Yep!  Lorelei is using mild steel, which over here is usually A36, a grade of remelted scrap that does not have a carbon content specification.  It just has have a minimum tensile strength of 36 Kpsi.  The carbon can vary wildly, but there's never enough for a good blade.  We can also get 1018 and 1020 if we're willing to pay extra for clean, easier to weld mild steels.

Optics study oflight

Reflection is one of the primary properties of light. Reflection is nothing but the images you see in the mirrors. Reflection is defined as the change in direction of light at an interface in-between two different media so that the wave-front returns into a medium from which it was originated. The typical examples for reflection of light include sound waves and water waves.

No, they are not.  Blacksmiths use mild steel, low carbon in in the 0.18-0.25-ish %.  Bladesmithing steels are in the 0.60-1.20% carbon range, which makes a huge difference in behavior.

Definitionof opticsin Physics

May 7, 2018 — This is perspective distortion, and it is an inevitable outcome of projecting a three-d world onto a flat surface.

You don't see us using IR thermometers because they are both expensive and do not work on glowing steel.  They are calibrated for black body emissivity, and if you throw incandescent heat at them they freak out.  That one does spec that it reads up to 2012 degrees F, which is much higher than I have seen on any other unit, but I have my doubts it does so with any accuracy.  When we need to know the temperature we use a pyrometer setup consisting of a type K thermocouple and something to read it with.

Spend some time initially with your steel getting used to what it tells you. For instance. Heating it up initially use a magnet as the steel heats. When the steel stops attracting the magnet, with 10xx series you are in the 1415-1425 F range. Get to know what that color looks like to your eyes in those conditions. Next you want to watch for the decalescence effect. This will be of great importance in the hardening process. Get to know what color, again to you, that occurs at. The next milestone is when sparks come off the blade. In technical terms, for the purpose of forging on  an homogeneous bar, it is called "too frigging hot !" You are burning the steel. Don't do that again.

what are the 3 typesofoptics?

In physics, the term light also refers to electromagnetic radiation of different kinds of wavelengths, whether it is visible to the naked eye or not. Hence, by this, the gamma rays, microwaves,  X-rays, and radio waves are also types of light. Learn more by visiting the links below.

Fourier optics is a useful tool for studying optical systems. Some phenomena, such as the photoelectric effect, can be explained only by quantum optics, and ...

To put it in simple terms forging should happen in that zone between ""tfh" and when it cools to the point it stops moving readily under the hammer. Your reading should have told you the effects of forging too hot or too cold.

Like all the different types of light, the spectrum of visible light is absorbed and emitted in the form of tiny packets of energy called photons. These photons have both the properties of a wave as well as a particle.

Many years ago I was a test engineer in an elevator manufacturing plant.  I got into an argument with a design engineer over a new product were were making.  There was a shiny (reflective) copper plate in the product that I was concerned was getting too hot.  This guy came out with his IR temp gun and told me there was no issue, that it was only 120F.  You could see the heat (and smoke) coming off of it, so I told him to touch it if he felt his measurement was accurate. (He declined)  The guns are tuned for something that has an emissivity near 0.95.  (A perfect black body is 1.0) A shiny surface will be much lower.  If I remember right, I back calculated that the copper must have been closer to 0.3, but that was 20 years ago.

Unless you have a glowing version right next to your forge, no, it isn't really that helpful.  That was my original point.

Going back to the original post, one thing nobody has addressed (although Mr. Giagni came close) was the question of whether the steels in the blacksmithing book were the same as those in the bladesmithing book.

Typesof optics

The "IR guns" do have their place, and I actually own two of them.  I keep one in the kitchen to check the temp of my cast iron frying pans before the food goes in, and I use another to check the shell temps of my pet tortoises.

Going back to the original post, one thing nobody has addressed (although Mr. Giagni came close) was the question of whether the steels in the blacksmithing book were the same as those in the bladesmithing book.

This first image is the object for the second lens, or eyepiece. The eyepiece is intentionally located so it can further magnify the image. The eyepiece is ...

I'm a little confused - I've been reading "The Backyard Blacksmith" as well as "The Complete Bladesmith" (referred by this forum) and both authors refer to the most effective "temperature colour indication" for mild steel. However, Lorelei Sims says "forging is most effective when the metal has turned yellow"(2100°F)... while our friend Jim Hrisoulas says that "most of the carbon steels" beginners will use should be worked at "the cherry red range" (1500°-1800°F). I'm fairly certain they're considering the same steels so what is up? If I'm just starting with 10 series steel what guideline should I use?

Optics study ofrefraction

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Then there are the other alloying elements we use that blacksmiths do not. Our steels have more manganese, chromium, vanadium, silicon, tungsten, nickel, and other fun things that can cause problems if forged too hot or too cold.  Problems like turning into the steel equivalent of cottage cheese when too hot, or filling with microfractures when too cold.  With mild steel all you have to worry about is burning or breaking at higher and lower temperatures than we usually use.

