Abrasives
	Finest abrasives.
	Microbevels front and back.
	Use a jig.
	Copyright (c) 2002-09, Brent Beach

Contents

• Questions about abrasives and steels
  • General discussion of abrasives.
  • How can you build up a slurry using these abrasives?
  • Steel determines initial sharpness, right?
  • What is the best steel alloy for woodworking tools?
• Web site navigation

General discussion of abrasives.

1. What are abrasives?
2. Photomicrographs
3. How can 3 grits work, when everyone knows you need 8 or 9 grits?
4. Where can I get 3M Micro-abrasives?
5. What are these microns?
6. How does the micron measure compare to other grit measures?
7. What about abrasive hardness?
8. And grit sharpness
9. Other abrasive selection factors
10. Proprietary abrasives

1. What are abrasives?

   Abrasives are either naturally occurring or synthetic minerals. The molecules of the mineral align into lattices (regular 3 dimensional arrays) with very strong bonds, producing crystals with hard and sharp corners. The most commonly occurring natural abrasives are oxides of aluminum and silicon. The most common synthetic abrasives are aluminum oxide, silicon carbide, and newer minerals like boron nitride.

   Mineral	Found in	Hardness (Vickers)
   Diamond	Diamond hones
   Silicon Carbide (SiC) carborundum	SiC abrasive papers Norton Crystolon stones	4880
   Chromium oxide (CrO)	CrO abrasive papers Green stropping compound abrasive powder used on oiled strops	2995
   Aluminum Oxide (AlO) corundum	AlO abrasive papers Norton India Stones Japanese water stones white stropping compound	2085
   Silicon Oxide (Novaculite)	Some naturally occurring oil stones natural Arkansas stones Tripoli rouge
   Ferric Oxide	Red rouge

2. Photomicrographs

   Images of many different abrasives at 450 times magnification.

3. How can 3 grits work, when everyone knows you need 8 or 9 grits?

   Early versions of sharpening using abrasives on glass use a single honing angle. With each abrasive the smoothed the entire honing bevel. With the jig and slips, you increase the angle with each abrasive so that you start honing at the edge. You quickly hone through the old scratches.

   In spite of the simplicity of the jig, it is extremely precise. The use of the slips ensures that the second and third microbevels are precisely positioned. If you hone on the 5 micron paper until the bevel is 0.01" wide, you have actually removed 0.00035" of metal, right at the edge. This accounts for all the scratches made by the 15 micron paper. If your 0.5 micron microbevel is half that wide, 0.005", then you have removed 0.00018" of metal, right at the edge. Again, all scratches left by the 5 micron paper are gone. There really is no advantage to using more grits.
   
   

4. Where can I get 3M Micro-abrasives?

   This is what I know about 3M microfinishing abrasives.
   
   

5. What are these microns?

   The microns used to define the grit size on the 3M Micro-abrasives are millionths of a metre. I should stick to one system or the other, but often mix in inches when describing the width of a microbevel or the size of a jig. Unfortunately, all my measuring tools are older so measure in inches.

   So, 1 micron is 0.00003937". The wavelength of visible light is between 0.000016" (purple) and 0.00007 cm or 0.000028" (red).
   
   

6. How does the micron measure compare to other grit measures?

   Abrasive grading systems general specify a method of measurement, a range for the average grit size, a range into which almost all the grits must fall, and a maximum grit size. Comparisons of ratings in the various systems usually only compare the average grit size. If the range of grit sizes allowed in one system is large (waterstone ratings) and in another very small (micron ratings) then comparison of average between the systems is meaningless. The European P grading system is more finely controlled than the US or Japanese, and the micron grading system is more finely controlled than the P system.

   A micron grading system makes no sense for natural stones - no natural stone would meet the spec because there is too much grit variation. The US system was originally designed to grade natural stones. Now that almost all abrasives are synthetic, using abrasives sized against the tightest grading system - the micron system - gives the best results.

