Misunderstanding Sanding

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leehljp

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I am often in disagreement in basic sanding techniques from different ones. So, here are some thoughts and examples:

SANDING FOR ADHERENCE PURPOSES:
1st misunderstanding, and I heard this from old timers of whom I valued their opinions: Wood needs to have a rough surface from sandpaper for finish to adhere.
But I have also learned . . . :
1. I have learned that CA can make rear view mirrors stick on smooth glass for 50 years.
2. I have learned that house paint can stay on paned glass until the wife makes the husband remove it 10 years later.
3. My aunt drove under the Golden Gate Bridge when they were painting it in the late 50's. A few drops of the paint dropped on the car and they kept the car for 10 years. The reddish paint stayed put.
4. The idea is that wood absorbs humidity, and the changes from up under - is what causes paint to separate, and the roughness is what allows some paint to adhere longer. This is why it is recommended that furniture be finished on both sides - to keep most furniture finish from separating. On pens, finish is different than on furniture and the smoothness of the wood is basically irrelevant to finish adhering. JohnT and a few others (me too) START sanding at nothing less 400 or more. The smoothness does not affect the finish adhering to the wood in these situations.

SANDING TO PREVENT SWIRLS:
Numerous times in the past year or so (and previously), the idea of stopping the lathe and sanding WITH THE GRAIN to prevent swirls is recommended. I have never had that problem, and tried to figure out why others have to do that to get a good swirl free finish.

Today, I was looking as some things on "Pinterest" and it dawned on me what some of the differences might be.

IF one must sand WITH the grain for it to NOT have swirls, could it be that the technique is missing something? Look at these two links below, then answer the question below:



So, which direction does one sand or rub to get that kind of smoothness on the surfaces of those two objectives when looked at from all directions?

The conclusion is that it does not matter the direction of sanding/rubbing if the proper techniques are used. Maybe we could learn something by watching some YouTubes on how these guys/ladies polish the castings.
 
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Alchemist

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Howdy! Interesting observations! I have spots of paint stuck to my patio for over 10 years. Porous material.

I thought that sanding with the grain after each grit is to prevent uneven finishes? Or is this what you mean by "swirls"?
I follow the grain after every sanding to make sure that there isn't too much cut into the wood and finishes.

I, too, start with 400 grit. Anything lower seems to be over-kill and really eats material.

Furniture always start with 120 and double the grit.
Tobacco pipes...same except I move into the higher grits and then micro meshes.

However, as my technique has been improving, so has the need to stop the lathe as often. Which, I find nice because I use a shopsmith and only have 3 belt driven speeds. That means I'm sanding at 1800-1875 rpm's.

Just my experience.

CA glue will adhere to almost anything... skin to skin is the fastest bonding I've ever seen! (Or experiences!!) [emoji23]



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leehljp

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Most of the time, people stop the lathe and sand with the grain to prevent (sanding) swirls around the blank. In most cases that I have read, it was done on the wood before finishing is added. It does make logical sense to do that, but in reality, doing away with low numbered sandpaper, and moving up to 12000 MM, or other fine SP will do away with swirls quicker and better IMO.

Sometimes, people's familiarity with flat work (furniture) sanding follows them into making pens. I think that is where people get the idea of 120 grit up to 400. Even 400 grit SP will leave circles in many cases. That is why super fine finishes are done by starting with at least 400 and often 600 SP.

For me, on most wood or acrylic, I use my scraper, and some use their skew to achieve a smoothness before sanding that is equal to 1000 or 2000 grit SP or better.

Your post made me realize that I did combine two different situations: Polish is done on top of finish, sanding on top of wood. One does not usually use polish on wood except if it has a wax finish.

But the actions are the same.

Oh and one other thing you mentioned - some people do get ridges built up in applying CA or other finishes. Thanks for bringing that up. Most of the time, the ridges are taken off by sanding on the lathe as it turns - in my observations of posts here.

Again, The direction of sanding for achieving a great finish (either on the wood or CA/other finish or acrylic blanks) is irrelevant if done with the techniques used in the links above.
 
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jttheclockman

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I followed this but I did not follow this.:) Could not be bother looking at what others do. I feel they are wrong. It does matter how you sand. First off lets step back a minute here and think about sanding furniture or other flat work What machine do you use??? A random orbital tool of some sort and why is that. The EYE does not lie. If you only sand with the lathe on you will get swirls no matter what grit paper you use. Your eye picks this up. If you stop the lathe and sand with the grain you created straight lines and your eye thinks its grain and not sand marks. So I always always always stop lathe and sand with blank . I can lay 2 pens next to each other of the same woods and you can see the difference. Now you get into burls and woods with wild grains than the swirl marks can blend in better. You hand sand furniture or flat work you always sand with the grain and not against it, why because you again will see the scratch marks. Use of MM what is that, basically sandpaper so again same rules apply in my opinion and will always stick with it.
 
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leehljp

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Well JohnT, can you see the swirls on the two links I mentioned above? So which way did they sand them? Can't see them, can you?

You have said repeatedly that you do not use a loupe. I do. I do not sand with the grain; with a loupe you cannot see the swirls on mine.
JohnT: I can lay 2 pens next to each other of the same woods and you can see the difference.
Maybe with yours - you can, but with mine and a loupe I can't. But for the most part, the subject is moot with me - as I do most finishing with the razor sharp scraper, leaving no need for sanding.
 

jttheclockman

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Well Hank we will have to agree to disagree. I only use a skew if I am segmenting different woods. But if doing one type of wood I will hit with 600 to 800 grit paper and then CA. I sand with a block as I have mentioned many times. And always sand with the grain. And no I do not use a loop because I feel that is a waste of time. The first time a person writes with a pen there will be scratches. If you can see with naked eye you have better eye site than me. I need reading glasses when doing close up work. Not interested in the links Hank. Others may find it interesting and your point maybe better received. I only jumped into this because you brought my name into it. :) So I thought I would explain my method. This is just me and the way I do things. I do scrollsawing so do alot of flat work and for that I use a Porta Cable block sander http://www.bing.com/images/search?v...293EB8&selectedIndex=0&FORM=IRPRST&ajaxhist=0
 

Sylvanite

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The purpose of the first grit of sanding is to remove the tool marks (and any surface damage). The purpose of each successive grit is to remove the scratch marks from the previous grit.

