Science Friday

You-all regular readers might remember when we put in the grid for the radiant floor in the studio last fall (September 21, 2007 blog entry if you don’t happen to just recall that). It’s taken a while to get things into a condition where we could test that grid. We knew from the inspection and the pressure testing at the time that the pipes had no leaks. What we wanted to test was the flow of heat through the system.

Through persuasion and the extraordinary good will of our Neil Kelly company liaison, we acquired the loan of an infrared camera on Friday. Just at the outset, let me say how far this camera is from my previous experience with infrared photography. I can describe to you the pains required to make infrared images on film. That was in the mid-1970s when I was a graduate student in Anthropology at Portland State University. We wanted to make some infrared photos of rock paintings in the eastern Oregon desert, thinking that portions of the designs not visible in normal light might show up in the IR images.

The film itself was not terribly costly as I recall. I’d have noticed if it had been. This film, Kodak High Speed Infrared (HIE) black-and-white negative film, is sensitive to light wavelengths in the “near infrared” range: 700 to 900 nm. kodak_hie_box.jpg Infrared film is also sensitive to any kind of warmth (light is heat), so it needs to be kept cool if it is not to fog before you intend to use it. Since we were going to the desert with it, we packed it into a cooler with ice. Also into the cooler went rubber gloves, like the dish washing kind, to insulate our warm fingers during handling of the film.

The camera must be loaded and unloaded in total darkness, so we bought a changing bag, which did seem expensive. A changing bag is a heavy cloth bag, usually of more than one layer of cloth, with a doubled-over closure on one end to allow you to put the camera and film inside and close it up against light. The other end of the bag has sleeves that work backwards: the elastic cuffs go up on your arms and your hands go inside the bag where you use tactile memory to open the film box, open its inner wrapper, extract the film canister, open the camera, orient the canister the right direction, install the film into the camera and onto the take-up reel, and close the camera. The emulsion on HIE film is fairly tender as I recall, and it’s easy to damage the film with scratches, so you try to be careful. But you perform this operation wearing rubber dishwashing gloves that have just come out of the cooler, you do it quickly, and you put everything back into the cooler.

The other thing required for IR photography on film is a dark red filter, and that was expensive. Yowie. I settled for a very dark red #29 gelatin and a well-used filter holder instead of a threaded glass filter. It was still expensive. The purpose of the filter is to block blue wavelengths and pass only the red ones.

One other thing: Infrared radiation does not focus on the film plane in the same way as visible light. The IR wavelengths are longer and the focus point is further from the camera lens. The lens has a little red dot on the focusing ring that tells you where the IR image will be sharpest. You focus normally by looking through the viewfinder and turning the ring. Then you look at it, and move the ring so the dot lines up where the normal focus marker was.

One other other thing: normal ISO ratings don’t apply to IR films because they respond to heat. So you guess a lot, and just take a whole bunch of different value exposures.

Off we went to the desert with our cooler and things, and set ourselves up to go to work.

The plan was this: we thought we would overlay (at that time, by means of tracings) visible light images of the paintings and IR images, and get really neat enhanced views of ancient drawings. A pictograph is an image made by the application of pigmented material to a rock surface (a petroglyph, on the other hand, is one made by incising the surface of the rock). Some pictographs are magnificent as they come to us, like this painting of an elk on rocks near The Dalles, Oregon (this one is shown on the website of the Marysville Pictograph Project

Elk pictograph, The Dalles, Oregon

But many are mere traces of color on the rock.


Since pictographs are created using earth pigments for the most part, mixed with binders that might be of vegetable or animal origin, we thought we might be able to pull out images of some of the binder material where the pigment itself had faded or eroded.

Our first problem, after loading the camera, was: the cooler was not “a cool dry environment.” It was a cool, damp one. In fact, by the time we arrived on-site, it wasn’t even very cool anymore, since the ice had melted and was swishing around in a leaky plastic bag. About the second time we brought the camera out, everything was covered with little droplets of moisture: camera body, lens, and, we presumed, the film inside. So we waited for it to clear, knowing that the temperature was rising on the film the whole time. We fiddled with the tripod, we dropped things, we shot frames and frames of vaguely visible smears of color on hot rocks, taking far too much time to put and take the dark red filter between focusings and resettings of the focus point. I don’t remember how many rolls of film we shot, awkwardly unloading and loading film in the changing bag. I do remember that when we got it all back from the lab, we didn’t have any pictures that were useful at all. We had a lot of images of really hot places, some scratches, and a great deal of static scatter on the film.
I recently came across this notice from Kodak:

—Notice of Discontinuance—

Due to declining demand, KODAK High-Speed Infrared Film / HIE has been discontinued, effective YE 2007.

