Chem/ultrasonic cleanings

[ericcheng2005]

How often do you guys get your instruments chem/ultrasonic cleaned? Need to schedule this stuff on my calendar lol

[Elow]

Honestly, not that often. My whole job is ultrasonic cleaning instruments and they’re usually not that bad. I get mine done once a year only because it’s free. If you clean your slide at least twice a week and give your horn a good thorough bath with snakes and stuff you shouldn’t have any problems. When i buy a new horn i also get it ultrasonic cleaned but that’s about it. People pay way too much for something that takes literally 2 minutes.

Edit: If someone does it well, it can be well worth it. I guess i have never had this experience

[Elow]

That’s how i like to clean all our slides that come through. Makes them better every time

[brassmedic]

Just want to say: when I do an ultrasonic cleaning, it's hours, not minutes. But then I don't just throw it in the tank and rinse it off.

[Elow]

Just want to say: when I do an ultrasonic cleaning, it's hours, not minutes. But then I don't just throw it in the tank and rinse it off.

What’s your process? We take apart the horn, take any grease off, rinse it, then throw it in. Our machine only takes 2 minutes. Once it’s done we use the air compressor to get most of the water off then we hang all the parts up to dry. After it’s been hanging for a day we clean the slides with brasso on a wick and oil/lube everything up and make sure there’s no fingerprints or anything and clean the inside and outside of the case. I was mainly talking about just the machine part, the longest part for me is always the case. Those damn tuba cases can take hours to get all the paint scuffs off.

[Doug Elliott]

I guess it depends on the solution and how good a job you want to do. Brasso is pretty abrasive... I wouldn't use it at all but if you're going to use it I'd ultrasonic AFTER the Brasso to get it out. And 2 minutes wouldn't be nearly enough to accomplish anything.

[brassmedic]

My point is, people aren't paying for " literally 2 minutes in the tank". That's the easiest part, and I agree with Doug that it should be in longer than 2 minutes. But there's a whole lot of other stuff that needs to be done, and you touched on that. But also, chem cleaning tends to stain the brass a pink color and etch the surface , so when I do an ultrasonic cleaning I go through the whole instrument and brighten up all of the unlacquered surfaces, inside and out, so they look shiny. And chem cleaning can also mess up a slide if it's already very smooth. If I do need to chem clean the outer slide because it's corroded inside, I would then polish the insides of the tubes, and then of course clean it again. Then there's assembly/ disassembly, checking springs corks and pads and replacing if necessary, and valve alignment. I'm sure I'm leaving stuff out, but at any rate it's a great deal of work if you care to do a good job of it. Well worth the money.

[Elow]

I guess it depends on the solution and how good a job you want to do. Brasso is pretty abrasive... I wouldn't use it at all but if you're going to use it I'd ultrasonic AFTER the Brasso to get it out. And 2 minutes wouldn't be nearly enough to accomplish anything.

Interesting, i just do what i get told. At first they wanted me using scotch brite pads but i asked for something else. For the brasso, i mean i use it on the outside not inside. We use a green solution, pretty sure its simple green but could be wrong.

[brassmedic]

Here's a french horn I did. The parts do NOT come out of the tank looking shiny like that. It's actually more work than the cleaning itself to make them shiny like that. And if you were to look inside of the tubes they will also appear bright and shiny. Notice the valve levers and springs are off, because the acid will discolor steel. There are lots of details that need to be observed to do this correctly.

20200218_174744.jpg

[brassmedic]

I guess it depends on the solution and how good a job you want to do. Brasso is pretty abrasive... I wouldn't use it at all but if you're going to use it I'd ultrasonic AFTER the Brasso to get it out. And 2 minutes wouldn't be nearly enough to accomplish anything.

Interesting, i just do what i get told. At first they wanted me using scotch brite pads but i asked for something else. For the brasso, i mean i use it on the outside not inside. We use a green solution, pretty sure its simple green but could be wrong.

I like Simple Green. It does a good job. I will use the Scotch-Brite pad for a really badly corroded tube, but if it's a slide tube I would polish it after that because Scotch-Brite is pretty abrasive. I use buffing compound to polish the slide tubes.

[Elow]

Here's a french horn I did. The parts do NOT come out of the tank looking shiny like that. It's actually more work than the cleaning itself to make them shiny like that. And if you were to look inside of the tubes they will also appear bright and shiny. Notice the valve levers and springs are off, because the acid will discolor steel. There are lots of details that need to be observed to do this correctly.20200218_174744.jpg

Wow, most of the horns we clean are student horns so not many look that shiny. But for the newer horns, i would love for them to look like that. What do you do to get them like that?

