Evaporust vs. wire wheel and buffing compound

[Tynyyn]

I enjoy restoring old handsaws.  The way I make the blade rust free is to run the blade underneath an 8" brass wire wheel attached to my grinder.  Then I use green buffing compound on a cotton wheel and after a half hour the blade seems bright and rust free.  I've done about ten blades and have been pleased with the success.  Though holding the blade under the wire wheel to knock the rust off is getting a bit tiresome.

So the other day I went to HF and picked up a gallon of Evaporust because I've seen youtube vids on its effectiveness and have seen testamonials on here and other forums.  I simply put the blades in a container of Evaporust and waited 24 hours and sure enough the rust just wiped off. 

My conundrum begins when I put the blades to the buffing wheel.  I used black, white, brown and green buffing compounds and was unimpressed with the results.  It seems that the evaporust left the blades with a gray coating and the buffing did not take the gray coating off. 

Has anybody else experienced this condition of the gray coating being left on their metal parts dipped in Evaporust?  What did you do to get that stuff off the metal?  How did you brighten up the metal after an Evaporust bath?

[Tynyyn]

From the manufacturer:

The black film is carbon from the steel. Steel is composed of a combination of carbon and iron. In certain instances, steel will darken in color after rust has been removed from the surface of the metal. This is a natural phenomenon that chemists refer to as “carbon migration”. The carbon from the steel moves, or “migrates”, to the outer layer of the metal and settles into the pores. The removal of the rust (iron oxide) reduces the proportion of iron to carbon, leaving a higher concentration of carbon on the outer surface. This heavier layer of carbon could cause a darkening of the metal due to the attributes of the carbon. The darkening does not have an adverse affect on the metal. It merely represents the movement of carbon from the interior of the metal to the exterior of the metal.

Since Evapo-Rust® is a highly effective rust remover, it stimulates the carbon migration process. Evapo-Rust®is not alone in creating the carbon migration effect. Other rust removal treatments will also result in carbon migration and a darkening of the metal. The primary difference between Evapo-Rust® and the acid based treatments is that Evapo-Rust® will not harm or weaken the metal. Unlike other treatments, Evapo-Rust® will not darken products made with low carbon steel.

With Evapo-Rust®, sometimes a wiping with a dry cloth or a more rigorous buffing can remove the dark coloring. A quick rinsing of the metal after Evapo-Rust® has been applied may also keep the carbon from settling into the pores of the metal.

There are several things that can be tried to minimize the effects of carbon migration. First, high carbon parts should not be soaked longer than necessary. Once the rust has been removed, the parts should be rinsed and dried. Second, a further dilution of the Evapo-Rust® formula may have a positive affect. The lower concentration of Evapo-Rust® will take longer to remove the rust, but may have less of an effect on causing the carbon migration.

I guess I answered my own question. I should have rinsed the blade and maybe not put it into the solution for 24 hours.

[Admiral]

I don't know of any saw doctors of repute that support any chemical rust removal treatment of handsaw plates.  Your quote from the manufacturer likely indicates why, as the treatment seems to migrate carbon from the steel, which from my understanding (I'm far from being a metallurgist) simply cannot be a good thing for a saw plate.  While they say it won't weaken the metal, the relatively thin plate of a saw seems to me to be a horse of a different color, as opposed to using the product on chisels, or planes, as you are migrating carbon from both sides of the plate, so my gut tells me that this just has to affect the teeth.  

Maybe someone with more knowledge of metallurgy can explain this in more detail, as my gut could be wrong; it wouldn't be the first time. 

Everyone I know who has been doctoring saws for some time universally suggest scraping with razor blades to remove the bulk of the rust, followed by lubed abrasives working up the grits, then steel wool/scotchbrite as appropriate to your last grit, then polishing compounds.  There is simply no easy way, and I've gotten the process down such that within an hour I get acceptable results.

[Jack in omaha]

Admiral has posted many examples of very nice tools so why try anything else. His results should speak well for his technique so I for one would like to thank him for sharing his results!