I wonder why?

OK. We return to the early 21st Century. On Friday evening I came home with the loan of an incredibly expensive digital infrared camera to use in measuring the flow of heat through the array of pipes in the floor of the studio. Here is Richard with the camera:

Digital Infrared imaging


You do have to focus the thing, but that’s about all except to point and pull the trigger. And when you do, this is what you get:

Yellowcat in infrared

That’s Yellowcat, outside the camera, and inside. Or, inside my camera, but outside the IR camera, and inside it.

After entertaining ourselves with looking at our cold noses and ears and such, we settled down to the science of the matter. We stuck little numbered markers all over the floor at intervals. 08mar_ir4_cr_sm.jpg

You can tell by the photos the light was fairly low in the Laboratory. We found that the ceiling lights were enough to give a higher temperature reading to the floor beneath them.

After marking the floor with a back-and-forth of numbers, we measured each location with a laser-beam-looking IR thermometer. Imagine this. An infrared camera and thermometer, and two sheep-raising, tree-hugging dirt worshippers using them.

Then we turned on the water to the system and went away for an hour.

When we came back to take new measurements at each location and look through the IR lens, this is what we saw:


You are looking at an infrared view of a section of the floor with warm water running through the pipes beneath the concrete. The black snake is an electrical cord, and the black lump in the corner is a vacuum cleaner. And you can see an absolutely even flow of the heat throughout. This made Richard smile a lot. Big smile. You see, this grid, with water entering through a supply manifold (on the far right in this picture) and back through a return manifold (the second, inner warm (white) vertical line on the right side of the picture) after a brief run through the horizontal distribution lines, is Richard’s design. He and Monty decided to install it experimentally, because the radiant floor man wouldn’t do it — in a normal system the water enters at one end, serpentines through the floor, and exits at the other end for return to the supply. The result is a floor that heats unevenly because heat is lost as it flows through the long line to its exit. Eventually it catches up as the whole floor heats, but the Moore-Yarnell (handsome first billing is alphabetical only!) manifold gives a more even flow of heat from the beginning. If you look at the center of the camera display, you see a little rectangle with a dot in the middle. This dot aims a temperature sensor. The sensor is looking at a dark (cooler) area between pipes. In the upper right corner of the display, the temperature there reads 44.7F. That floor was really cold. The white (warmer) areas registered about 2.5 degrees higher in temperature. That’s not a lot of difference to the feet on the floor. To the instrument, apparently it is significant.

Below is the downloaded false color image from the camera. This kind of imaging is used to make more obvious the small differences that might be recorded by the camera. Here you can see the two manifolds quite clearly on the right. And you can see  how really cold it was at the still uninsulated walls further right and the sliding glass door at the top.

False color rendering

We felt very scientific as we logged the temperatures at each marker. It’s nice to use your college education for something, even if it’s only an excursion into scientific method:

Make observations (That floor doesn’t heat evenly.)

Form a conjecture (There must be a better way)

Do research (Specifically, that’s a lifetime of seeing how it works.)

Think about it and make a prediction (If the heated water makes a shorter journey before returning to the source, it will lose less heat, and will heat the floor more evenly.)


Analyze results.

Make a report (and return the camera!)

Smile, smile, smile.

Ibn al-Haytham

This is Ibn al-Haytham, polymath and an early proponent of the Scientific Method. He lived from 965 to 1039 in Basra of modern Iraq, and is honored by his picture on the Iraqi 10,000 dinar note. And here below is his moon crater, Alhazen.

Alhazen crater

If you’re good enough at doing science, you get things named for you. Maybe someday there will be a Moore-Yarnell Manifold crater.

Published in: on March 18, 2008 at 10:25 am  Comments (2)  

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2 CommentsLeave a comment

  1. I stumbled across your blog entry looking for infrared photos of hydronic heat systems. Excellent application of the scientific method to solve the problem of uneven heating by shortening up the loop lengths and lengthening the distribution path. Enjoy your warm floors!

  2. This is really cool.

    I replied to your comment in my own blog, but I clicked back over here and got sucked in by Science Friday! I worked a little bit with black and white infrared film in high school photo classes, but not for scientific purposes.

    Serendipitous, as well, that you’re in Oregon – I’m thinking of moving to Portland at the end of the summer. I realize I’m a total stranger, but I’d love to hear some more reasons for moving up that way, if you’d be willing to share. Send me an email at hikuwai(AT)gmail(DOT)com. If not, that’s fine too. 🙂

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