[Elow]

Interesting, i just do what i get told. At first they wanted me using scotch brite pads but i asked for something else. For the brasso, i mean i use it on the outside not inside. We use a green solution, pretty sure its simple green but could be wrong.

I like Simple Green. It does a good job. I will use the Scotch-Brite pad for a really badly corroded tube, but if it's a slide tube I would polish it after that because Scotch-Brite is pretty abrasive. I use buffing compound to polish the slide tubes.

How do you get in the small spots? Or like on a trumpet 3rd valve tuning slide thats attached to the horn? The only time i buff stuff is if one of the techs did a ugly solder job

[harrisonreed]

I don't do ultra$onic cleaning on my horns. Maybe I should at some point, but the tubes and valves are easy to clean on my own. The only thing I don't know about is the inside of the tuning slide and bell, which changes color over years and years. I think it's oxidization, or corrosion. Does ultrasonic cleaning turn it back to normal? Should I care? I imagine once it takes on the patina, that's that and it won't corrode further much over time?

For the outside the Yamaha brass lacquer polish seems to really keep dirt from sticking and keeps everything shiny.

[brassmedic]

I like Simple Green. It does a good job. I will use the Scotch-Brite pad for a really badly corroded tube, but if it's a slide tube I would polish it after that because Scotch-Brite is pretty abrasive. I use buffing compound to polish the slide tubes.

How do you get in the small spots? Or like on a trumpet 3rd valve tuning slide thats attached to the horn? The only time i buff stuff is if one of the techs did a ugly solder job

Scratch brush with brass bristles with Simple Green. Sadly though, Ferrees and Allied both sold a goblet shaped scratch brush which goes on a bench motor that was really good for getting hard-to-reach places. Mine wore out, and and I found out that it is discontinued. if it's an impossible to reach place like the back of the third valve tube, I do it by hand with Scotch-Brite or 3M brown scratchpad. I don't usually buff the outside of the instrument either unless I'm cleaning up solder work or if I'm relacquering the instrument. I definitely never buff valves, that would round off the edges and it would leak. Scratch brushing is great for that because it doesn't remove a lot of metal

[Elow]

How do you get in the small spots? Or like on a trumpet 3rd valve tuning slide thats attached to the horn? The only time i buff stuff is if one of the techs did a ugly solder job

Scratch brush with brass bristles with Simple Green. Sadly though, Ferrees and Allied both sold a goblet shaped scratch brush which goes on a bench motor that was really good for getting hard-to-reach places. Mine wore out, and and I found out that it is discontinued. if it's an impossible to reach place like the back of the third valve tube, I do it by hand with Scotch-Brite or 3M brown scratchpad. I don't usually buff the outside of the instrument either unless I'm cleaning up solder work or if I'm relacquering the instrument. I definitely never buff valves, that would round off the edges and it would leak. Scratch brushing is great for that because it doesn't remove a lot of metal

Thanks, ill start using scotch brite pads for now on. https://www.ferreestoolsinc.com/product ... blet-brush it doesnt say that theyre out of stock. I have seem some in our shop so ill hunt those down tomorrow and test it out. Thanks for the knowledge

[Doug Elliott]

"Scratch brush" and ScotchBrite are two entirely different things. Scotchbrite comes in different grades. Which are you using? What color is it?

Ultrasonic has some advantages but it's no miracle cure. I don't have any experience doing whole instruments but I've been using ultrasonic tanks for 30+ years and I know what they're capable of, and not.

Elow, you should plan on learning the right way to things someday, from someone who knows... I don't think you're learning it there.

[brassmedic]

Doug, the scratch brush is a rotary brush that runs on a bench motor. I use the pads if it's something the brush can't reach. I have green Scotch Brite pads and I have brown 3M pads that are called "metal finishing pads". The brown ones are a bit more aggressive than the green ones. Steel wool works well too.

[Elow]

I have green scotch brite pads for the slides and i know we have some of those scratch brushes somewhere which ill use for now on. Being a repair tech would be a cool job, but i dont think i would want that to be my career. My love for playing is far greater than cleaning horns. Right now its just something that funds my collection. Quick question, i was under the impression that the scratch brush is for the insides of the slides, not the outer. Am i mistaken?