   This table shows the various standards in the grit sizes. I obtained this information from the internet over the years and am unsure of the sources. The standards are:

   1. The USA column has the ANSI/CAMI (Coated Abrasives Manufacturers Institute) standard grit designation.
   2. The Japan column has the JIS (Japanese Industrial Standards) designation for Japanese water stones. UPDATE - it would appear that since I first collected this material the JIS standard has changed. The JIS NEW standard has smaller micron sizes for the same grit designation. So, while 2000 grit was about 8.5 microns in the old standard, it is about 6.7 microns in the new standard. The standard allows a few particles that are as much as 5 times as large as the average - for 8000 grit, while the average is 1.2 microns, the largest allowed is 6 microns. It may well be this inclusion of much larger grits in nominally smaller abrasives which produces the speed of cutting.
   3. The Europe column has the designations for the FEPA (Federation of European Producer of Abrasives) grit sizes. These P grades allow less variation from the average - fewer larger grits and fewer smaller grits - than the ANSI/CAMI system allows. This standard specifies
      • a midpoint range - the average must fall in this range, usually one or two microns across the range;
      • a lower cutoff - 94% of the grits must be larger than this;
      • an upper cutoff - 97% of the grits must be smaller than this.

   The comparison is only approximate. Thus, the average particle size for P1200 is 15.3, for CAMI 600 is 14.5.

   Note that these are average sizes. The quality of the abrasive paper is also determined by the variation in size, the level of impurities within the abrasive, the quality of the bond and of the backing. If you cannot find 3M Micro abrasives where you live and mail order is prohibitive, then look for very high quality abrasives.
   
   

   Source	USA	Japan	Europe	Average grit size in microns
   	60			250
   	80			180
   Coarse Crystolon	100			150
   	120			106
   Medium Crystolon	150			90
   	180			75
   Fine Crystolon	240			58.5
   40 micron SiC paper	320		P360	40
   Washita oil stone	360	600	P500	30.2
   	400		P600	25.75
   Soft Arkansas stone				20
   	500		P1000	18.3
   15 Micron belt, 15 micron SiC paper	600		P1200	15
   Hard white Arkansas, extra fine diamond, and medium ceramic	700	2000		14
   Hard black Arkansas, 9 micron belt	1000	4000	P2300	9
   			P2400	8
   5 micron SiC paper	1200+		P4000	5
   Extra fine white Ceramic, green chrome rouge, 3 Micron belt.	1500	6000		3
   Japanese Water stone		8000		?
   Japanese Water stone		15000		0.9
   Chromium oxide polishing compound, 0.5 micron Chromium oxide paper				0.5

   NOTE 1: The green crayon sold by Lee Valley is advertised as "primarily chromium oxide admixed with other fine abrasives (0.5 micron particle size)". It should read "primarily chromium oxide (0.5 micron particle size) admixed with other fine abrasives." The other abrasives have much larger average size. See my web page explaining why you don't want to strop plane irons.

   NOTE 2: Some manufacturers' Grit designations fall outside these guidelines. I have seen reports that Shapton 8,000 grit waterstones have average particle size 1.84 microns, while the Norton 8,000 grit waterstones have average particle size 3 microns.

   Note 3: The Shapton grit designation appears to be particularly irregular. Their very fine stones, designated 30,000 grit, clearly contain very large grits. A 3M abrasive marked 5 micron will have far less grit size variation. The Shapton grit size times the micron grading is about 14,700. However, since the Shapton stones are not micron graded, the distribution of grit sizes within a stone can be different from micron graded abrasives.

   Note 4: These grit grading systems apply to coated abrasives - those used in abrasive papers. There is a different grading system that applied to bonded abrasives - those used in grinding wheels.

7. What about abrasive hardness?

   Aside from grit size, the most important factor in an abrasive is its hardness.

   One of the standard measures of hardness is the MOHS scale, which rates minerals on a scale from 1 to 10. This table shows some common minerals.
   
   

   MOHS
   Hardness	Material	Source
   10	diamond	Diamond stone, diamond paste
   9.5	silicon carbide	carborundum, 3M 15, 5 micron abrasive paper
   9	aluminum oxide	corundum, Ruby, Sapphire, AlO abrasive paper, India Stone
   8	aluminum silicate	Topaz
   7.5	beryllium-aluminum silicate	Emerald
   7	silicon dioxide	Quartz, Arkansas sharpening stones
   7+	hardened steel	files, plane blades, tool steel
   6	cerium oxide	lapidary abrasive, not for metals

   
   The MOHS scale is not linear or logarithmic. Rather, the originator of the scale selected 10 common minerals, ranked them for hardness, and assigned numbers to each. The change in hardness from one level to the next is tells you almost nothing. For example, the minerals from quartz at 7 to sapphire at 9 will scratch each other.

