OT: Infra-red camera capabilities?

I'd call up the applications guys at FLIR. If there's any publicity involved, maybe the marketing guys would provide the equipment.

+1

I wonder how FLIR might work, since the message is buried under wallpaper and maybe paste and/or other materials.

I realize that black objects absorb radiant heat more readily, although the black paint is embedded and likely to be a very thin segment of the overall materials making up the wall. I think the message would be extremely difficult to read unless the black paint had some special characteristic such a radioactivity, etc.

The Agema thermal camera I have, only senses differences in the temps of the first surfaces exposed to the camera.. any covered or otherwise obscured hot/cold spots aren't picked up. Warm and cool areas of a wall, for example, aren't well defined, definitely not capable of reproducing text.. the warmth spreads out into subtle areas, not sharp lines.

Being able to detect the area of the hidden message might not be impossible, but being able to read words of (maybe) 1" letters would probably be unlikely.

There are commercial wallcovering materials which are much more durable than simple "paper" types.. maybe the stuff could be carefully released (heat, solvent etc), then reglued to restore the appearance of the wall.

--
Cheers, 
WB 
............. 


"mike"  wrote in message  
news:l9nipr$jef$1@dont-email.me... 
> On 12/28/2013 10:19 AM, N_Cook wrote: 
>> For academic reasons it would be useful to read some hidden script on a 
>> wall that has been papered over with thick and profiled Anaglypta type 
>> wallpaper, ie thicker than ceiling paper or standard wall paper. The 
>> script is supposed to be large lettering of about 1 inch in height and 
>> probably stencilled black paint, applied to the plaster of a wall, since 
>> covered over. Permission to steam off this section of paper is unlikely 
>> to be given but non-intrusive exploration would be allowed. 
>> Assuming a professional IR camera can be borrowed , ie not webcam with 
>> IR filter removed. If sections of the wall were heated for a few 
>> (variable by experiment) seconds with a radiant heat lamp , would it be 
>> possible to resolve a difference between black paint and background 
>> plaster on a IR camera screen, all lying under wallpaper, or any other 
>> ideas 
> I'd call up the applications guys at FLIR. 
> If there's any publicity involved, maybe the marketing guys would 
> provide the equipment.

Thanks for the input, could you go into more detail of the circumstances where a covering obscured underlying hot/col spots? Are you saying a slightly warmed object under a room temperature sheet of thick paper would show up ,but if the paper was heated to a higher temperature than anything underneath, then only the effect of the covering would show, masking any lower temperature underlying object?

Background - I got involved with an academic researching tides, now 3 academics because of confusion in the historical record. Nothing to do with the research involving a pub ;-) There are current official publications with erroneous data in them relating to tide heights. Tide heights get increasingly confused over time, use of Ordnance Survey datum, Chart Datum, both change over time, rising sea levels and (locally) falling land levels and then GPS to add to the confusion. So with loss of records of what datum was applied at differnt times and places there is a lot of confusion/misinformation. What really matters for local flooding issues is the height of extreme tides at one spot over a long period of time, whether that spot of land rises or falls or seas rise generallly in level, is immaterial. There is a pub at Cowes, on the Isle of Wight, England, the Vectis Tavern that used to have the levels the tide reached when it flooded the pub, marked on a pillar in the bar, with renovations in the last 10 years only the bottom marks can be seen now under the counter

probably 17 Dec 1989 and 22 Oct 1984 and batterns, more so obscuring the lower one Date, probably 02 Dec 1909 Efforts are being made to find photos of the pub interior , with this pillar, before renovations , but so far nothing found It's reported to me by 3 different people that there used to be a mark at chest high, but no one can remember the date , probably 27 Nov 1924 or 14 Nov 1931 or even 01 Jan 1877. The floor of the pub has been there since 1400s (why you have to go down steps into the main bar area) and this pillar since the Victorian era and no one can really dispute that. Someone probably redid the marks in recent times but as a public space unlikely to have moved them around without someone noticing. The 1909 mark is 0.64m above the floor and the 1984 0.74m and 1989 0.95m but which date is the topmost covered-over/erased one and its height, should be about 1.2 to 1.4m off the floor. The more general academic argument is the popular conception is that UK weather is getting more "stormy" (implied with climate change) . But inundation records as a measure of storminess does not show this, including newspaper reports back to 1770s and more scientific analysis of the tide+met and surge records , again , no obvious increase in "storminess".

