This is part two of an article that originally appeared in the magazine on historical arms and armour ‘Broń i Barwa’, which was published in Poland in the 1930s. THE GLADIOLOGICAL regularly re-publishes decades to centuries old outstanding works by the best authors in carefully hand-translated form.
Read part one by clicking here.
The images (all of them show objects with parts of Damascus steel/Bułat) are not part of the original article but are provided by the MNK in Kraków. Thanks to institutions like the MNK which make their online databases public domain, projects like The Glad can enrich the transfer of knowledge with beautiful images of antique arms and armour. You can find a link to the MNK below in the sources appendix.
Crucible Steel, Part II
by Jerzy Podoski
First published in Broń i Barwa Issue III, Warszawa 1934 , Wydawnictwo: Stowarzyszenie Przyjaciół Muzeum Wojska
Anosov was convinced that the pattern on the blade (also visible on the disc before forging and on the slag during melting) demonstrates the degree of carbon saturation and thus also the quality of the steel.
He established the following grading of blades according to the pattern:
– Longitudinal waves, parallel pfawls: inferior blade, shortly melted and quickly cooled.
– Twisted waves: a better melt.
– Twisted waves, passing into lattice: high grade bułat,
– Waves form regular steps and clusters: the highest grade
This classification is in line with that of the Persians, who placed the stepped bułat first: ‘kirk nar- duban’, while in last place was the weak-wave “sham”.
There are two more factors, proving the quality of the blade – these are the background colour and the brilliance.
Anosov states that the more glassy the slag during melting is, the whiter the background of the metal. On the contrary, as the slag darkens, so does the metal. The backgrounds can be grey, bronze and black. Bułat-steel can have a golden, reddish or more or less colourless lustre. The more pronounced the lustre and the closer its colour to that of gold, the more valuable the blade.
Putting the above remarks together, the following observations by Anosov regarding the relationship between quality of the blade to external characteristics can be summarised:
a)
The size and brightness of the pattern on the blade indicate the amount of carbon absorbed by the steel, while the distribution and shape of the pattern indicate the different degrees of perfection of the iron-carbon compound.
It is likely that the carbon content of the coarse-patterned bułats is up to 5% (equal to the carbon content of the pig iron), and that of the fine and faint-patterned bułats is around 0.5% (similar to that of steel).
b)
The colour of the background of the bułats and of the patterns themselves indicates the purity of the iron and carbon used in the alloy. The darker the background and the shinier and brighter the patterns, the purer the ingredients.
c)
Only the gold-coloured bułat is the result of a true junction of C with iron (ancient taban and chorassan).
d)
Reddish-coloured bułats contain foreign admixtures (kara-taban).
e)
Glareless bułats contain C in the form of ordinary carbon. With a large amount of carbon, these bułats are sometimes very brittle (some kara-chorassan).
The issues of forging, hardening, polishing and etching of objects made from bułat were also studied by Anosov.
The blades created by Anosov had extremely high mechanical values. The researcher says the following about the testing of his blades: ‘A smallsword blade made of good bułat, properly ground and hardened, cannot be broken or bent to the point of losing its elasticity. If it is not bent too far, it straightens itself; if it is bent too far, it needs to be straightened at a right angle, but then it does not lose its elasticity. Thanks to these characteristics, a bułat blade can be hardened more strongly than a steel one’.
Anosov was able to easily cut through a silk gauze handkerchief thrown in the air with his bułat blades, while this could not be done with the sharpest blades made of English steel.
Other trials have shown that the best English blades can be crushed by the use of bułat.
Anosov’s experiments were repeated in 1864 by Professor Chernov, who succeeded in producing light-coloured, slightly wavy bułat blades.
F.
Critical remarks
In spite of the extensive and apparently thorough work cited above, the issue of Damascus or bułats must be considered as not being conclusively resolved. This is evidenced by the following reflections, which suggest themselves to the reader who is somewhat more familiar with metalworking issues….
1.
Gen. Anosov, working in the years: 1830 – 1850, did not yet dispose of modern means of chemical analysis of metals and metallography. Professor Chernov, on the other hand, had full use of these means (around 1900). Why does he not give a single result of the analysis of the composition of steel (it is mentioned that the carbon content of bułat is probably between 5% and 0.5%) and not a single work on the microscopic examination of grinds? The difference between a steel containing 5% carbon and another containing 0.5% is so enormous that one material cannot be directly compared to another.
2.
Let us not forget that Anosov was working on the height of the Romantic period and its highly false and exaggerated attitude to old, heirloom things, and old weapons in particular. It was a kind of exaltation, highly detrimental to scientific research. Perhaps this mind-set could explain Anosov’s extremely optimistic attitude towards the value and quality of eastern steel.
3.
Any researcher of Damascus blades knows well that a characteristic of all these blades, even the most beautiful and the best, is their lack of elasticity, their brittleness and especially their tendency to longitudinal cracks.