   Diamond is much harder than everything else. Even though Diamond has value 10 and Silicon Carbide has value 9.5, Diamond is "5 times harder" than Silicon Carbide.

   Most water stones (natural/synthetic) are aluminum oxide based. Natural oil stones (Arkansas) are silicon dioxide (silica, SiO2) and are also known by the name of the mineral -- Novaculite.

   Some of the harder/tougher steels appear to require harder abrasives (at least silicon carbide, possibly diamond).

   The Wikipedia entry on the MOHS scale is informative. It contains another measure, called absolute hardness. On this scale, talc is at 1, corundum at 400, and diamond at 1500. This small table does not list Silicon carbide or Chromium oxide. The Wikipedia contains entries on all the minerals in the above table, plus lots more.

   An extended MOHS scale, extended to include minerals not known in Mohs' time:

   Extended MOHS
   Mineral	Extended scale hardness
   Fused Zirconia	11
   Fused Alumina (Al2O3)	12
   Silicon Carbide (SiC, carborundum)	13
   Boron Nitride (BN) (hexagonal)	14
   Diamond	15

   
   Again, unfortunately, these numbers rank the minerals without indicating relative hardness.

   Attempting to find a better hardness scale, I have found some results from various areas using the Vickers scale. Most of these numbers came from a site called MatLab, but some came from other sites. The Vickers hardness of various abrasives and steel carbides:

   Vickers
   silicon carbide	4483
   chromium oxide cr2o3	2955
   alumina Al2O3	2085
   vanadium carbide	2950
   titanium carbide	3200
   tungsten carbide	2400

   These numbers compare the hardness of the various types of carbide particles in steels (see below for the composition of tool steels) to the hardness of the abrasives. Silicon Carbide is harder than all the carbides you might find in steel. Chromium Oxide is also pretty hard. Alumina unfortunately is not as hard as typical carbides.
   
   

8. And grit sharpness

   Another factor in abrasive grinding power is the shape of the grit. All grinding compounds we use are minerals - they all have a crystalline structure. Some shapes are sharper than others though. This link connects you to an article which discusses the shape of the abrasives. Some points it makes:
   
   

   AlO	"a single-crystal grain used in most polishing applications because of its durability and longer service life than silicon carbide's" "Soft metals such as aluminum and some carbon and stainless steels usually are good candidates for aluminum oxide."
   SiC	"a single-crystal grain, is the sharpest and hardest of all grains, but it is also the most brittle of all, resulting sometimes in a short service life" "Silicon carbide's sharp shape and extremely hard properties make it the most suitable grain to work on titanium, cobalt, and INCONEL® alloys."

   
   
   

   I tested "open-coat" 60 grit AlO for grinding the primary bevel. I got many edge fractures (pictures on that page). I never get edge fractures when grinding the primary with a coarse SiC benchstone. It may well be that "open-coat" abrasives should not be used on edge tools. Or, it may be that SiC brittleness is a benefit, not a drawback. Perhaps the SiC abrasive shatters before the edge!

9. Other abrasive selection factors

   In addition to grit size, hardness, and shape, the performance of an abrasive depends on: the uniformity of the particles, the strength of the bond and the strength of the backing material.

   The 3M microfinishing abrasives show uniform scratching patterns in the pictures I have taken. On the other hand, the honing compounds I have tested show a wide range of scratch sizes.

   Plane blade sharpening is a low pressure, low heat application -- you would not expect a reasonably good paper to have pieces of grit pop off the paper. This can happen with cheap papers though. If you are using an abrasive paper which sheds grits it is time to look for another brand.

   The backing material need not be able to handle really large forces. The only real problem is that the wire edge can rip the paper. If you push the blade rather than pull it when you first go to the next lower grit, or when you flip from one side to the other, you could rip the paper. The 5 micron 3M paper without the PSA backing is actually susceptible to ripping.
   
