at all.
As for clouding. I have noticed it is a real problem with any of the dark oily woods. African Blackwood and Cocobolo are real monsters to get a good CA finish on. often requiring more than one attempt. I am also of the opinion that it is the oils int he wood causing the problem combined with the fact that dark wood seems to highlight any flaws.


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## Seer (Jan 5, 2010)

I just started using a method I learned from Colin at Kallenshan woods he showed me when I was there in Vegas.  He also put it on his website:
www.mysimplecafinish.com  and so far I have had great success as well as the learning curve which imho never stops curving


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## jttheclockman (Jan 5, 2010)

dustmaker said:


> Russ, great post. George and I were discussing in a previous thread that it is a good idea for all using a CA finish to understand just how much CA is being applied and what that translates to in terms of thickness. I am an empirical type person and to me that means getting out the calipers, but most of the time I just feel my way through it. I have tried to focus on building the skill of applying smooth layers, then less sanding is needed. For me, a small piece of wax paper seems to get the job done. I only use accelerant sparingly and then only every other layer. I don't use BLO; seemed to cause more problems for me than it solved. I only sand between layers when I goof up and get some bumps or rough spots and never go below 600 grit. My thoughts are than if the layer is generally smooth there is nothing really to be gained by sanding. Just my way, but in principle I think we agree: when sanding CA, less is more.


 


I think Frank said just about everything I was going to say and good job with that. 

I too follow some of these reports about dull spots and problems with CA finish. I am like Frank, I do not use blo because I still feel it ( not proven) breaks down the composition of CA. I am not convinced that there is not a set of problems that arise with the use of blo in the mixing of CA especially when using an exellerator. I too shoot for the smoothest layer I can get so there is virtually no sanding. My sanding comes when the CA has cured and then I go through the micromesh steps as if it were an acrylic pen. Never sanding more than a couple seconds and always going back and forth across the blank. Never letting the micromesh sit in one place. I feel if you have to start sanding with 400 grit paper you need to adjust your application method. I will alwys use thin as my base coat and sometimes I will hit that with some 1200 black automotive paper wet sanded to give that smooth touch and then layer from there. If using oily woods I always wipe the blank down with a towel wet with acetone. Let the lathe spin a few seconds and then start. 

As far as dull spots showing up later in the pen I feel that is the oil from the wood has escaped under the finish. Can this totally be preventive. I would say yes if you make sure the first coat seals the wood right after you wipe it down with acetone and let that dry properly. The first layer is the key. If you have to sand agin after the first layer make sure you apply a second first layer of CA (thin). Now treat this as your base coat and make sure it has cured before moving onto the top coat layers. Hey we spend the time to spin the blank why not take the time to do the finish instead of being in a hurry. That is why I do not understand the blo addition. Are we in that much of a hurry.??? Just a few of my thoughts.


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## RussFairfield (Jan 5, 2010)

Daniel, you eyes are a lot younger than mine. I need it not moving and a bright light.

As for sanding between coats. Except in the case of shellac and lacquer where a subsequent coat melts into the one under it, all layered finishes depend on a strong mechanical bond. That bond is improved if the gloss is removed from the surface of the coat that will be covered. CA glue does a pretty good job of sticking to itself, and that is the only reason we can get away with not breaking the gloss bewteen coats; but why not spend 10 seconds and make it stick even better. 

The other problem is that we cannot depend on covering up any imperfections with more finish. The opposite is true and the next coat will magnify everything on the surface rather than hide them. 3 coats without sanding and they are 3X larger.

I know that many claim they can lay out a perfect coat of a finish that needs no sanding. I cannot, so I also sand to make the surface smoother between coats, and finish the finish after the last coat.


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## RussFairfield (Jan 5, 2010)

John, imagine a slice of swiss cheese where all of the holes are filled with a tacky oil. On a microscopic scale, that is what a coat of CA glue looks like when we use oil and don't get all of it cured and covered, or removed. The more free oil, the more or larger the holes filled with oil.


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## mdburn_em (Jan 5, 2010)

Russ,
You should have seen me when I was first starting.  

I used to hold one of those 3m sanding sponges (thin ones) under the sandpaper so I could press as hard as I wanted without burning my finger.  Before using the sponge, I raised a blister or two.  

Looking back I think I was close to lifting the mini lathe with one finger.  *sigh*


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