Unlucky with CPC IR-88 infrared thermometer

[Codswallop]

I have tried two of these and returned both as faulty as there was not a peep out of the laser light:

sod the laser, I have ordered this instead:

[Fred]

boiling water in, point your fancy gadget at the saucepan and see what temperature you get!

[mrcheerful]

You need a matt black surface for an accurate reading.

[Fred]

Hmm - try looking at a black (non shiny) anodised aluminium!

The fact it may look black to you doesn't mean it looks black in the far infrared. BTW many white surfaces look "black".

Thankfully most plastic surfaces including paints (and white paint) look black in the infrared. Just that you need to be careful, there's a lot of misinformation about!

[John Rumm]

To be fair, I find I get a decent reading off any non metalic surface. To read from unpainted metal I just stick a bit of tape on it and take a reading from that.

[Codswallop]

I am intending to balance my radiators, not conduct emissivity experiments in my kitchen! I know what you are getting at, and I know that what you suggest will not result in an accurate temperature readout.

"Shiny or highly polished surfaces can be very tricky to measure, even dull smooth metal surfaces may not be equally emissive in all directions. Be especially careful where surfaces are highly curved, see viewing angle above. If the emissivity is very low, some polished surfaces have an emissivity of 0.2 or less, then an accurate reading is unlikely to be possible."

"Masking tape or matt paint applied to a part of the surface can be used to give an emissivity of close to 1.0. Generally the colour of the tape or paint has no effect."

Source:

[Andrew Gabriel]

Most surfaces you are likely to use it on are near enough matt black in the infra-red that it doesn't matter, except it doesn't work on bare copper.