Wet sanding wood?

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mgatten

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Probably a very dumb question, but they say the only thing dumber than a dumb question is the dumb guy who doesn't ask it.

I keep seeing mentions of wet sanding. I'm a newbie with only 8-10 pens under my belt, but I'm trying to learn as many techniques as possible. My first five pens were all dry sanded and micromeshed down to 12000 and then CA-finished. They all came out amazingly.

Then I decided to try wet sanding. Is this perhaps actually only for acrylics?

I've tried a few now, and no matter what I do, the wood grain raises up as the wood gets damp. That's to be expected, of course, but I figured the problem would go away as the grits continued getting smaller.

And it does, for a little while, but even going all the way down to 12000, the nice smooth wood gets fuzzy again after a short while. The only way I've found to save the pens is to let them dry and then start over with dry sanding. So the wet is doing nothing but wasting my time at the moment.

What am I missing? I'm sure this probably works great on acrylics, but do people do it with wood? If so, how do you get it to where the grain stops raising? And what is the advantage of it over dry sanding?

Marshall
 
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TonyL

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I did, what Monty does. Also, there are plenty of folks here that are delighted to answer any question. Enjoy your turning.
 

mark james

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As with Monty, I only "wet" sand with water on acrylics or similar - 2 hrs ago it was truestone/aluminum.

But... I do sand some wood blanks with walnut oil, linseed oil, etc... This is when I will usually leave a matte finish. There are many varieties available online.

It will be a matter of what you want the final appearance and feel to be.
 

Curly

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You can wet sand wood but not with water. You would use an oil like Boiled Linseed Oil (BLO) with the medium/finer grits to form a slurry to fill pores in the wood.

Warning! Warning Will Rogers! Spontaneous combustion can occur with sandpaper and rags with finishing oils on them so get them out of the shop and spread them to dry or submerge them in a bucket of water.
 

dogcatcher

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If I am turning wood and plan on finishing with Danish oil or teak oil I sometimes wet sand with either Danish oil or teak oil. As to acrylics I use automatic transmission fluid for my wetting agent whne wet sanding.
 

leehljp

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I rarely wet sand pen blanks. Some people do, some don't.

The professionals that don't - will have just as effective and beautiful of a finish as the professionals that do.

If it helps you, do it. However, a warning: in cooler weather such as around 75° and below, moisture in the wood can come to the surface under the finish (CA) and cause cloudiness. It does not always do that but it does it on occasion.
 

mark james

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You can wet sand wood but not with water. You would use an oil like Boiled Linseed Oil (BLO) with the medium/finer grits to form a slurry to fill pores in the wood.

Warning! Warning Will Rogers! Spontaneous combustion can occur with sandpaper and rags with finishing oils on them so get them out of the shop and spread them to dry or submerge them in a bucket of water.

Sorry Old Man... Will Rogers was a tad before "Will Robinson"... (Yes, I know what you meant, and we are probably close in age!) But yup, the rags will still ignite! :)
 

leehljp

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How did you get the CA to stick after you sanded to 12,000 ???

Do you know how they got rear view mirrors to stick on glass for 50 years? A type of CA/Super Glue or early on other glues. The smoothness of the material is not what prevents CA, paint and other things from sticking. There is a huge misunderstanding of what causes or prevents adherence - smoothness itself is not necessarily the cause.
 

PatrickR

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Mgatten - water on raw wood is only useful in raising the grain before applying a water borne finish, usually water is applied, allowed to dry and then sanded before applying the finish.
Sanding so fine before applying CA is unnecessary and impedes a good bond.
 

leehljp

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Mgatten - water on raw wood is only useful in raising the grain before applying a water borne finish, usually water is applied, allowed to dry and then sanded before applying the finish.
Sanding so fine before applying CA is unnecessary and impedes a good bond.

Fine Sanding does not impede bonding. Before sandpaper, hand sharpened hand scrapers were used to smooth wood on fine furniture. They were far better at smoothing wood than the sandpaper we use today. Besides wax finishes, they had other paint finishes that would adhere and in some cases, those finishes are still adhering.

There are several turners here who turn so fine that they do not need sandpaper. I do that when ever I can. The smoothness of a turned blank or bowl by a well sharpened scraper or skew will beat sandpaper every time. And - the finishes including CA stick just fine. Now on oily woods and green woods, it does well to take that into account, but it is not the smoothness that prevents it from sticking or adhering.