   

10. Proprietary abrasives

    There are a number of sharpening stones and grinding wheels available which are composed of a number of different abrasives. For example, the Material Safety Data Sheet for Norton Crystolon Sharpening Stones reports:

    
      SUBSTANCE DESCRIPTION                PERCENT     CAS#
      --------------------------------------------------------------------------------
     Amorphous Silica, Fused          10.000- 20.000  60676-86-0
     Silicon Carbide                  80.000- 90.000  409-21-2 
    
    

    As well, "The variation in Silicon Carbide to Amorphous Silica is due to the different combinations with the different grits." You can see the Materials Data Sheet for their Aluminum Oxide and Silicon Carbide bench stones here. The sheet is confusing because it lists the composition of the two very different types of stones in a single sheet. John Carmona at Sharpening Supplies provided this link.

How can you build up a slurry using these abrasives?

Waterstones claim as an advantage a weak resin bond holding the abrasive grits. The bonds readily break, releasing worn grit, exposing fresh sharp grit.

The fractured abrasive along with metal filings form the slurry. It is important to keep the slurry wet enough that it does not glaze the stone. The slurry is thought to contain a finer grit (small bits of the original grit) and thus produce a finer surface.

If you use 3M abrasives and baby oil, the slurry of broken abrasive and metal filings is swept away by the blade, collecting outside the area you are using for honing. The baby oil is also swept away and should be refreshed.

Mixing finer abrasives in with the 15 or 5 micron abrasive would only reduce their effectiveness. The 0.5 micron abrasive is so fine that it achieves the smoothing of the final microbevel without the need for finer abrasive particles.

I suspect the waterstone people are selling a fault of their process - the rapid buildup of broken abrasive particles which actually interferes with the microbevel formation process - as a feature.

Steel determines initial sharpness, right?

Of course, that assumes that you use my jig and abrasives and take a little care during sharpening.

So, no matter what blade you own the first few cuts can have a blade as sharp as any blade sold by any manufacturer at any price.

However, you don't do most of your planing with a freshly sharpened blade. For the bulk of your work you want a blade that is durable and that does not fracture at the edge during use. Look at my blade testing results to decide whether you need to get a replacement blade, and if so which blade you should buy.

During use, problems can arise. This is particularly true with A2 steel. Unlike other steels, A2 blades often had fracturing at the edge during my tests. Manufacturers recommend higher included angles for these blades. At higher angles fracturing is much less of a problem, but at higher included angles the blades will not be as sharp either.

While A2 blades seem to require larger included angles than the standard high carbon steel blades, M2 and CPM blades work well with lower included angles. This is important for plane blades used with stringy woods, and for chisels. The lower the include angle the sharper the blade and the better result with softwoods and stringy hardwoods. The lower the angle the less force required to push (or hammer) a chisel through harder woods.

If you have a piece of wood that is best finished with a blade with a final included angle of 25 degrees, then you are probably better off using an O1 or W1 steel blade than one made with A2 steel, but M2 is still a much better steel.

What is the best steel alloy for woodworking tools?

1. What about metal alloys used in edge tools?
2. Do some steels produce sharper edges that others?
3. What are the most wear resistant steels?
4. Why do some steels chip at the edge during use?
5. What is cryogenic treatment and how does it help?
6. How much more difficult is it to sharpen a hard blade?
7. How much does sharpness matter?
8. How much longer does the A2, D2, M2 edge really last?
9. So, is it worth spending the extra money on a harder blade?

1. What about metal alloys used in edge tools?

   Steel, an alloy of iron and at the very least carbon, has been produced in commercial quantities for use in tools for 250 years. Early steel composition was often a proprietary secret, with companies advertising the properties of their particular alloy recipe. Today, tool makers rarely make their own steel. Instead, they make use of the steels readily available in suitable shapes and sizes. All steels now conform to fairly rigorous specifications on the percentage of various alloys. New recipes are being developed all the time, as well as new manufacturing techniques. The grades of steel in this table is representative of those in use today. [These appear to be average values in some sense, with different web sites given slightly different values, or ranges, from some of the constituents.]

   Class	Code	Carbon	Manganese	Silicon	Chromium	Vanadium	Tungsten	Molybdenum
   High Carbon	01	0.95	1.20	0.3	0.5	0.2	0.5
   	W1	1.0	0.35	0.35
   	L6	0.75	0.70	0.25	0.80			0.30
   	A2	1.0	0.6	0.3	5.2	0.3		1.1
   	D2	1.5	0.4	0.4	12.	0.95		0.9
   Stainless	F2	1.3	0.25	0.25	0.3	0.25	3.5	0.3
   	440A	0.75	1.00	1.00	17.0			0.75
   High Speed	M2	0.83	0.275	0.325	4.125	1.85	6.4	5.0
   	S390	1.60			4.80	5.0	10.5	2.0
   	CPM3V	0.8			7.5	2.75		1.3
   	T15	1.55	0.4	0.3	4.5	4.75	12.5	1.

