White spots

[Randy Simmons]

I have been having a problem with my finish lately.

I finish my pens with CA glue, and then micro mesh down to 12000 grit. however, when I stop the lathe to inspect my work, I notice some small white spots. Sometimes they are under the finish, and sometimes they are on top. I wet sand with the micro mesh, and seal the wood with thin CA beforehand.

This problem also seems to be totally random. It's not a specific type of wood, or how much medium CA I apply, or how much I sand wood itself. It may as well be accredited to the phases of the moon.

Is there some sort of secret trick during the finishing process, or do I have to do something beforehand? (Or do you pros just take a break from turning during the waxing gibbous or something?)

Thanks!

 

[Steve Busey]

Hey Randy,

Are you using CA accelerator? Sometimes too much accelerator will cause fogging or white spotting as the CA cures too fast. Just a little spritz is enough to start the curing process, and give it a minute or so to dry before your next coat of CA, and see if that makes a difference. (thin CA will cure faster than medium, which will cure faster than thick, so increase your wait time between coats as you move from thin to thick)

 

[Ruby pen turning]

If you are using thin, then using accelerator that may be the problem. I my opinion, thin CA and accelerator should not be used together.
Maybe your paper towel is sticking to the blank if that is what you are using.

 

[Jim Burr]

+1 on the above. If you use accelerator, spritz as Steve mentioned and do it from 2-3 feet away. Also may be some moisture getting in the mix.

 

[Drstrangefart]

I've found a few different causes. White/hazy spots deep in the finish are typically from too much accellerator/too close when spraying it. Sometimes it's a little moisture still in the wood. On the surface, it can be a bubble or divot in the surface that packs with sawdust, then the first/next pass on the CA seals it in and you have to turn again to get past it. I usually try to do the best I can with it, and I draw the line somewhere before I grab a hammer. I just put it in the UNFINISHED PROJECT box and head upstairs for a while.

 

[Robert111]

If you are using thin, then using accelerator that may be the problem. I my opinion, thin CA and accelerator should not be used together.
Maybe your paper towel is sticking to the blank if that is what you are using.

Well, I don't know, Brian. I use thin ca and accelerator and I don't get those white spots or white blushing. I also don't get "outgassing" that leaves a white deposit on metal, something also that others have mentioned . I know what you're talking about though because I have gotten them when I used medium ca and accelerator.

With the lathe off, I do 3 coats of thin ca with a folded paper towel, then spray accel., then spin the work at high speed and hold a piece of cloth against it to generate some heat. I repeat the process 5 times for a total of 15 coats.

I never wait after this--I just go ahead and sand and polish. Whole deal takes about 30-45 minutes, I'd say. Results are great.

 

[jthompson1995]

How old is your ca? I've found through experience that older ca can contribute to white spots as well. Any time I see them, I start using fresh ( from the back of the fridge and warmed to room temperature) ca and the spots magicly disappear.

My technique is different than yours. I sand to at least 400 grit, higher if needed, apply 2 coats of thin ca with the lathe running at 1100 rpm with paper towels, letting it dry a few moments between coats. Next comes 2 coats of thick ca with a spray of aerosol accelerator from about 4 feet away with the lathe spinning ( still at 1100 rpm). I then let it sit until dry and sand, starting with 1500 mm usually and going to 3600 mm. I have done this enough to get nice, smooth layers of ca so I don't need sand very much at all. After sanding I buff with beall tripoli and white diamond wheels. I get a very shiny, durable finish that only takes about 5 min. start to finish. My every day carry pen has been through the wash at least twice and is still shiny.

 

[Dave Turner]

Once I tried using accelerator from a spritzer spray bottle to save some money. I also developed the white clouding spots. I went back to the aerosol can accelerator (NCF brand from Woodcraft) and have never had that problem since. I think it's a combination of accelerator formulation and drop size that contributes to the problem.

MY CA FINISH TECHNIQUE
I use medium CA (Satellite City Super T brand). I quickly wipe on a 3-4mm size drop of CA with a folded paper towel piece (lathe at about 350 rpm). Then a quick spray with accelerator, followed by another application of CA. I don't wait at all between steps. I put on 12 coats of the CA in this fashion. Then I sand the CA finish flat with 400 grit Norton 3X sandpaper. I only sand until I get a nice flat surface. Any residual grooves are easy to see because of the white powder CA dust. Once it's flat, I go through the MicroMesh pads. I then finish up with a buffer and get a consistent glass smooth finish.

 

[KenV]

Different manufactures of CA use different processes with different "purity". There are also several different grades/types of accelerator.

One combination may work perfect under a set of conditions and another combination may cause problems.

Staying with the same brand/label tends to have less problem. I find best overall use with the "mild" accelerator or none at all.

 

[nativewooder]

Maybe it's wood leprosy!!

 

[wouldentu2?]

Possibly it is sanding dust from the CA.
It can get in the depressions in the wood that have not been totally filled before you started sanding.

 

[leehljp]

A search of "white spots" on this forum will reveal this problem to be in existant back at the beginning. It is not a "new" or "recent" problem. Fixing the problem is the same now as it was then. Prevention is the same also.

Fixing (simply put) is sanding back down or turning back down to the spots or to the wood and starting over.

Curing or preventing is variable and several suggestions have been made. Please bear in mind that there ususally is not a "single" prevention item, but combination of things for preventing. Thin, thick CA; Kind of Accelerator (they are NOT all the same); temp and humidity (in which changes also changes the outcome); Irregular application of CA (lumpy, not smooth, adding layers over roughly sanded layers trap things.

Combinations are what complicates the problem solving.

Another "white spot" related item but different is "white Streaks". Caused from course sanding scratches that trap air, sanding dust and moisture (humidity or accelerator moisture). This usually happened to me if I sanded down a thick CA layer before it "cured". It was hard but it had not cured. Turing it on the lathe while holding paper towel to it heated it up, a small dust partical (or sanding grit from the sandpaper) would heat up, melt and dig into the surrounding CA, causing a streak. Hard but uncured CA is prone to this.

 

[jzerger]

I had the same problem that showed up after several dozen pens. I was using Medium CA and switched to Thin CA (always after "cleaning" with DNA) and the problem disappeared. Doesn't seem to matter the wood I was using although the more porous the more obvious. I assume it was due to the temp and humidity that increased earlier this spring (as always) in NC as I just started CA finishing in January.
Best of Luck,
john