Foggy haze, or whitish blurr

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RussFairfield

Passed Away 2011
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There have been several recent questions about problems with fog, haze, whitish blurr, or no gloss in recent weeks.

My finishing experience is that 95% (revised 3/3/07) of the problems with haze, fog, whitish blurr, and lack of gloss in a finish are due to moisture in the wood and under the finish film. It is easy to have these problems whenever the wood isn't as dry as we thought it was. It happens frequently in the exotic woods that are encapsulated in a thick wax when we buy them. Even wood that was dry and at equilibrium moisture content in some tropical rain forest country will not be even close to equilibrium where we live, and that thick coating of wax has prevented it from getting there. Add to that, some of these hard tropical woods don't give up their moisture easilly.

This problem is more noticeable with a CA, Enduro, or plexiglass finish because they are less permeable to the passage of moisture vapor through them than anything else we can put on a piece of wood. The softer finishes let the moisture pass through them, These harder finishes don't, and the moisture is trapped under them.

Lou Metcalf gave us the solution several months ago - let the pen blank reach equilibrium moisture content in our shop BEFORE turning it into a pen. Removing the thick wax will help this happen faster. We are talking in terms of months for a dense wood after the wax has been removed.

We need to plan ahead and buy the exotic wood we want to turn next year, not what we want to turn tomorrow.
 
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Russ,
I had one fog on me today.I live in Florida so there is no lack of moisture or tempeature.This particular wood has been in my garage in storage for about five years, the last six months of which were exposed to the atmosphere in the garage. It surely was stabilized.The wood is Cocobolo.

I like to rub-in a little BLO after the initial sanding and just before finishing to give the grain a little pop.I don't do it on every pen, mostly just on darker woods. I'm beginning to believe this may also cause the fogging.It seems like the only time I experience fogging is when I treat the wood.

Do you think this may be my problem?

It very well could be moisture pickup from the humidity in the garage. If the blo isn't causing this, then I may have to start storing my wood in the house.
 
I may have been too strong when I said that 99% of the problems were moisture related. The real number is probably more like 95%.

What is the other 5%? Natural Oils in the wood, and there Cocobolo is right up there at the top of the most oily woods we use. The best finish for these species is lacquer because the natural oils are soluble in lacquer thinner.
 
I agree about the moisture. Some actually unknowingly introduce more water in the wood by wiping/cleaning their barrels with DNA after sanding! [:0]

I agree with Russ about letting the wood aclimate to your shop. When I can, I drill a few days early and let it sit in the shop before I glue the tube. When in a hurry...I try to microwave the drilled blanks a couple of cycles before gluing the tube. Works great so far.
 
Had this very thing happen to a very nice Blackwood cigar I turned several weeks ago. We did a show this weekend and as I was setting up our displays I noticed what looked like a smear of something on the upper barrel. Upon closer examination I saw it was under the finish, a whitish area. I know just what it was .....moisture, or in case of the Blackwood probably oils, so that pen goes back in the refinish pile ....lol. I may have to heed Russ and use Lacquer on oily woods. Did I mention it was a pretty pen....had both heartwood and sapwood....I bet it woulda sold [:D]
 
I have had the most "foggy" finishes on stabilized wood. I am of the opinion that one of the causes might be the fines trapped in the CA when sanding with a slurry to fill voids. The fines then absorb light rather than refect it.
 
Just a note. If the finish is Lacquer and it is foggy it may be the wax after finishing. I read both here in these forms and in Find Woodworking Magazine that soft waxes (like Renisance wax) have high amounts of solvents. The solvents will haze the wood. I know wait a week before any waxing and that seemed to cure that hazing problem for my lacquer. CA is another issue and Russ is the pro on that one. Actually he is the pro on lacquer also but I thought I would post anyways.
 
Another Factor: HEAT. A lot of heat from sanding can cause the moisture or oils to be released over an extended time of several minutes, even during the finishing, which can cause the mixing with the finish application process. The differences in wood type, densities etc react differently and release internal moisture at different rates - according to how much heat has been generated. In other words - I believe that is why one blank will cause fogging and another will not. Harder wood blanks will generally generate more heat as more pressure is applied to the blank during turning. The more heat, the more the chances that the moisture will be released into the finishing process.

I think if fogging is taking place, then make it a practice to let blanks at least cool down to room temp before adding the finish.

Thanks Russ, for your insights. I was en route to Japan when this was posted and missed it the first time around.
 
Ive come to the conclusion that is probaly not a bad idea to have things a bit overdry for most of the things we do... as long as the blank doesnt split or misbahave.

Some of the realy hard woods can keep their moisture content almost indefinitely unles you encourage them to let it go.

I've had quite a bit of sucess with the microwave.... going at it gently.... like half a dosen blanks on high 20 or 30 sec at a time and plenty of time to let them cool.

I also seem to think that CA isn't a crystal clear as i would like.
I think I get more light and life with a shelac/wax composite friction polish.
I must have a go with white shelac some time.

cheers
 
Has anyone tried silica-gel to absorb any moisture that is released after heating the blanks, like in a microwave? I have heated several different pen, and bowl, blanks in the microwave over and immediately covered them completely while really warm, almost hot, in a thick layer of silica-gel... let stand for several hours (over night is better) till cooled off. The silica-gel absorbs the moisture and then can be dried and reused over and over. So far no problems. [:D]
 
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