[Doug Elliott]

I would consider the green stuff too coarse an abrasive for brass. It's not sold for metalworking, it's found in grocery stores...
And yes the brown ones are even coarser.

[Elow]

I would consider the green stuff too coarse an abrasive for brass. It's not sold for metalworking, it's found in grocery stores...
And yes the brown ones are even coarser.

What color do you use?

[paulyg]

I would consider the green stuff too coarse an abrasive for brass. It's not sold for metalworking, it's found in grocery stores...
And yes the brown ones are even coarser.

I heard somewhere that the green scotch pads (like on a kitchen sponge) will take caked trombonetine off stockings, but not harm the chrome plating, as the plating is harder.

It's worked for me so far.

[BGuttman]

I would consider the green stuff too coarse an abrasive for brass. It's not sold for metalworking, it's found in grocery stores...
And yes the brown ones are even coarser.

What color do you use?

There are gray and white. I used to use the white to clean the metal parts on Coordiatographs (manual coordinate measuring machines). You don't want to remove too much metal from calibrated ways.

Scotch Brite pads are rated for git density. I know the green ones are 320 grit and the brown ones are 250 grit (US grit sizes -- European ratings are different). I think the white ones I used were 1200 grit.

I don't do ultra$onic cleaning on my horns. Maybe I should at some point, but the tubes and valves are easy to clean on my own. The only thing I don't know about is the inside of the tuning slide and bell, which changes color over years and years. I think it's oxidization, or corrosion. Does ultrasonic cleaning turn it back to normal? Should I care? I imagine once it takes on the patina, that's that and it won't corrode further much over time

Ultrasonic cleaning usually won't remove oxides or change the color under lacquer. If your lacquer is starting to lift an ultrasonic clean will move that along (i.e. remove more). Ultrasonic cleanings remove caked on dirts and loosen scale mostly.

EDIT: Here's a page from 3M on different Scotch Brite grades:
https://www.3m.com/3M/en_US/metalworkin ... hand-pads/

[WGWTR180]

Love reading this thread. Great to know how professionals work as opposed to amateurs. Now I know what questions to ask before I have my horns cleaned the next time.

[timothy42b]

EDIT: Here's a page from 3M on different Scotch Brite grades:
https://www.3m.com/3M/en_US/metalworkin ... hand-pads/

Those are listed as industrial hand-pads and made of silicon carbide.

I'm not sure they're the same kitchen scrub pad you can buy at Walmart or Target and are made of plastic.

[BGuttman]

EDIT: Here's a page from 3M on different Scotch Brite grades:
https://www.3m.com/3M/en_US/metalworkin ... hand-pads/

Those are listed as industrial hand-pads and made of silicon carbide.

I'm not sure they're the same kitchen scrub pad you can buy at Walmart or Target and are made of plastic.

My experience with green and brown pads is that the ones from industrial supply and the ones from my local lumber yard are exactly the same.

[Crazy4Tbone86]

Folks, we need to be careful here! People keep talking about Scotch Brite, which comes in some very aggressive grits. I want to emphasize that Brad Close (and he has clarified this) first mentioned scratch brushing, which is a completely different thing. Scratch brushing is not an abrasive pad. It is a type of buffing wheel that has medium-soft brass bristles. You do not put a buffing compound on a scratch brush wheel, thus it is designed to remove surface dirt and not metal (although the friction can certainly remove metal if used too much).

I DO NOT recommend using Scotch Brite on an inner slide! Scotch Brite can easily remove metal. If you use one of the aggressive grits and rub the wrong way, it could do serious damage to the chrome plating. If you want to use something non-chemical to remove lime scale from the inner slide, this is what I recommend:

1. Use the FINEST GRADE of steel wool, probably best to go with 000 or 0000 grade. Keep in mind that these grades of steel wool are so gentle that they can be used for polishing furniture between coatings of polyurethane.

2. Only rub up and down the inner slide (the same motion that the outer slide moves). If you use a circular motion, even a super fine grade steel wool can make striations in the chrome plating.

Caution! If you do not understand any of this, don't do it and leave the work to a tech. Using any kind of abrasive incorrectly on any moving surface of a brass instrument (slide, rotary valve, piston, tuning slide) can mess up things very quickly!

[Doug Elliott]

I use 7447 (light gray) and 7448 (dark red), although I actually rarely use them at all. I always thought the white was non-abrasive but I see it's extremely fine at 1200.
Different abrasives - S is silicon carbide, A is aluminum oxide.