   
   [L6 -- used in band saw blades and user make carving knives -- includes 1.5% Nickel.]

   [440A - commonly used Stainless Steel for knives, includes up to 0.5% Nickel.]

   [S390 - powered metallurgy, includes 8% Cobalt.]

   [T15 is a microfine powder super high speed steel and includes 5% Cobalt. It would probably not be used for hand tools.]

   Different alloying elements provide different properties to the steel. Some of those properties are important in how the steel behaves in use, some how it behaves during the manufacturing process (how consistent the result is).
   
   

2. Do some steels produce sharper edges that others?

   Sharpness is a key property of a woodworking tool. If you can't get it sharp it does not matter if it is tough or durable.

   This question is best asked and answered in two parts. First, for a given set of sharpening angles, is there one steel alloy that can be brought to a keener edge than any other? The short answer is no: commonly available (but not all) abrasives can bring all of these tool steels to the same sharpness. If you want the long answer, go back a bit in the FAQ.

   Second, can some tool steels be used with smaller included angles. In other words, can some tool steel be used in a sharper state. The answer is yes. Most of my tests use a standard sharpening geometry and all these tool steels work well with those angles. One steel, A2, seems to chip out at these angles, but not at slightly higher angles. One steel, M2, seems to work well with a smaller included angle (about 5 degrees smaller seems to work, testing is incomplete.) So, because M2 is tougher and more durable it can be used in a sharper state.

   The next sections discuss these issues in a bit more detail.
   
   

3. What are the most wear resistant steels?

   Once you have a sharp edge, the next problem is how well that edge resists wear.

   This is exactly the question I set out to answer with my blade testing series of experiments. In increasing order of wear resistance: O1, A2, D2, CPM3V, M2. Variations within a group depending on the manufacturer are small compared to the variations between steel types.

   Greater wear resistance during use means greater effort during sharpening. This is a trade off that I am generally willing to make.
   
   

4. Why do some steels chip at the edge during use?

   The final key characteristic of steels is their toughness - their ability to resist fracturing. While edge tools do not seem to have high toughness requirements - a plane working knot free wood - it turns out that some steels appear to chip at the edge more than others.

   Iron includes hard carbides in softer steel material. The generally accepted belief is that the harder carbide particles may in fact break off. The larger the carbide particles, the more likely they are to break away. Different alloying elements, lower levels of impurities, along with better heat treatment procedures, attempt to reduce the size of the carbide particles, reducing the danger of chips popping off the edge.

   For more chip prone steels, larger included angles (lower initial sharpness) usually reduce the number of chips.
   
   

5. What is cryogenic treatment and how does it help?

   Cryogenic treatments involves lowering the temperature of the hardened steel to very low temperatures (-300 F), holding it there for a specified period of time (24 hours), then raising it slowly, often reheating it (+300 F). The treatment is said to change the crystal structure of the steel, possibly producing smaller or harder carbide particles.

   Some tool makers have found no gains from cryogenic treatment -- no greater wear, and presumably no reduction in the incidence of chipping. Others (must) have (or why would they bother to treat the blade?). Some claim that the cryogenic treatment can help, if the original heat treatment was bad. I have not been able to find the specifics of actual tests, just the conclusions of the blade makers.

   In my testing, the cryogenic A2 blade did perform slightly better than the untreated blades (different manufacturers).

   I have found one research report that uses various techniques to look at the fine structure of cryogenically treated M2 steel. The researchers show that cryogenic treatment changes the size and distribution of carbides. These changes may account for improved wear resistance noted by many researchers. Most M2 used in tools does not get cryogenic treatment.
   
   

6. How much more difficult is it to sharpen a hard blade?

   In my experience harder blades -- A2, D2, M2 -- wear SiC and CrO abrasive paper faster. With fresh 3M microfinishing abrasive paper, all blades appear to sharpen very quickly. However, once the paper is worn, these harder blades sharpen much more slowly. For example, a worn paper that still sharpens an older Stanley blade reasonably quickly, might be very slow on an M2 blade.