My wife has been on me for ages to get a drop of latex paint off of the top of a window pane on the outside. House last painted 30 years ago. Paint drop still on the glass, endured 108° heat in the summer (2012) and 0°F in the winter, and it is still there. It is not the smoothness that prevents finishes from sticking.
 
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ivel

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How did you get the CA to stick after you sanded to 12,000 ???

Do you know how they got rear view mirrors to stick on glass for 50 years? A type of CA/Super Glue or early on other glues. The smoothness of the material is not what prevents CA, paint and other things from sticking. There is a huge misunderstanding of what causes or prevents adherence - smoothness itself is not necessarily the cause.

The windshield isn't spinning at 500 rpms slinging the glue everywhere. :biggrin:
 

PatrickR

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Mgatten - water on raw wood is only useful in raising the grain before applying a water borne finish, usually water is applied, allowed to dry and then sanded before applying the finish.
Sanding so fine before applying CA is unnecessary and impedes a good bond.

Fine Sanding does not impede bonding. Before sandpaper, hand sharpened hand scrapers were used to smooth wood on fine furniture. They were far better at smoothing wood than the sandpaper we use today. Besides wax finishes, they had other paint finishes that would adhere and in some cases, those finishes are still adhering.

There are several turners here who turn so fine that they do not need sandpaper. I do that when ever I can. The smoothness of a turned blank or bowl by a well sharpened scraper or skew will beat sandpaper every time. And - the finishes including CA stick just fine. Now on oily woods and green woods, it does well to take that into account, but it is not the smoothness that prevents it from sticking or adhering.

My wife has been on me for ages to get a drop of latex paint off of the top of a window pane on the outside. House last painted 30 years ago. Paint drop still on the glass, endured 108° heat in the summer (2012) and 0°F in the winter, and it is still there. It is not the smoothness that prevents finishes from sticking.



Ok, could be with CA. It isn't paint. At minimum it is adding a lot of unnecessary work to sand and polish to that level and then have to do it again to the finish coat.
In the world of paint, scuff sanding is the accepted way of getting the best bond. I don't remember ever seeing directions on a can that didn't recommend it as a first step. I don't think one drop is a good indicator.
 

robutacion

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In my view and answering the original question from the OP "Is this perhaps actually only for acrylics? " in general terms wet sanding refers to the use of water and wet and dry sandpapers or micromesh pads, the used of some oils in conjunction with sanding is something very different, water on dry wood as finishing is not a good idea for reason other have explained already so yes, when you read "wet sanding" is generally a process associated with acrylics.

As for "general" adhesion to very smooth surfaces, the most common practice in any applications where multiple coats need to be applied (pens, cars, etc.), initial/first coat is always very thin, this normally results in a better adhesion to following coats, thin coats will penetrate better.

Windscreens and rear mirrors specialised glues are no different than most of the very heavy duty industrial products, I have seen products used in a multitude of industrial applications that are mind-boggling, the stuff we buy in stores cannot compare.

Cheers
George
 

leehljp

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Ok, could be with CA. It isn't paint. At minimum it is adding a lot of unnecessary work to sand and polish to that level and then have to do it again to the finish coat.
In the world of paint, scuff sanding is the accepted way of getting the best bond. I don't remember ever seeing directions on a can that didn't recommend it as a first step. I don't think one drop is a good indicator.
"It isn't paint", agree with that. However, that statement doesn't change anything. CA, thin or medium, soaks into the wood every bit as well as lacquer, poly, tung oil, etc.

Below are links to two pens done about 10+ years ago. Neither were never sanded before applying CA. And CA was well applied. Both pens in use today. They were segmented and of course segmented sanding causes sanding dust (from the brass or bloodwood or black or silver solder) to smear on the other woods. Only REAL solution for a perfect finish is to smooth it as much as possible through the turning process - which makes it smoother than it can get (with no sanding dust produced) with extra fine sandpaper.

http://www.penturners.org/photos/images/940/1_30_Pieces_of_Silver.jpg

http://www.penturners.org/photos/images/940/1_Baron_PenStripes.jpg

If you read up on cabinet scrapers you will find that they get much smoother finishes than sandpapers. Glues and paint finishes adhere every bit as well to that kind if wood preparation as it does to scruffed/sanded surfaces.