I don't do instrument repair so I'm not sure what the best use of them would be. Scotchbrite has a different effect than a comparable grade of sandpaper, because it's flexible instead of flat. Steel wool has a still different effect, not really abrasive at all.

You have to consider hardness of the metal vs hardness of the abrasive, not just coarseness of the grit. Chrome is very hard but I think all of those abrasives are harder and can do damage even if you can't see it.

[Bonearzt]

Just my take on this.

I have use a UC in the very distant past, but don't have access to one now. Biggest worry is blowing through any red rot that may be starting!!

I use the Slime Away from Allied, but don't dip outer slides, I MAY occasionally suspend so that only the crook is submerged. Read somewhere that it might etch the interior of the outer tubes, not a good thing in my mind.
For inner tubes, I buff with a cotton buff and the white compound, again from Allied, and buff the stockings at a 45 deg angle and the remainder of the tubes lengthwise.
For tuning slide tubes, rotor bodies, pistons, etc., I use a bristle brush in a drill and a soapy pumice slurry for the insides and ports of pistons, andexteriors a scratch brush only with a soapy water solution, pistons again at a 45deg angle to the body with no abrasive. Picked this up from the engine world where they hone the cylinders to get the 45 deg markings for oil retention. Seems to work for me.
I will only use the maroon scotch brite pads on interior of tuning slides if they are heavily built up with deposits, and inside ferrules I'm going to solder.

Eric

[PaulT]

I was wondering where the "Blue" Scotch Brite pads I use to clean my glass stove top fit within the Scotch Pad family in terms of grit. I don't know where the chart below came from, but it is all over the web. According to his widely circulated chart (of unstated provenance) , the household blue pad is of a similar grit to the commercial white.

I don't know why a person would choose to go with a household blue pad over a commercial white pad, but from my use of both on things other than trombones, the blue pad is thinner and more flexible/malleable, which may translate to an advantage when used for delicate work on curved surfaces (such as a trombone slide).

Or it may not.

The chart:

This only applies to 3M some of the off brands use different colors.
3M Scotch Brite Nylon Pads:
7445 - White pad, called Light Duty Cleansing - (1000) 1200-1500 grit
7448 - Light Grey, called Ultra Fine Hand - (600-800) 800 grit.
6448 - Green (?), called Light Duty Hand Pad - (600) 600 grit
7447 - Maroon pad, called General Purpose Hand - (320-400) 320 grit
6444 - Brown pad, called Extra Duty Hand - (280-320) 240 grit
7446 - Dark Grey pad, called Blending Pad (180-220) 150 grit
7440 - Tan pad, called Heavy Duty Hand Pad - (120-150) 60(?)
Green Scotch Brite is available EVERYWHERE. It's 600 grit.
Blue Scotch-Brite is considered to be about 1000 grit.
(The value inside the parentheses is directly from 3M.)
3M Chart
Less Aggressive --------> More Aggressive
7445 7448 6448 7447 6444 7446 7440
Finer Finish --------> Coarser Finish

[Doug Elliott]

I have never seen the blue or green pads grit specified by 3M. No mention in that chart of whether each one is silicon carbide or aluminum oxide. For blue, if that's the ones bonded to a sponge I think they're non-abrasive. I haven't seen any other blue pads.

For engine cylinder honing they actually aim for 60 degrees and it's partly for oil retention and partly to break in the rings.

I'd be careful with the "soapy pumice slurry" (Lava soap?). I know that's a common thing to do but pumice is very coarse and I would chose something a lot finer.

[Bonearzt]

Doug, you're probably right on the 60deg angle....Been a while...

The pumice is just abrasive enough to cut the crud on the interior of tuning slides and valve ports. I don't use it to lap parts or brush out critical areas like outer slide tubes or inside valve casings.

[brassmedic]

I have green scotch brite pads for the slides and i know we have some of those scratch brushes somewhere which ill use for now on. Being a repair tech would be a cool job, but i dont think i would want that to be my career. My love for playing is far greater than cleaning horns. Right now its just something that funds my collection. Quick question, i was under the impression that the scratch brush is for the insides of the slides, not the outer. Am i mistaken?

They make them for inside and outside. https://www.ferreestoolsinc.com/product ... blet-brush The first pic is for inside, the second and third are for outside. They don't say the goblet brush (second picture) is discontinued, but when I ordered it, it was missing from the order when I received it. When I inquired about it they finally admitted that it's discontinued.

