Thread: Crocus finish or Satin?

Originally Posted by hatzicho

Very interesting read, thanks for the addition.
Some questions. What kind of emery do you use on your wheels and what is the green rouge - never heard that? Sounds like a green and red paste in one ...
In the razor cutlery we use either green paste, means chromium oxide for mirror polish, or red powder. The red powder or paste is based on iron oxide and gives a much better mirror polish. It isn't used quite offen these days because the red powder lays down everywhere in the workshop while polishing. In the older days polishing with red iron oxide was called "fox polishing" because of the red color. The tools and the polishers themselfes were covered in red and looked like a (red) fox. That's why the red polishing went out of fashion already in the 1930th/1940ths, when the green paste enters the market.
But with some experience you can clearly see on old razors if they are green or red polished. Also red polished surfaces are more stable. They don't get scratched so easily like green polished surfaces.
I also like to use tripel as a (pre-) polishing powder/paste.

Regards Peter

The emery we used was just a standard grease compound emery, the green rouge is a fine polishing compound designed for the final polishing of stainless steel/chromium plate. Dico is the manufacturer. It's amazing how fast the emery can cut, we would actually use it in conjunction with a felt wheel as a sort of soft grinding medium for some of our instruments. One I used to grind and polish was called an IPC (Interproximal Carver) It looks kind of like a small hockey stick, 10mm long blade, 60 thou wide, tapering from 10 thou at the heel to 5 thou at the tip. We used the emery with a rocking motion to cut down the thickness from the blank and to create a double clamshell cross-section which resulted in a sharp cutting edge around the perimeter. Back to compound, a lot of green compounds used to use chromium oxide but now many contain a mix of chromium oxide and aluminum oxide or just mostly aluminum oxide. I use the Thiers Issard cromox on my strop and it obviously removes metal. Before that I was using the Herold Strop Pastes, the small red and black cakes but they didn't really seem to do much at all. Red rouge, unless I'm mistaken is a bit too soft for use on steel, or at least you would be polishing for a very long time. The crocus compound used on the old Sheffield razors would have contained both red and black iron oxides, giving it a purple color. Black iron oxide, Fe3O4, can be bought in powder form although I'm not sure how fine the particle size is. It is otherwise known as Magnetite. It has a higher Mohs hardness than red rouge and is more suitable for polishing steel afaik but it sounds like you've used the red compound on steel. What are the polishing times like on a razor using red rouge?

Well colors of the ready to use pastes you can buy are vacant these days. The incredients differ from producer to producer, there are green pastes that are much coarser than the normal chromium oxide and so on.
I never use ready to use pastes, I produce all pastes that I use by myself, based on old receptures from grinders and my own experience. You can buy nearly all grinding and polishing powders as pigment.
So chromium oxide green is nearly all the same concerning the average or maximum particle size, that is around 0.3 µm. Concerning the red iron oxid Fe2O3 you can get variable particle sizes between 0.07 µm - which is much finer than chromium oxide - and > 1 µm.
You are correct that the ancient Sheffield polish was a mixture of several iron oxides that was mined as a natural product. It was developped around 1700 by the swedish engineer Christopher Polhem. The Solingen grinder Daniel Peres did a lot of efforts and years of experiments to recreate this polish by mixture of different iron oxides beginning of the 19th century.

Indeed the particles of red iron oxide are not as stable as chromium oxide particles. But that is also part of the trick, the particles getting smaller during polishing and therefore create a more mirror polishing. The problem is, that the surfaces must be very well prepared and nearly already without deeper scratches to use iron oxide. Otherwise you simply polish the scratches - which makes them even more visible on the surface.

As for the time you need for ploshing that is hard to say. If the surface is well prepared you can do the job quite quickly. But it is necessary that the metall surface heats up, therefore a certain pressure is needed. But I found that polishing with iron oxide you don't need so much pressure and time as when you polish with chromium oxide.

