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Over the years I've met several old time tractor, antique aircraft, and antique car guys that swear by using Bon Ami Cleanser to deglaze pistons and to get rings to sit properly and fix blowby. Basically just dump a whole bunch of it into the carburetor while the engine is running.. let it run for a few minutes.. then change the oil.

I was thinking that it could make a attractive lapping/polishing compound for slides compared to, or maybe when used with, Lava Soap. Bon Ami is a mix of Limestone (95%) and Feldspar (5%) that is milled very fine around 20 microns (0.0008"..8 tenths). The limestone is about the same hardness as Cu-Ni 3ish on the Mohs scale.. while the Feldspar is about 6. The pumice in Lava is coarser and similar hardness to the Feldspar. Feldspar is highly friable is cleaves cleanly along several different planes meaning its cutting action is self regulating as it breaks down pretty quickly. Pumice on the other hand has an amorphous structure and shatters like glass rather than cleaving like a diamond.. it stays sharp and aggressive longer.

My thinking is that it is gentler.. but you can easily make up a slurry that has a lot more particles compared to Lava soap suds in oil.. also it can quickly be wiped and reapplied quickly.. just some thoughts

Anyone ever try it?

Personal opinion: I think that Bon Ami, and its analogues Comet and Bar Keepers Friend, among others, are too harsh. If a Scotch Brite pad doesn't help things by simply removing crudded lubricant, flaky corrosion, or other discoloration on the slides, the most abrasive I have done personally is to purchase a bar of Lava soap, rub up a lather, and apply that while working the slide or taking the valve up-and-down in the valve casing, and only then a little bit. Then completely rinse and dry everything clean so no residue remains. Did I say rinse and dry, rinse and dry, rinse and dry?

If whatever you are working on needs any more than that, then let us all sing the mantra to the tune of the William Tell Overture:
To the Tech
To the Tech
To the Tech, Tech, Tech

I use Lava soap for lapping in slides, but others have brought up elsewhere that the pumice can become embedded in the metal.

Ferree's sells stuff made with garnet. I am sure you can get garnet powder elsewhere for cheaper than what Ferree's sells ($57 for a tub!). Someone whose opinion I trust recommends the garnet-based compounds.

I might buy some of this Bon Ami stuff and see how it works... plenty of junky trumpets around here to sacrifice to the cause.

iiipopes wrote: Thu Oct 15, 2026 12:19 pm The most abrasive I have done personally is to purchase a bar of Lava soap, rub up a lather, and apply that while working the slide or taking the valve up-and-down in the valve casing, and only then a little bit. Then completely rinse and dry everything clean so no residue remains. Did I say rinse and dry, rinse and dry, rinse and dry?

This should be moderately less aggressive than Lava..

I was asking because I have an Olds Special trumpet that I am reversing the 1st and 3rd slides as a favor for a friend. 1st if fine because I am using the same tubing. 3rd requires a bit of lathework on the inner and the outer is coming from the main tuning slide of a similarly aged Olds Ambassador. The tolerances are a tiny bit off and the slide is a bit tight even when perfectly aligned (~0.001 clearance between outer ID and inner OD if my skill with small bore gages can be trusted.. I the past I've used Bloke's Lava method.. I want to try this, thinking it might work.. and be easier to clean than lava since it shouldn't embed like pumice can... but also want to see if anyone had any experience.

I will probably give it a try on a junk trumpet and see how it goes and report back.

gocsick wrote: Thu Oct 15, 2026 1:32 pmI will probably give it a try on a junk trumpet and see how it goes and report back.

Hmm. "junk trumpet" hmmm. Make sure the slides are already aligned well, or it won't do any good.

iiipopes wrote: Thu Oct 15, 2026 3:11 pm

gocsick wrote: Thu Oct 15, 2026 1:32 pmI will probably give it a try on a junk trumpet and see how it goes and report back.

Hmm. "junk trumpet" hmmm. Make sure the slides are already aligned well, or it won't do any good.

@gocsick has done some really cool stuff -- cut his own C trumpet(s? multiple?) and Eb trumpet, and has expert machining/mechanical chops, but he is modest. I bet he can handle it!

The only other time I've ever heard of Bon Ami was on The Price is Right!

Lava soap is probably equivalent of about 400 grit and Bon Ami is probably about 1000 - if you're comparing them to sandpaper.

Bon Ami would probably take too much time.

something else: Nickel brass within nickel brass takes an awfully long time as well.

I'm sure the first thing you're doing is getting all the tubes absolutely parallel, parallel within parallel, and coplanar.

The next thing to check for before it any sort of lapping operation is bulges in the ends of the inside slide tubes.

Even with expensive calipers, it's easy to get the incorrect measurement for the spacing of the inside slide tubes by measuring the "correct" place on the outside slide tubes.
A safe way is to pull a slide most of the way out where is very little tension on the inside slide (and maybe even do a little gentle bending, and conform the far end of the inside slide to the far end of the outside slide - so there's a little tension as possible, and - at that point - measure the inside slide spacing.
Once you've succeeded in getting the entire inside slide at that spacing standing alone, you might be ready to start lapping.

To assume that any tuba slides are parallel and coplanar and parallel within parallel from any factory is pretty laughable.