Aluminum smears on granite, how to remove?

partsproduction · Oct 7, 2021

Hi,
I was doing layout work on the surface plate on a 3 1/2 X 6 1/4 X 11 1/4" 7075 block, not thinking about the aluminum streaks on the granite plate until too late.
I know drain cleaners (sodium hydroxide) mixed with in a strong solution will make the bright smears to disappear but I'm concerned about the granite of the plate. This is a black granite plate if it makes a difference.
Thanks, for any help.
parts

Demon69 · Oct 7, 2021

partsproduction said:
Hi,
I was doing layout work on the surface plate on a 3 1/2 X 6 1/4 X 11 1/4" 7075 block, not thinking about the aluminum streaks on the granite plate until too late.
I know drain cleaners (sodium hydroxide) mixed with in a strong solution will make the bright smears to disappear but I'm concerned about the granite of the plate. This is a black granite plate if it makes a difference.
Thanks, for any help.
parts

At the risk of being controversial, a sizable flat soft white aluminium oxide stone lubed with mineral spirits, floats over the surface and wipes of metal smears and doesn't touch the granite. You can really feel it catch anything that's standing proud.

boslab · Oct 7, 2021

Avoid chemicals, standrige granite site or contact them, it’s easy to make a headstone out of a granite plate
Mark

jhov · Oct 7, 2021

Demon73 said:
At the risk of being controversial, a sizable flat soft white aluminium oxide stone lubed with mineral spirits, floats over the surface and wipes of metal smears and doesn't touch the granite. You can really feel it catch anything that's standing proud.

Is this controversial? Precision ground flat stones are perfect for removing raised material from flat surfaces.

Scottl · Oct 7, 2021

Try a small spot of the caustic on the back or side of the plate where it won't affect the precision surface.

Larry Dickman · Oct 7, 2021

Angle grinder with a diamond blade will work.

Or, I have found the streaks just disappear on their own.
I like to work on a 2 4 6 block to avoid wear/smudging the plate.

Illinoyance · Oct 7, 2021

I used lye dissolved in water.

Mtndew · Oct 7, 2021

Denatured alcohol won't do the trick?

Demon69 · Oct 7, 2021

jhov said:
Is this controversial? Precision ground flat stones are perfect for removing raised material from flat surfaces.

Controversial in the sense of using abrasives around a granite flat.
Ime, aluminium oxide doesn't touch granite at all, silicon carbide will cut for a short while before dulling off, diamond cut's granite like butter.
The stone doesn't have to be 'Robin' flat, I kept mine clean and flat to a fashion on cast iron lap impregnated with diamond.
The main bit is the AO stone will cut deposits of material without cutting granite.

partsproduction · Oct 7, 2021

I used lye dissolved in water.

Of course I mentioned that as drain cleaner.

The plate was made by A. Ottavino in the early 90's. Maybe I can call them and ask.

partsproduction · Oct 7, 2021

Thanks for all responses.
I did send a question to A.Ottavino corporation about lye to clean surface plates (And why) but I have to say, the website showed only granite for buildings and monuments with a the exception of one small area that showed a surface plate magazine ad looking to be from around WW2.
So I wonder if they still make plates.

PS the aluminum smears don't stand above the surface, if at all it would seem micron size heights. It just makes white colored streaks so it's probably as thick as a pencil mark.

EmGo · Oct 7, 2021

partsproduction said:
It just makes white colored streaks so it's probably as thick as a pencil mark.

Did you try an eraser ?

edwin dirnbeck · Oct 9, 2021

partsproduction said:
Hi,
I was doing layout work on the surface plate on a 3 1/2 X 6 1/4 X 11 1/4" 7075 block, not thinking about the aluminum streaks on the granite plate until too late.
I know drain cleaners (sodium hydroxide) mixed with in a strong solution will make the bright smears to disappear but I'm concerned about the granite of the plate. This is a black granite plate if it makes a difference.
Thanks, for any help.
parts

Unless you borrowed some ones plate plate and are embarrassed,FORGETABOUTIT. Unless you are working in a temp. controlled shop really really holding .0001 tolerances EVERY DAY ,your surface plate ,will be good for your lifetime Edwin Dirnbeck

edwin dirnbeck · Oct 9, 2021

partsproduction said:
Hi,
I was doing layout work on the surface plate on a 3 1/2 X 6 1/4 X 11 1/4" 7075 block, not thinking about the aluminum streaks on the granite plate until too late.
I know drain cleaners (sodium hydroxide) mixed with in a strong solution will make the bright smears to disappear but I'm concerned about the granite of the plate. This is a black granite plate if it makes a difference.
Thanks, for any help.
parts

Unless you borrowed some ones plate plate and are embarrassed,FORGETABOUTIT. Unless you are working in a temp. controlled shop really really holding .0001 tolerances EVERY DAY ,your surface plate ,will be good for your lifetime Edwin Dirnbeck

Joe Rogers · Oct 10, 2021

I would continue to look for a removal solution. Given aluminums propensity to oxidize and create aluminum oxide, I sure wouldn't want random abrasive stuck to my plate.
Joe

bhigdog · Oct 10, 2021

Spray on oven cleaner. Let sit for 10 minutes before wiping off........Bob

Bill D · Oct 10, 2021

Use lye and some water, not drain cleaner. A slower, safer reaction. Still wear goggles and gloves.
Drain cleaner is lye with Aluminum chips. The Al is to impress the user. All it does is react with the lye, thus neutralizing it, this causes the mix to get hotter. dangerously hot, possibly a steaming blow up into your face. This reaction uses up the lye before it can react much with the grease and hair causing the problem. Then you have to buy more. It will not continue to work overnight since the lye has all reacted with the AL.
Pure lye and water will slowly react with the problem stuff until it is all reacted or the bad stuff is all gone.
Bill D

Mark P. · Oct 10, 2021

Try GOJO hand cleaner with pumice in it. Cleans very well

Eric M · Oct 11, 2021

Scotchbrite pads (or the like) worked for me in the past. Followed up with Starrett surface plate cleaner. Never had an issue when the plates were calibrated.

Toolmaker51 · Dec 29, 2022

Mark P. said:
Try GOJO hand cleaner with pumice in it. Cleans very well

A lot of answers, but only this is a reasonable first step. The pumice and orange peel oil won't bother a thing but dirt. Normally, plain lanolin hand cleaner is fine; a white paper towel discloses what contaminates may have been there.
Afterward, a cleaning with 90% denatured alcohol with about 1/4 volume plain water. Drys fast and uniform.
Freebie: surface plates deserve a cover. Toolhouses sell naugahyde fitted blankets that extend over the edge, one $olution Big wow, piped edges.
Someone knows who has a sewing machine too, same thing at 1/4 cost.
A1 choice on a bigger plate is a little wood molding, plywood/ masonite and piano hinge or two. Protects unused area, makes larger instruments unlikely to park there, and if desired can swap open ends between re-calibrations.

Aluminum smears on granite, how to remove?

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