How to repair "tarnished" gauges

[Dunc]

I lucked in at a recent garage sale and obtained a number of gauges: sheet metal (thickness), drill gauges (fractional inch, number, letter, metric), radius, etc. Most are in great condition; however, a few have a layer of tarnish that obscures the markings rendering them difficult (for my old eyes) to read. This is not rust - at least, not now. Perhaps it was rust that was treated by some type of rust removal process.
While wire brushing is one approach I am reluctant to do this in case it further obliterates the markings already present. I want to remove the tarnish, not the dimensional markings. Is another soaking in [whatever] something to try? What about fine wire brushing - Dremel - vs a 6" bench grinder? Alternately, can I enhance the markings? Suggestions appreciated. Thanks!

[Paul Alciatore]

My first thought would be a trip in the ultrasonic cleaner with something mild, like Dawn dish washing detergent. I would give it a good, long bath, perhaps a full hour. Then rinse and dry followed with a light coat of oil.

If that does not do it, try to post a photo so we can see the problem.

[boslab]

Fine abrasive rubber block
Mark

[RB140]

Try a bit of auto polish it takes of dirt and grime off of a cars paint why not off of tools and gauges

[Doozer]

Rub it with Brasso?
Or toothpaste ?
Try Comet or Barkeeper's Friend.

-D

[mklotz]

Happich Simichrome metal polish

http://Happich Simichrome metal polish https://www.amazon.com/Simichrome-390050-Metal-Polish-Tube/dp/B0002YUQ4E/ref=sr_1_1_mod_primary_new?crid=1XCEM9DROOZQK&keyw ords=happich+simichrome+polish&qid=1653488013&sbo= RZvfv%2F%2FHxDF%2BO5021pAnSA%3D%3D&sprefix=happich +si%2Caps%2C133&sr=8-1

[Doozer]

Happich Simichrome metal polish

It probably works well
but what a stupid name.
Almost as bad as Palmgren.

-D

[J Tiers]

Those gauges generally have engraved markings. So if you sand or polish the surface, everything will be clear again. Any tarnish in the engraving just makes the markings clearer against the clean surface.

[BCRider]

Those gauges generally have engraved markings. So if you sand or polish the surface, everything will be clear again. Any tarnish in the engraving just makes the markings clearer against the clean surface.

I was about to similarly suggest sanding with fine grit paper on a good stiff block and some light oil for doing just what JT posted. He beat me to it.

The issue with brushes or rags and polish is that it rounds over the edges of the stamped or engraved markings. You want a clean cut of the surface tarnish with sharper than before edges to the markings. Sanding with a flat hard block will give you that.

A lot of the tools will likely not be dead nutz flat either. So I'd go with a smallish block of aluminium and something like 320 to 400 grit silicon carbide paper so it cleans up the surface but can ride some minor arcs and hollows quite well.

Another option would be some fine valve grinding compound and a small block of hardwood.

[JRouche]

I lucked in at a recent garage sale and obtained a number of gauges: sheet metal (thickness), drill gauges (fractional inch, number, letter, metric), radius, etc. Most are in great condition; however, a few have a layer of tarnish that obscures the markings rendering them difficult (for my old eyes) to read. This is not rust - at least, not now. Perhaps it was rust that was treated by some type of rust removal process.
While wire brushing is one approach I am reluctant to do this in case it further obliterates the markings already present. I want to remove the tarnish, not the dimensional markings. Is another soaking in [whatever] something to try? What about fine wire brushing - Dremel - vs a 6" bench grinder? Alternately, can I enhance the markings? Suggestions appreciated. Thanks!

Before any mechanical means, including abrasives like brasso, simichrome and such I would try a solvent.

The reason I say that is because many of my tools like what you are talking about look like hell. Brown and tarnished looking. The reason is they have been drenched in a protectant that discolors after years. So when I need to use that tool I soak it in a vat of acetone I have and in 30 minutes its wiped clean. Just a thought. I like the US cleaner with dawn idea also. JR

[lynnl]

I've always gotten good results with "Never Dull" polish: https://www.google.com/search?client...l+metal+polish

It's a cotton wadding type material saturated with some sort of magic juice.
Can take a lot of rubbing. But doesn't do any damage, that I've ever noticed.

[JRouche]

I've always gotten good results with "Never Dull" polish:
It's a cotton wadding type material saturated with some sort of magic juice.
Can take a lot of rubbing. But doesn't do any damage, that I've ever noticed.

Yes!! It doesnt (I think) have any abrasives besides the cloth itself which is soft. I used to use it a lot. Dries the fingers out so it must be good JR

[J Tiers]

Before any mechanical means, including abrasives like brasso, simichrome and such I would try a solvent.

The reason I say that is because many of my tools like what you are talking about look like hell. Brown and tarnished looking. The reason is they have been drenched in a protectant that discolors after years. So when I need to use that tool I soak it in a vat of acetone I have and in 30 minutes its wiped clean. Just a thought. I like the US cleaner with dawn idea also. JR

There is a problem with that approach.

Yes, clean first, I assume the cleaning approach was tried, with detergent or the like. After a while, oil etc can become a hard coat that "cleaning" and sometimes even solvents, don't touch.

Using "strong solvents", purple cleaner, ultrasonic cleaning, etc has a problem. It works too well! And it does not "know" what you want to remove.

So, you remove the "tarnish", and also the paint in the engraved markings. Now your item is squeaky clean, but the markings are still hard to read because they are fully or partly removed to bare metal.

That is where "mechanical means" will shine...pun intended. They shine up the surface so you can see the engraving, but do not clean the contrast paint out of the markings.

[Doozer]

I know you are talking about steel plate gauges like feeler gauges and the like,
but for cleaning dial indicators with the plastic lens, I was always very careful
what solvent to use without hazing the plastic lens. What I have found that
cleans gook well and is safe to the plastic is Hoppes No. 9 gun cleaning solvent.

-D

[metalmagpie]

Judicious use of a glass bead blaster can work wonders.