While broken or cracked damascus blades are very common, broken or longitudinally cracked blades made of good European steel, not overhardened, such as Châtellerault sabre blades from France or Zlatoust blades from Russia, are extremely rare.
4.
If bułat blades had such a great advantage over those from European-style steel, the people of the East – Indians, Persians, Caucasian highlanders – would undoubtedly use only bułats, rejecting European blades with contempt. Meanwhile, we see quite the opposite phenomenon: many European sword blades- starting from the Middle Ages – set in the best and most expensive Eastern fittings, which clearly proves that they were highly valued. In the Caucasus, which shares a border with Persia and where the best Damascus were probably easy to come by, we find almost exclusively steel blades, and the most highly valued are 16th century Solingian (Volchok) or Genoese (Gurda) ones – or their forgeries made by Caucasian armourers, sometimes better than the originals.
5.
The author (Belyaev) claims that forged damast blades are only imitations of bułat blades produced my melting, and have much lower values; besides, he attributes the first attempts to produce European forged Damascus to Prof. Crivelle at the beginning of the 19th century. In the meantime, we have good European forged Damascus from the 18th century of the Solingen manufacture (the oldest known to us bears the authentic date of 1710), these Damascus are extremely resilient, strong and not at all brittle, their value is superb. In the East, however, we find Damascus blades everywhere in weapons which require great strength and material resistance: in knives and daggers for piercing chainmail.
6.
P. Belyaev mentions attempts, made with blades from the Eastern bułat, and Anosov’s work, however, we must consider these attempts as highly inadequate. Much is said about cutting through a silk handkerchief thrown in the air-but can we consider this to be an adequate examination? This is evidence of an excellent sharpening of the blade and of its good construction, but the obstacles which the sabre faces in battle were, and remain, completely different – the quality of the sabre must consist less in its great ease of sharpening than in its perfect shape and balance, ensuring maximum cutting power, and, as for the steel itself, in its sufficient but not excessive elasticity, the least possible brittleness, and so on.
Suitable tests were very strictly and properly formulated in the receiving conditions for sabres at Zlatoust, and it would be highly interesting to carry out such tests with bułat blades. However, it is likely that few blades would withstand such trials.
7.
As far as the bułat pattern grading is concerned, there are also some criticisms: the authors repeatedly emphasise that the thicker patterned bułats are higher in C content. Meanwhile, practical knowledge of eastern weapons seems to indicate quite the opposite, namely:
a) Blades, apparently the most ‘luxurious’ ones, belonging to rich people, to ‘the mighty of this world’, decorated with gold inlays, stones, etc., always have an extremely fine pattern. It is easy to see this in any large collection. Blades with a coarse pattern are almost never decorated.
b) Armour and helmets, which should be extremely hard and resistant, are made exclusively of extremely fine-patterned bułat. Such steel is in fact usually extremely hard (it resists modern files effectively), but is much more brittle than an Eastern sabre blade. This bułat, therefore, contains more C, contrary to what is claimed by authors, who, by the way, did not do any analysis.
c) The Persian and Afghan short knives, with their strong pointed blade, designed for piercing chainmail, are made of extremely fine damascus. It is obvious that the values required of these weapons in terms of sharpness, strength and unbreakability are very great.
8.
Finally, the issue of the colour and brilliance of the blade. After ‘revealing’ several dozen (about 60) bułat patterns on blades of the most varied types and designs, after conducting tests with different acids and with different acid solutions, we have come to the conclusion that the only thing that varies is the degree of ease with which the blade darkens under the influence of acid. Some rolls darken very quickly and reach a grey-black colour, while others darken very hardly and slowly and acquire a general dirty-grey colour.
On the other hand, brilliance and the ‘colour of brilliance’ depend to the greatest extent on the method of chemical pattern revealing – on the means used. It has happened to us twice that a blade with the famous and allegedly most valuable golden lustre – after being thoroughly polished, acquired its normal colour of very dark grey or almost black when revealed again. After some attempts, however, we were able to obtain a golden colour on other blades by using a weak solution of hydrochloric acid, which, by the way, has the great disadvantage of colouring less than damaging the surface of the steel and making it too dull.
G.
Revealing the bułat pattern
The procedure consists of coating the blade with acid to obtain a colour reaction in which the hard parts (carbon steel) are more difficult to colour and the soft parts (iron) are covered with a layer of salt: iron sulphide, chlorates or nitrates, and darken to black, greenish, reddish, golden or grey.
Here it is important to distinguish between two separate types of blades.
a) Blades with a large difference in the reaction of the individual molecules to the acid – these are the blades that only need to be ‘stained’ with a weak acid -‘ these include Persian and Indian blades.
b) Blades with a very small difference in colour reaction between the individual steel particles – these blades cannot be ‘tinted’, as they turn grey or black and lose their pattern, and must be deeply etched.
The treatment is fundamentally different, depending on the type of blade we are dealing with.