I would try contacting the conservator department at the British Museum or one of the major national galleries or universities. I seem to recall that there are non-destructive techniques involving millimeter wave scanning or radiation backscatter that have been used to detect the presence of underpaintings or alterations on, say, fresco works where a transmission (X-ray) method would be impractical. Would probably work in this case but definitely not commercial off-the-shelf equipment.

Get the BBC to fund it in return for broadcast rights and free pints at the pub and you're in!

Good idea, useful publicity for the pub also. I remember seing video of some burnt ancient pipe-rolls or even older rolled up papyrus records being read at the British Library. They have some system that somehow can read individual layers of text dozens of sheets deep in such rolls, via some fancy IR laser holographic technique or something. If they tried opening the rolls they would fall into dust. I think the pubco that owns the pub would agree to steaming off the covering rather than going to that extreme, especially with TV coverage.

Den 29-12-2013, skrev N_Cook:

Sure? If I was around a location I'd seen on TV, I probably would see it, especially if it was a pub.

Leif

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beslutning at undlade det.

The "Non-Destructive Testing Instrumentation" firms make equipment that could not only do this but have better resolution than you need to read such huge letter.

Do you have a camcorder? Many of them "see" in infra-red. Try heating the area of interest, then viewing it through the camera.

Yes, if the first surface is warmer/cooler than the substrate, that's what my thermal camera would respond to. BTW, hot or cold air aren't detected, only the temperature of actual physical materials.

A test I tried when I first got the camera was to place the camera about 2 feet away from a hot (~500F) soldering iron and placing a couple of sheets of printer paper between them.. the heat of the soldering iron was no longer detectable. If I'd moved the paper close to the soldering iron, the paper would've been heated, most likely in a fairly large oval shape.

If I were to make some letters/symbols in a length of nichrome wire and covered the wire with paper or various other materials, with a small amount of power applied to the ends of the wire, the camera would detect the heat absorbed by the material and display indications/presence of the heat, but I doubt that the symbols would be clear to a random observer. As the material continued to absorb heat, there may not be any distinguishable shapes to represent the symbols.

If the covered numbers of interest were cut out of aluminum foil, or had some other attributes other than ordinary paint, the methods of detecting them would probably be much easier.

I would expect dates marked hundreds of years ago could be made by numerous means.. charcoal, carving woodburning etc. I couldn't determine if you were describing old markings that were covered over, or that the old markings were more recently marked with painted numbers and then covered.

Academics should know of historical organizations involved in recovery of lost or concealed information.. maybe not weather/climatic academics, though.

If the info were of any great significance, I would expect that someone can offer compensation to the property owner for any interruptions/restoration incurred during the recovery of the info.

-- Cheers, WB .............

So your soldering iron and paper shows unlikely. Leaves about the only possibility is trying the following. Heat up the wall evenly, then cool a flat sheet of metal with freezer spray and apply to the covering paper for some small variously timed amount of time. Hopefully cooling just the top layer and hoping the underlying black would be marginally warmer than the plaster then by secondary back heating of the paper , perhaps some resolvable script. Once we find where the black stripes are then the scripts would be located just above them

If you had a camera sensitive enough to small temperature differences, and if the lettered area absorbs heat at a enough of a faster or slower rate than the surface they are on, then you might be able to see the slightly cooler or hotter area on the surface that's on top of the letters. Why not email FLIR and ask them? Eric

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