Yes, I have read the reports from people who said wood needs to be scruffed. But that is simply not true, especially with CA. I just had a discussion on another forum with an old timer on another forum that holds to "old" ways that has proven not true - even among some of the most trusted folks of his generation. That discussion was on sharpening lathe tools. He commented that one of his mentors taught him that no one needs to hone a well sharpened tool off of the grinder. A grinder was good enough. However, a fellow here sent me a paper of one of the best turners of the time who says absolutely one should HONE the tools after using a sharpener. EVERY tool should be honed.
THE POINT: One can find statements one way and statements another ways, but the "proof is in the pudding", so to say. CA sticks well on fine sanded and scraped wood without a problem.
 
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mgatten

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Thank you!

Thanks, everybody, for the great advice.

I'll definitely do away with the water sanding idea. (Though the BLO sanding for a matte finish sounds really interesting. I might try that this week.)

And maybe I'll spend a little less time sanding since even if adhesion is fine at 12000, clearly people are happy with results they get with less.

Marshall
 

monophoto

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Wet sanding is a very broad issue, and can mean a number of things:

1. Wet sanding of wood with water is sometimes done to get a smoother surface. Yes, it does raise the grain, but that's the point - raise the grain and then sand it smooth. There is the issue that you may need to allow the wood to dry before you can apply a final finish; alternatively, you can use DNA rather than water. It will also raise the grain, but it will evaporate far more rapidly.

2. A more common practice, especially with pens, is to sand to 400 or 600, apply a CA finish, and then wet-sand the cured CA using micromesh. In this situation, what you are sanding is actually the acrylic finish on the wood, not the wood itself. This can produce a very smooth, glass-like finish.

3. Wet sanding can also mean wet sanding wood using CA glue. This can be done to produce a smoother finish on open-grain woods such as oak - the sanding produces a slurry that fills the grain in the wood. Thin CA won't work well - it cures too quickly. Instead, you need a CA that cures slowly - medium or even thick. A potential issue with this approach is that the CA will seal the surface of the wood, and if it is confined to small areas of the piece, it can lead to a spotchy appearance if some other finish is later applied on top.

4. It is possible to wet sand using an oil finish - Danish oil, teak oil, etc. Again, the idea is to create a slurry that fills the grain. This approach tends to avoid the splotchiness of wet-sanding using CA. Some oil manufacturers (eg, Bush's) actually recommend applying the final coat of oil using a fine-grit abrasive.

5. Some turners (Carl Jacobson) use either mineral oil, or a mineral oil and wax combination to wet sand. Unlike the other forms of wet sanding, this technique seems to me to mainly be intended to minimize sanding dust although it does also enhance surface smoothness. It is probably best suited for utility turnings where you intend to apply a food-grade finish, but I think it can be problematic if you want to later apply a lacquer or oil finish.
 

jttheclockman

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Probably a very dumb question, but they say the only thing dumber than a dumb question is the dumb guy who doesn't ask it.

I keep seeing mentions of wet sanding. I'm a newbie with only 8-10 pens under my belt, but I'm trying to learn as many techniques as possible. My first five pens were all dry sanded and micromeshed down to 12000 and then CA-finished. They all came out amazingly.

Then I decided to try wet sanding. Is this perhaps actually only for acrylics?

I've tried a few now, and no matter what I do, the wood grain raises up as the wood gets damp. That's to be expected, of course, but I figured the problem would go away as the grits continued getting smaller.

And it does, for a little while, but even going all the way down to 12000, the nice smooth wood gets fuzzy again after a short while. The only way I've found to save the pens is to let them dry and then start over with dry sanding. So the wet is doing nothing but wasting my time at the moment.

What am I missing? I'm sure this probably works great on acrylics, but do people do it with wood? If so, how do you get it to where the grain stops raising? And what is the advantage of it over dry sanding?

Marshall

Marshall, what you have been reading about wet sanding applies to non wood products or wood pens with a finish of CA, poly, or lacquer on top. You wet sand to avoid sanding marks made from the sand paper or MM and also helps those devices to last longer. heat is always your enemy in finishing so wet sanding helps keep paper cool. This applys to acrylics too.

As far as sanding to such high grit before applying a finish is just not needed. Despite the above controversy about adhesion the reason is no need and waste of time. 400 ( at times I take to 600 grit) grit is a nice stopping off point with sandpaper as long as you sand with the grain to help eliminate sand swirls.

When wet sanding you can use water or at times I like to use Formby's lemon oil. Helps lubricate and helps with sanding swirls. Good luck.
 

Woodchipper

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I don't wet sand any wood. I sand with the lathe on low for the first grit. Then I sand with the grain with the rest of the different grits in the pack. I use calipers to monitor the diameter of the wood blank.
My father said- The only dumb question is the one not asked.
 
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