Cheap thermometer calibration technique?

0.98, about as high as anything else on the planet.

John

Take a look here for some really good facts:

Water = 0.98

Aluminum varies from 0.04 to 0.3 depending on finish, absolutely useless for IR temperature measurement.

AlwaysWrong.

John

You keep posting this link, so why don;t you *read* it?

Water has a thermal IR emissivity of 0.98, about as black as anything gets.

John

Nothing like a little actual data to cut through the fog...

or a little confirmation from them that depends on this stuff for their income...

[...]

Or an oft-referenced expert source.

Thanks again, John. Dave (OP)

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DaveC
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Can you really be that dumb?

If the instrument has a one inch focus, your reflection is hardly going to affect what it reads from the face of a "shiny piece of copper". It will read the copper, and be off be the emissivity factor.

Focus is extremely important in the energy gathered by an IR instrument. EXTREMELY. Do you think the 1000' focus device looking at the space shuttle launch pad would get enough energy to give a calibrated reading if it were focused for 20 feet, despite being 1000' away from the target being measured?

Use some common sense, man.

You're an idiot, and there are NO 1.0 emissivity sources.

I think you need to re-learn what is in the realm of possibility. Try the PDF I posted a link to for starters.

It isn't the gradient across it, it is what it inhibits THROUGH it. It does have good surface quality for high emissivity, however.I merely stated that there would be losses.

Yes.It was me, and a MATTE finish (flat black paint) WILL yield a BETTER surface quality with reference to IR readings than a shiny surface will.

List all the 1.0 emissivity sources you know of.

Unfinished Al, you retarded f*ck.

Aluminum is, in fact, what they and nearly ALL makers of low and medium temp black body calibration sources use for their black body faces.

Mikron does, NIST certifies.

What was that, jackass? The REAL world can't hear you!

They use a big 5 pound ingot of AL with a single rod heater shoved into the back of it. The face gets concentric rings that look like someone threaded the face of it, and then THAT gets painted with the black body paint mentioned in the same PDF YOU quoted from, dipshit.

The gradient across the face is less than 0.1° C from center to about

1/4" from the edge of a 5.5" cylindrical ingot about 3.5" inches thick.

NIST buys them. NIST certifies them for their customers... where does that leave your retarded ass.

Oh yeah... FUCKING WRONG... again.

The high temp sources are refractory media cavities where the instrument look into the cavity through a ceramic tube.

You are lost, fucker.

But it has a very high surface reflection issue, and it gives off a vapor above room temp. Badly as temp increases. IR instruments need precise focal distances to get calibrated correctly.

Nice try, FUCKING WRONG... again.

Get a clue, boy.

The expert source would certainly NOT be john, and the link was from ME, asshole.

Well read it then. Water is 0.98.

John

Then it's the paint that has high emissivity, not the aluminum. The aluminum is just a heat spreader. Copper would be twice as good.

And water is still 0.98, about as black as anything gets. My tests this afternoon showed neither water nor ice is the slightest "shiny" at thermal wavelengths. If it were, its e value would be much less, and my melting ice cube wouldn't have read 0.5C on the FLIR.

John

Use a melting ice cube for zero C, and boiling distilled water (in a clean container) for 100 C.

What part of "close to" do you not understand?

robert

[...]

Are you illiterate? Why don't you look up water in the data YOU provide and see for yourself how shiny it is? Hint 0.98 isn't shiny. 0.98 is about as black as it gets.

robert

In the chart the link to which YOU keep posting here, nothing has a higher emissivity than water.

Which makes water an extremely good choice for a reading on the IR instrument.

robert

I agree that illiteracy combined with extreme stupidity is a tough burden to carry.

robert