Ahhh... thanks! That would explain the difference..they both used the same terminology and didn't seem to contradict each other at any other point. Odd though, I went back and looked and while Jim mentioned 'carbon steels', Lorilei never mentions what particular steel she is working with in that section.

Optics study ofphysics

TM-202 - Digital Light Meter FC/LUX.

And those in between are in between.  Generally, colors aren't a great guide, because my definition of "cherry red" is going to be different from yours (and likewise from everyone's), and ambient lighting skews things.  Personal experience, especially with a knowledgeable guide present, is going to be your best guide.

You don't see us using IR thermometers because they are both expensive and do not work on glowing steel.  They are calibrated for black body emissivity, and if you throw incandescent heat at them they freak out.  That one does spec that it reads up to 2012 degrees F, which is much higher than I have seen on any other unit, but I have my doubts it does so with any accuracy.  When we need to know the temperature we use a pyrometer setup consisting of a type K thermocouple and something to read it with.

Hence this type of property is called wave-particle duality and the study of light in the area of physics is known as Optics.

That is the tempering color chart I was referring to (note that it only goes up to 600F).  The OP was asking about forging temps.  Do yourself a favor and forget that the chart you found even exists.

The rate at which the light travels in free space is called the Speed of light. For example, light travels 30% slower in water when compared to vacuum.

When a beam of light strikes the water, a part of the light is reflected, and some part of the light is refracted. This phenomenon is called as total internal reflection. Read More: Total Internal Reflection.

Feb 13, 2018 — Angular field of view can be used to calculate the linear field of view: just multiply the angular field by 52.5. For example, if the angular ...

Optics study ofmatter

by S Zhang · 2023 · Cited by 11 — The modulation transfer function (MTF) is an important parameter for performance evaluation of optical imaging systems in photogrammetry and ...

I had the chance to play with an IR gun that was supposed to work on liquid steel.  You had to determine the emissivity constant for that grade, but once you did that and plugged it into the unit it worked fairly well.  Until smoke or slag got in the way.  Which it did.  Constantly.  And that gun was $30,000.

With its stylish arch metal frame and delicate wood crown detailing, this mirror adds a touch of sophistication to any space. Perfect for entryways, living ...

I get about as irritated when people use these things as Jarrod does when people talk about tempering colors.  I have seen them be 200% off with surfaces that had emissivities that were odd.

Ray optics is also called geometrical optics. It is a branch of science that describes light propagation in terms of “rays”.

Lastly, I don't have a lot of equipment and tools, but one thing I do have access to is a Temperature Gun as shown here: http://www.reedinstruments.com/product/reed-r2007-dual-laser-infrared-thermometer        I'm kind of shocked I've not seen it used before in any of the online videos or instructionals, but I thought, as a beginner, it might help me pinpoint these 'colours' more effectively...at least starting out.

Observation and experience are far more valuable than color charts since there are too many variables involved that affect color both to an individual's perception and in individual environments.

As Alan said, the inaccuracy gets worse once the surface is incandescent. There are optical pyrometers out there that are supposedly good for glowing materials, but I haven't had the opportunity to use one yet.  The ones I have seen for sale are quite expensive.

It is a property of light, where the white light splits into its constituent colours. Dispersion can be observed in the form of a prism. The other properties of light include diffraction and interference. So, what do you observe when you look out at the beautiful scenario? Whether the light gets reflected, dispersed, refracted, internally reflected, or diffracted.

"The Backyard Blacksmith" mostly deals with mild steel which can be forged a lot hotter than the steels used for knives.

Optics study ofchemistry

Optics is a branch of physics that deals with the determination of behaviour and the properties of light, along with its interactions with the matter and also with the instruments which are used to detect it.

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And before you get to tempering: please ignore temper colors.  They are not accurate enough.  Get a method of using thermal mass and an accurate thermometer.

Wave optics is the branch of optics that studies the diffraction, interference, polarization, and other phenomena for which the ray approximation of geometric optics is not valid.

Optics, in a simple manner, is used to describe the behaviour of visible light, infrared light, and ultraviolet. Imaging is done with the help of a system called an image forming an optical system.

No, they are not.  Blacksmiths use mild steel, low carbon in in the 0.18-0.25-ish %.  Bladesmithing steels are in the 0.60-1.20% carbon range, which makes a huge difference in behavior.

Light is a form of energy that is in the form of an electromagnetic wave and is almost everywhere around us. The visible light has wavelengths measuring between 400–700 nanometres. The Sun is the primary source of light by which plants utilize this to produce their energy.

The bending of light when it passes from one medium to another is called Refraction. This property of refraction is used in a number of devices like microscopes, magnifying lenses, corrective lenses, and so on. In this property, when the light is transmitted through a medium, polarization of electrons takes place which in turn reduces the speed of light, thus changing the direction of light.