As long as one's sanding technique successfully removes all these marks without over-sanding, then it really doesn't matter what direction the sandpaper moved.

That said, I DO sand pens circumferentially with the lathe on and then longitudinally with the lathe off. Why? Because that makes it easier for me to see that I have indeed removed all the scratch marks from the previous grit. If I sanded in the same direction all the time, I would run the risk of under or over-sanding because it's easy to mistake a deep scratch for a shallow one. When the scratches are perpendicular, it's easier to see exactly when I've removed all the marks from the previous grit and it's time to move to the next.

Regards,
Eric
 

Mortalis

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Eric hit in on the head with these statements,
The purpose of the first grit of sanding is to remove the tool marks (and any surface damage). The purpose of each successive grit is to remove the scratch marks from the previous grit.

As long as one's sanding technique successfully removes all these marks without over-sanding, then it really doesn't matter what direction the sandpaper moved. "


I have a B&L zoom binocular microscope that I use for removing splinters ;) and checking the sanded surfaces of pens. I agree with Eric that unless you remove all the scratch marks from the previous coarser grit paper you will struggle/fight with unsatisfactory finish.
Once I have sanded to what I believe is enough of the grit I am currently using I will take the blank to my microscope and check it many ways against the light source to be sure that all the scratch marks are the same. If there are scratch marks that are deeper or wider than the majority of what is there, the blank goes back on the lathe and I continue with the grit I just used to remove those deeper wider scratches.
Sanding against the circumferential pattern helps to break up the pattern to the naked eye by making the light bounce/reflect differently.
 

jttheclockman

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Wow microscopes too. :):):):) So we have Loops, Magnifiers,microscopes, powerful reading glasses to attack those stubborn scratch marks. I guess bottom line is be satisfied with final product so that you can be proud to sell at the prices you do. Happy Sanding.
 

leehljp

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The purpose of the first grit of sanding is to remove the tool marks (and any surface damage). The purpose of each successive grit is to remove the scratch marks from the previous grit.
Regards,
Eric

Eric, I guess I have the OC disorder. I ran into a problem about 12 to 13 years ago in a situation with segments that sanding of ANY kind would result in lots of smearing like pencil led rubbed across a piece of paper. I spent an hour or two just thinking the situation over, then an hour so thinking how to accomplish the finishing without sanding. It involved and depended upon how SHARP my scraper was. (MY scraper end is shaped like a radius insert.) Then I spent an hour getting my table, grinder, scary sharp and honing items in a row. I gave as much time to the sharpening as I did in preparation. Then I tried it on the segment. WOW WOW WOW! Smoother than sanding! The radius scraper end (NOT round end) was superb. NO tool marks, smooth from end to end. Sanding with even 1000 grit would only rough it up, AND smear the segment parts.

I do sand on occasion, but it is to just do something different. Even then, I don't have tool marks that have to be sanded out. and then it is usually to sand to shape a curve that I can't accomplish with my radiused scraper. And like I said, I do NOT use grits that will leave deep scratches.

The first 2 or 3 responses to my post about not sanding were negative saying it could not be done, then a couple of old timer bowl turners came on and said "of course you can. That is not uncommon among good turners."

No sanding lengthwise on this one back in 2006 or so:

NO sanding on these one in 2009:

Sanding is generally NOT necessary with the right techniques. "The proof is in the pudding."

JohnT. The purpose of a loupe for me is not to see how well I sanded because I don't usually. The purpose is to see how well NOT sanding . . . does - with the right technique. "And the proof is in the pudding."
 

Alchemist

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The purpose of the first grit of sanding is to remove the tool marks (and any surface damage). The purpose of each successive grit is to remove the scratch marks from the previous grit.

As long as one's sanding technique successfully removes all these marks without over-sanding, then it really doesn't matter what direction the sandpaper moved.

That said, I DO sand pens circumferentially with the lathe on and then longitudinally with the lathe off. Why? Because that makes it easier for me to see that I have indeed removed all the scratch marks from the previous grit. If I sanded in the same direction all the time, I would run the risk of under or over-sanding because it's easy to mistake a deep scratch for a shallow one. When the scratches are perpendicular, it's easier to see exactly when I've removed all the marks from the previous grit and it's time to move to the next.

Regards,
Eric

I agree... this is how I sand as well.


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jttheclockman

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Hank again I agree when doing segment work I always just use skew and no sandpaper and then right to CA. But if doing a burl or one type wood color I put skew away and it is so quick to use a couple grits of paper. usually 600 and 800 No need to go higher. and then right to CA With using a skew it takes practice and you do need to be careful because one slip and alot of work is lost. You can not slip with sandpaper.:) Many ways to get to final end.
 

howsitwork

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Guys if it works for you .... do it.

Nothing wrong with trying new techniques, who knows you may like it!

I sand along grain with pure wood and often with hybrid but as yet don't get on with CA as a finish.I'm not knocking it or those who use it , but as yet I don't get the finish I want from it .So still experimenting and learning from you all.

Horses for courses and all that.

stay safe and let's all stay friends pleas!
 
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