   With my jig I use about the front 3" of piece of abrasive paper. After 10 or 15 harder irons on the 15 micron paper I will remove the front 1-1/2" of the sheet. In this way I get 4 or 5 sets of 10 to 15 blade sharpenings in a half abrasive sheet, or between 80 and 150 blades sharpened per sheet. This works out to a penny or two per sharpening.

   The 5 micron and 0.5 micron papers are used up much more slowly.

   However, if you use other abrasives, specifically AlO type abrasives (oil stones, water stones) your experience may be quite different. As long as you hone only a small area near the edge of the blade, these abrasives may do a pretty good job. If you try to work a larger area you may not actually get a fine finish on the edge even after quite a bit of time -- these abrasives are softer, not as sharp, so do take more time. There are stories of Japanese woodworkers spending a long time on their edges. This has two benefits. First, it gives the stone time to remove all the required metal. Second, the abrasive breaks down during the session, producing smaller abrasive particles - essentially taking the blade through a progression of grit sizes. This could be true. I have not seen any microscope pictures of such edges. (I am looking into this effect - a background project.)

   I have done some work with Silicon Carbide bench stones, which discusses the increased effort required to form the primary bevel on harder blades.
   
   

7. How much does sharpness matter?

   I (and others) measure sharpness by pushing the blade into a piece of thread. Seems silly, but this is actually what you are doing when you are planing, except that the thread is replaced by wood cells.

   When you are planing into rising grain (the wood cells angle up in the direction of planing) then the pressure you put on the wood cell is resisted by the wood cells behind. A duller blade means more pressure which means more work but makes only a very slight difference in final appearance (a slightly greater tendency to crush rather than cut the wood fibres).

   When you are planing into falling grain (the wood cells angle down in the direction of planing) then the pressure you put on the wood cell to cut it is resisted mainly by the adhesion between wood cells. A duller blade means more pressure which can result in this adhesion failing and tear out.

   A finisher blade of M2 sharpened to a final front bevel angle of 26 degrees rather than 31 degrees, used only in tricky situations, might give you the durability you want with the sharpness you have to have in final finishing.

   Before you decide to go this route, you should first convince yourself that you can get an M2 (or other tougher steel) blade as sharp as you can get a high carbon steel blade. Properly testing your sharpening technique will mean: buying a blade, sharpening it, planing until it is dull, sharpening it again, ..., repeat.

   Why bother? Your blades last long enough and are sharp enough already. Well, you are right, since you are the decider. It is up to you.

8. How much longer does the A2, D2, M2 edge really last?

   In my opinion, it is possible to bring all these tool steels to virtually the same sharpness.

   In use, the harder steels degrade more slowly than the old high carbon steels in the original blades made by Stanley and others in the good old days. For most use -- that is, for other than the final most important passes -- a blade with a lower wear bevel up to 0.0005" wide works pretty well. Most high carbon steel blades have reached this point after 400 linear feet of Douglas-fir. The harder steels -- A2, D2 -- may last twice as long. The hardest -- M2 -- twice as long again.
   
   

9. So, is it worth spending the extra money on a harder blade?

   If you sharpen a lot and keep your blades really sharp, you might be happy with high carbon steel blades from the classic period. I did not move to A2 blades until I got a CRYO treated Hock A2 blade. The extended really sharp period was worth the extra cost over classic Stanley blades. Once I found M2 blades, I switched to them [Feb 05]. Again, the extended really sharp period is worth the extra cost.

   One justifiably famous plane builder and woodworker, Konrad Sauer has moved back to high carbon steel blades because this tradeoff does not work for him. His reasoning, paraphrased: Suppose I was finishing a large piece. Suppose as well that my M2 steel blade was just a little dull. Suppose further that because it is harder to sharpen M@ I continued using this slightly dull tool. Imagine tearout in this final step. All the sharpening time I had saved would be small compared to the effort to repair this surface. (I can no longer find the blog item on his site, sorry. Perhaps he has changed his mind and gone back to other tool steels.)

   This is a decision you will have to make. You might also think of having a finisher blade - a super sharp blade used only for the last stages of a project and always sharpened immediately after use.

10. Links

    Peter L Berglund has a lot more information about steel, why steel is hard, heat treating O1 and W1 steel here.

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