In both cases, it is necessary, first and foremost, to grind and polish the blade with the greatest care, so that the entire blade is flawless, without a single blemish and with the uniform shine of a good modern mirror. We would also like to point out that today’s grinders, working carelessly and quickly, have a tendency to polish without first grinding well. As a result, the blade shines very beautifully, but has many blemishes which do not disappear sufficiently after polishing, but which come out most brightly and spoil the entire shine immediately after the acid coating.
The second step is to degrease the side we intend to etch first, and to apply a strong smear of grease or, better still, wax to the opposite side to avoid runs and stains.
Degreasing is carried out as follows:
- A couple of washes with ether, benzine or spirit on cotton wool.
- Thoroughly dry.
- Sprinkle talcum powder all over the blade, thoroughly wipe off the talcum powder with cotton wool.
- Coat the blade again with talcum powder and spread the talc so that the entire blade is coated with a thin but even layer of powder.
The blade is now ready for acid coating and we proceed with this operation.
We normally use 5 – 8% sulphuric acid (5 to 8 cc. of pure sulphuric acid per 100 cc. of tap water at about 30° Celsius).
Equally good, although slower acting and often giving stains, is lemon juice.
Pour the liquid into a bowl, take some cotton wool in wooden tongs (for drying photographs or underwear) and coat the whole blade evenly with the liquid. Due to the presence of talcum powder the liquid should spread easily and evenly without any symptoms of running drops. Insufficient talcum coating seems to be a common reason for problems making the pattern visible later.
(Sulphate acid in such a solution does not present any danger to the skin, however, as it stains slightly and can cause minor damages on the epidermis under the nails, wooden tongs should always be used).
Every few minutes, move the soaked cotton wool again over the entire blade, so that the liquid does not dry out anywhere and no crystals form.
There will now be features on the blade that will determine the further procedure:
a)
If the pattern on the blade remains clear and shiny and the background slowly turns dark without blurring the drawing, and the whole image remains clear and clean, we are dealing with a Damascus that only needs to be stained and the pattern reveal is completed in this way. Then – without rubbing off the acid – we wash the blade under a strong current of water, without touching it with our hand, with a cloth or brush, without rubbing off the water, as quickly as possible, but lightly covering with a layer of vaseline. The lubricant pushes off the water and the whole blade becomes greasy. In this state we leave the blade for at least 15 minutes, then the lubricant is lightly rubbed off and the blade is polished with a flannel or suede cloth. The issue of lubricating after washing without wiping is essential to achieve a beautiful shine. On the other hand, alcalization or otherwise neutralising the acid after development is not necessary, as the acid is so weak that it stops working as soon as it is washed off with water. Alcalization would only cause a loss of brilliance.
b)
If the blade first highlights the pattern, but then ‘blurs’ very quickly, and takes on a black or bronze colour, and the pattern disappears, this is evidence that the two types of metal from which it is made are not very resistant to acid and colour to an almost equal degree. (This is how soft blades behave). In this case, the staining method will not give results and a weak etch is required. Continue with the same acid until completely darkened, then wash with a soapy brush, wipe dry and ‘de-etch’ the blade to remove any metal sulphides, so that the parts that were more over-etched become slightly concave. This can be done either with a strong sulphuric acid (difficult and requires practice) or with Spiess’ Deoxidin, which is much weaker but very effective. After the first washing, the pattern will barely be visible, however, after a few coats of acid and washing, the drawing will appear convex and very clear. When finished, the blade should be lightly polished with Viennese chalk on a buffing wheel.
c)
If the pattern appears on the blade in only a few places, and the metal does not darken almost completely, but only turns slightly grey, this proves that we are dealing with a blade that is exceptionally acid-resistant, in which both types of metal are only slightly discoloured by the acid. All forged Damascus and most Turkish Damascus react in this way, predominantly on wide, short blades falsely called “scimitars” (Kiilidż). Such a blade should be etched with strong agents.
We wash off the sulphuric acid, wipe the blade and, without greasing it, cover it with a layer of pure hydrochloric acid. This operation should be performed either outdoors, in the wind, or in a very well-ventilated place and in the presence of a breeze, because the fumes of hydrochloric acid are extremely unpleasant and harmful to the respiratory tract and eyes. Using a normal gas mask with a combat absorber eliminates all danger.
After the blade has turned black, wash it off as before, etch it with acid again, etc. until you get a convex pattern. It is better to wash it off with sulphuric acid, because hydrochloric acid stains steel strongly and permanently. After finishing the development, wash it off thoroughly with sulphuric acid, then with soapy water using a hard brush, and finally with a cloth with soda or ammonia and grease it thoroughly. Watch the blade for a few days to see if it rusts. Finally, polish it with very fine emery and Vienna chalk.
THE GLADIOLOGICAL points out that the team members have little or no prior testing of the methods mentioned, and that working with chemicals is always dangerous. We assume no liability for damage to property or people resulting from the application of this information.
Sources:
Article: Broń i Barwa Issue III, Warszawa 1934 , Wydawnictwo: Stowarzyszenie Przyjaciół Muzeum Wojska
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