Which lubed abrasives work best?

[Mike Brady]

I concur with the other replies here so far and will add that I don't recommend any wire brushing (powered) being used on tools.  Small wire detail brushes are ok.. I use welder's brushes that are basically a brass or stainless toothbrush.  Evapoprust is a great help, but absolutely not on saw plates.  Instead of wire wheels I like deburring wheels.  They do not alter the surface of bare metal; just brighten it.  Don't use them on plated parts such as nickel-plated lever caps because they will remove plating. Deburring tools are great for irons, chisel blades...anything relatively hard.

The good restorers (and some of them have answered here) use a kind of less-is-more approach to cleaning; instead of trying to re-manufacture the tool and make it look new.  To pick one, because he posts here often, look at Admiral's S&S listings.  Those tools look well-cared-for, not restored.  Making a tool look new, unless it is new, can lower its value.  If you use tools once they are cleaned up, they develop the "patina" fairly quickly anyway.  They were made to be used.

[Admiral]

Which lubed abrasives work best?

I lube my abrasives with windex, actually a noname HD window cleaner. And use sandpaper, working up the grits, followed by scotchbrite and then Autosol polish. This cleans the plate. Then the reforming of the teeth follows, then set and sharpening. You can have 3 hours or more invested in rehabbing a saw. Not for the faint of heart, but very satisfying.

[JimReed@Tallahassee]

I have removed lots of rust from lots of tools. In my experience saws respond differently from other tools and the only effective rust removal I like is 400-800 AO sandpaper and Simple Green. Saw plates get pitted from rust. Chemicals seem to lighten the colors of those pits and thus ruin the natural patina. Saws cleaned with light sanding seem to develop (retain?) a pleasing patina. After treatment, I wash with soap and water to remove any residual salts and the Simple Green. Drying quickly and rubbing down with 3 in 1 oil finishes the process.

As Admiral says, working over a saw properly takes hours. Add a few more hours for handle repair and refurb can total up to a working day. Those of us who do it find the work both challenging and rewarding--spiritual, not financial.

[AHill]

I've had success with abrasive cleaning after Evaporust to get rid of the gray.  The chemical process Evaporust uses is called chelation.  While it mostly just attacks the rust, it does leave behind that gray.  That gray is carbon migration and it comes from the carbon that was in the in the rust, not the carbon that was in the steel.

[Admiral]

That gray is carbon migration and it comes from the carbon that was in the in the rust, not the carbon that was in the steel.

Allan:  I'm not so sure its from the rust, as the blurb from Evaporust says ". . . the darkening does not have an adverse affect on the metal. It merely represents the movement of carbon from the interior of the metal to the exterior of the metal."  This is what concerns me, especially with the high carbon steel in saw plates.  It may be so little that it is immaterial, I'm not smart on metal so again, its my gut talking here.

Where's a metallurgist when you need one!  

[AHill]

Allan:  I'm not so sure its from the rust, as the blurb from Evaporust says ". . . the darkening does not have an adverse affect on the metal. It merely represents the movement of carbon from the interior of the metal to the exterior of the metal."  This is what concerns me, especially with the high carbon steel in saw plates.  It may be so little that it is immaterial, I'm not smart on metal so again, its my gut talking here.

Where's a metallurgist when you need one!  

I am a metallurgical engineer (B.Sc., Met.E., Colorado Mines 1978).  At best, the carbon depletion of the base metal is a couple of ten thousandths of an inch deep.  Chelation, by its nature, attacks iron oxide, not the steel.

I'm not sure where you found the statement about the carbon depletion.  I can't find it anywhere on their website.  It conflicts with the mechanism of the chelation chemical process. It also conflicts with their claim that it does not harm unrusted steel.  Here's what they say about the process:

"The Selective-Chelator is not strong enough to remove Iron-to-Iron bonds from un-corroded steel and does not harm the underlying metal."

I have emailed Evapo-Rust to ask them to clarify.  I've also asked them to characterize the depth of carbon depletion, if that is the case.