DNA caused cloudiness in BLO/CA Finish???

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msteblay

msteblay

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Dec 24, 2009
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Location
Minnesota
Help,

I finished a walnut pen yesterday with 10 coats of BLO/CA finish. It looked perfect after the final coat. I let the CA finish cure overnight. This morning prior to MMing the final finish, I wiped the blank down with Denatured Alcohol to remove any dust and the walnut blank took on an immediate cloudiness (white spots) deep in the finish. The cloudiness did not disappear after the DNA was dry.

I decided to MM anyway and the cloudiness never went away until the final step where I used PlastX as the final polish. However, after assembly the cloudiness appeared again.

I thought I had read here than many people wipe their blanks with DNA to remove the dust so that was my plan before MMing.

I finished another pen in cherry not walnut and did not use DNA at all and didn't worry about removing the dust between MM grits. That pen appears to have no cloudiness at all.

Procedure:
1. Turned pen down to bushings
2. Sanded through all MM grits
3. Wiped down with DNA to remove dust
4. 10 coats BLO/CA (very nice finish)
5. Let dry overnight
6. Wiped down with DNA to remove any overnight dust (this is when the cloudiness showed up)
7. Sanded through all MM grits
8. Polished with PlastX (cloudiness disappeared at this point)
9. Assembled pen parts
10. Wiped down with Renwax
11. About 10 minutes later the cloudiness reappeared

Did I screw up with using DNA after the BLO/CA finish??? I thought the blank would be sealed at this point.

Sorry I can't post a picture of the pen because my daughter was perfectly happy to receive the 'reject' and ran off with the pen.
 
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Walnut has large pores . My best guess would be that they were not all filled by the CA/BLO , thus allowing entry of the alcohol in to the wood . I don`t know what would happen at the point . Wood at 6% moisture would probably be okay , but under your RH conditions your wood might be nearer to 12 % . You might try dousing a blank with alcohol , and immediately following with thin CA , to see what happens .
 
Moisture in the wood causes a cloudy finish. That moisture was there because the wood wasn't as dry as you though it was, or you intruduced moisture with the Denatured Alcohol, and didn't give it sufficient time to evaporate.

You have to consider that Denatured Alcohol readilly absorbs water vapor from the air, and that can be as much as 20% or more if you live in a humid climate and the can has been opened for any length of time. When using DNA to clean the wood, you should be waiting from a couple hours to overnight before applying the finish. Otherwise, you are putting a finish on moist wood, and it make any finish cloudy. Many times you can get away with not waiting, but there is always the risk of what you are now seeing happen.

Now you can either sand the finish off the wood and allow the wood to dry, or you can wait for the moisture in the wood to leak through the finish and evaporate. All finishes are permeable to water vapor, but CA glue is the least permeable of anything you can out oin the wood short of Plexiglass. That means you will have to wait a long time, and there is still the risk that the moisture has permanently damaged the finish at the surface of the wood.

The best thing to do is sand it off and start over, and next time you use DNA let it evaporate for the same length of time as you would had you wetted the surface with water.
 
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Step 3 How much time from application of the DNA until Step 4?

Step 4... What went on first... BLO or CA?
:confused::confused::confused:
 
Step 3 to step 4 was about 5 minutes of drying time.

Step 4 was BLO first followed by CA and then each subsequent coat was CA drops on top of BLO (William O Young method). I know the concern about putting BLO on first and then CA but I have had good success with this method in the past. The BLO adds a nice color to the walnut grain.

The cloudiness did not appear until I wiped the fully cured BLO/CA finish down with DNA prior to sanding the BLO/CA finish (the finish had dried about 24 hours at that point).

Going forward, I will not use anything to wipe the sanding dust off the blank other than a dry paper towel or compressed air.
 
msteblay said:
Step 3 to step 4 was about 5 minutes of drying time.

Step 4 was BLO first followed by CA and then each subsequent coat was CA drops on top of BLO (William O Young method). I know the concern about putting BLO on first and then CA but I have had good success with this method in the past. The BLO adds a nice color to the walnut grain.

The cloudiness did not appear until I wiped the fully cured BLO/CA finish down with DNA prior to sanding the BLO/CA finish (the finish had dried about 24 hours at that point).

Going forward, I will not use anything to wipe the sanding dust off the blank other than a dry paper towel or compressed air.
Click to expand...

The problem was at step 4. You applied a Boiled Linseed Oil wood finish and failed to allow it to dry. So it clouded under the CA. You THOUGHT that you were applying a CA/BLO finish. But CA/BLO begins with CA followed by BLO not the reverse.

The BLO does not come into contact with the wood. It sits on top of the CA and lubricates it and speeds the curing. It has nothing to do with the wood below.

When you put BLO under the CA on the wood itself, it is no longer an accelerator and lubricant. It is a wood finish. And like any oil finish, it takes time to dry. BLO without driers in it can take several days to properly dry. Certainly it should sit at least overnight.

Next time, finish your wood in whatever way you wish (with proper drying) and then do your CA/BLO starting with application of the CA first followed by the BLO. Your problem will not reoccur.
:wink::wink::wink:
 
The problem could be the moisture content in the walnut. I've had the same thing happen on several ocassions with "wet" walnut. Now, whenever I work with walnut, I turn to size, apply a sanding sealer, let it dry overnight then lightly sand, then CA finish. That seems to have cured my walnut woes.
 
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