Regards Peter

Originally Posted by hatzicho

Well colors of the ready to use pastes you can buy are vacant these days. The incredients differ from producer to producer, there are green pastes that are much coarser than the normal chromium oxide and so on.
I never use ready to use pastes, I produce all pastes that I use by myself, based on old receptures from grinders and my own experience. You can buy nearly all grinding and polishing powders as pigment.
So chromium oxide green is nearly all the same concerning the average or maximum particle size, that is around 0.3 µm. Concerning the red iron oxid Fe2O3 you can get variable particle sizes between 0.07 µm - which is much finer than chromium oxide - and > 1 µm.
You are correct that the ancient Sheffield polish was a mixture of several iron oxides that was mined as a natural product. It was developped around 1700 by the swedish engineer Christopher Polhem. The Solingen grinder Daniel Peres did a lot of efforts and years of experiments to recreate this polish by mixture of different iron oxides beginning of the 19th century.

Indeed the particles of red iron oxide are not as stable as chromium oxide particles. But that is also part of the trick, the particles getting smaller during polishing and therefore create a more mirror polishing. The problem is, that the surfaces must be very well prepared and nearly already without deeper scratches to use iron oxide. Otherwise you simply polish the scratches - which makes them even more visible on the surface.

As for the time you need for ploshing that is hard to say. If the surface is well prepared you can do the job quite quickly. But it is necessary that the metall surface heats up, therefore a certain pressure is needed. But I found that polishing with iron oxide you don't need so much pressure and time as when you polish with chromium oxide.

Regards Peter

Interesting point there at the end about the metal heating up in polishing. Something I've noticed is that when using a coarser polish like an emery you really want the metal to be cool, I've noticed that if you get a lot of heat build up that you get a kind of tearing out of the metal, under a loupe you get these tiny pock marks with a comet tail effect which is very noticeable as you move to finer and finer polishes. But when you get to the fine polishes you want some heat in the work to almost create a burnishing effect. Maybe it's the same smearing but just on such a fine level it seals the metal somehow. I wonder if this is the reason that, at least in my experience, you never see a full mirror finish on full hollow/thin grind razors, that the pressure and heat needed for a nice polish might ruin the temper or flex the blade too much? I think some makers do polish but it is very light and you can still see the very fine lines from the grinding/glazing operations.


Can you share anything about the compounds that you make? I've always wondered how they used to do stuff in the old days. Kind of incredible some of the things you see from then. I have an amateur interest in pocket watches and when you look back to some of the quite old verge-fusee escapement pieces, the level of polish on the steel parts is amazing considering what they had to work with. But then again it seems our forebears were more advanced than we are aware, so much has been lost to history.

It is fascinating to eavesdrop on the conversation between two polishing pros. Thank you.

Dear Peter, @hatzitcho what is that schimergel paste, they put on the blades ( not on the wheel) while they are doing blaupliesten. I saw it in the video of Mr. Breidenbach and in the video of late Mr.master Wilfried Fehrekampf

https://www.youtube.com/watch?v=heIq9I1wjmA

.

Hi Taskin,

it is called Naxos emery and it is the same material the wheels are glued with. For the application during pliesten/ polishing the powdered emery is stired into rapeseed oil and smeared on the razor or on a metall blade and applicated on the wheel.
The emery was produced from abrasive rocks mined on the creek isle of Naxos. The stones had been broken and shipped to Germany and elsewhere. Here special milling companies prepared the powder in different qualities. Coarser qualities had been graded by sieving, finer qualities had been muddled.
For knifes and razors mostly the muddled products have been used. They were graded in 6 degrees, called 1/0, 2/0, ... 6/0. These grades are not directly transferrable to the grits we know today, since the emery doesn't have one defined grit, but a grain size distribution. So it is the same as if you compare natural stones to artificial hones. But concerning the main/max. particles sizes, a 1/0 corresponds to a 180 grit, a 5/0 to approx. 400 grit. For blue polishing Naxos 3/0 or 5/0 is used.
The Solingen production companies did mix some other incredients to the sole emery, such as red iron oxide (this is why the emery is of red color instead of grey - which is the normal color of emery), pumice flour and other polishing substances. The recepture was a strong secret of each company.
One of the best know companies was Carl Wester, Solingen.
Here is a picture of the original emery bags with label and some wheels that I glued with emery just a few days ago.



Regards Peter

Hi Peter
Thank you indeed. Fog in the brain disappeared.
Taskin