[brassmedic]

I do scratch brushing with raw brass parts such as valve cores , valve casings, tuning slide legs, etc. You can also clean the whole exterior of an instrument if it's unlacquered brass. It's not something I use for trombone hand slides.

[brassmedic]

And I think there has been some confusion about the use of scrub pads. I don't use them on valve casings or valve cores because they are abrasive. I would only use them to get a part I can't reach with a scratch brush. How else are you going to make that part shiny?

[brassmedic]

I use the Slime Away from Allied, but don't dip outer slides, I MAY occasionally suspend so that only the crook is submerged. Read somewhere that it might etch the interior of the outer tubes, not a good thing in my mind.

I also avoid chem cleaning the outer slide. It has been my experience that acid cleaning AND ultrasonic cleaning both etch the surface of the metal. If I chem clean an outer slide and try to use it without further polishing, the slide action is TERRIBLE. I'd be interested to see if anyone has a different experience.

Sometimes, though, a slide has been neglected for decades and there is so much corrosion inside that I haven't found any way to make it right other than chem cleaning and possibly even scrubbing out the tubes, and then polishing the inside of the tubes.

[Posaunus]

I use the Slime Away from Allied, but don't dip outer slides, I MAY occasionally suspend so that only the crook is submerged. Read somewhere that it might etch the interior of the outer tubes, not a good thing in my mind.

I also avoid chem cleaning the outer slide. It has been my experience that acid cleaning AND ultrasonic cleaning both etch the surface of the metal. If I chem clean an outer slide and try to use it without further polishing, the slide action is TERRIBLE. I'd be interested to see if anyone has a different experience.

As part of my (ir)regular trombone maintenance program, I just had 3 trombones (that I had purchased used) serviced by a top trombone tech. One was relatively new (<10 years), the other two were significantly older (>40 years) with interior slide deposits that did not disappear after my warm water bath & snaking with Dawn. The service included chemical (mild acid, I think) cleaning of both inner and outer slides (soaked for 15-20 minutes, I believe), followed by thorough tapwater flush & rinse, then interior tube polishing (perhaps some polishing compound, followed by swabbing with lacquer thinner – but I could be wrong). Of course all 3 slides were also straightened and realigned. All slides now perform perfectly - perhaps better than new. They look great (no discoloration, pitting, visual defects), and are a delight to play. I would not hesitate to do this again if I purchase another used trombone.

[Elow]

I talked to one of the older techs, and he said he uses buffing compound on a wick for some of the nicer horns.

[Crazy4Tbone86]

I use Feree's Z19 Lime and Scale Remover in my acid tank. I am pretty sure it is the same chemicals as Eric's tank..... he said he uses the Allied Slime-Away. From what I have been told, these powders that are mixed with water are sulfamic acid. Sulfamic acid is in the sulfer family (you chemists can go to town with this) and it is used commonly in the industrial world to remove lime and scale from sinks, tubs, kitchen equipment, etc....

Chemical tanks are mixed to the liking of the technician. I worked in a shop for years that had an extremely strong mix that would remove the hair from your arms if you held your hand in it too long.....at least it felt that way! I hated having the acid tank that strong! They wanted the acid to be very strong and efficient because their goal was to have the lime and scale removed in about 4 to 5 minutes. If you left the instrument in the tank a couple of minutes too long, the copper that was dissolved in the acid would attach to the raw brass and make those parts red. It created more work for the techs because we spent so much time polishing the copper layer off!

When I set up my shop, I mixed the acid so that I can place the instruments in it for 20-25 minutes, sometimes longer if needed. I don't need to worry about getting the timing just perfect. In some ways, having the weaker acid tank saves me time because I almost never need to remove any copper build-up! I use my acid on outer slides and have ZERO PROBLEMS with etching. My customers have told me their slides work perfectly and they keep coming back. Again....I want to emphasize that my acid tank is probably much weaker than the average shop. I also only do tech work on a part-time basis, so I am not pressured to crank out repairs quickly on a strict time line.

I use a pumice soap slurry for inside tubings as well. It actually works very well and becomes a finer grit as you work with it. If you place the slurry inside a tuning slide and only scrub with a brush for a few seconds, you might see some faint scratch marks. However, if you scrub for two or three minutes, the pumice breaks down to a much finer grit and puts a high-gloss polish on the metal. With a little time, the pumice soap and water mixture will produce a mirror finish on the inside of tubing.

Any abrasive will become a finer grit with use. If you start with a 220-grit piece of emery cloth and use it long enough, it will eventually become the equivalent of a 600 or 700 grit. The friction breaks down the grit.

[Crazy4Tbone86]

In response to Elow......

Yes, using a buffing compound on a wick is a technique that many techs use to polish the inside of outer slide tubes. If I am making a high-grade slide, I like to buff the inside of the outer tubes with yellow and then red rouge for a mirror finish before I assemble the slide. You must be careful not to bend the tubes in the process, so knowing the proper fitting of the wick is very important. If you get the tubes polished and absolutely straight, the slide can work perfectly with no lubricant.

I prefer wick polishing over the flex-hone polishing in most situations because the flex hone can result in small striations. I find the flex-hone is the best tool for bringing a slide with a little red rot back to life. Of course, usually the best remedy for red rot is to replace the slide tubes!

[BGuttman]

Sulfamic acid is a weakened form of sulfuric acid. One of the two hydrogens is replaced by an amine group.

Sulfamic acid is less corrosive to brass than sulfuric acid. Also less likely to create chemical burns on skin.

Weaker solutions take more time to work, but are much more tolerant of long immersion times. You don't need to pull at a particular second. Less stress.

[Doug Elliott]

Speaking of chemicals... I have some unused battery acid from way back when car batteries were sold dry, with a separate bag of acid. Is it good for anything?

[biggiesmalls]

FWIW, for polishing chrome plating on inner slide tubes, I use 3M polishing paper, 4000/6000/8000 grit. Very effective for smoothing burrs and nicks at the open end of the tube: https://www.riogrande.com/product/3m-tr ... ent/337308

[timothy42b]

Speaking of chemicals... I have some unused battery acid from way back when car batteries were sold dry, with a separate bag of acid. Is it good for anything?

I wouldn't know of a use. I bought hydrochloric once when I was doing some ceramic tile work (a job that I'll leave to the professionals from now on - it turned out good but was more work than I'd intended). But battery acid is sulfuric I think, and I don't remember any use.

I think drain cleaners are sulfuric.

[Crazy4Tbone86]

I never bought a car battery kit like that in the old days Doug, but I do remember stories about them. I remember a guy in my high school talking about a bag of powdered battery acid getting wet in their garage and leaking out of the bag. By the time they had discovered the problem, it had chewed a hole two inches deep in the cement garage floor!

Concerning those polishing papers....I like the idea of using them on the chrome plated inner slides! I never thought of that. I would still suggest that you move the polishing paper up and down the slide and not polish in a circular motion. Any striations that you create (even if microscopic) at a 90 degree angle to the action of the slide are going to create friction. I have seen some techs use 4000 grit and higher to polish piston valves. Although, I still think scratch brushing would be safer on pistons.

I was told by a guy who specialized in refurbishing antique furniture that thick paper (the type used for those yellow mailing envelopes) is approximately a 5000 grit. He used paper to polish the furniture between layers of polyurethane. When I do a touch-up lacquer job, the spray-can lacquer can feel a little porous when it dries. Sometimes I rub it gently with some paper to give the lacquer a smoother feel and even gloss. Now I'm thinking of the option of polishing inner slides with thick paper!

[JohnL]

Years ago, John Sandhagen recommended using bronze wool to clean up slide stockings. You can find it at some woodworking stores.

[timothy42b]

I was told by a guy who specialized in refurbishing antique furniture that thick paper (the type used for those yellow mailing envelopes) is approximately a 5000 grit. He used paper to polish the furniture between layers of polyurethane. When I do a touch-up lacquer job, the spray-can lacquer can feel a little porous when it dries. Sometimes I rub it gently with some paper to give the lacquer a smoother feel and even gloss. Now I'm thinking of the option of polishing inner slides with thick paper!

Paper is abrasive. I worked in a cardboard (corrugated) box factory out of college. The paper ran from big rolls at about 300 ft/sec as it was being glued together and it polished stainless steel plates shiny as it ran over them.

You could sharpen a pocket knife, theoretically, but you did not want to cause any burp in the line. The cardboard has to cook on the hot plates just long enough then be sliced into sections and stacked. Any time the line stops because you missed a splice or screwed something else up the section stays in the hot plates too long and has to be ripped out by hand and discarded - a couple hundred feet of hot steamy cardboard. Not a fun job.