OT: Ways to read hidden lettering?

some background data, for after the wallpaper glue is set over my test
patch.
The wallpaper I'm using is about 0.23mm thick and optical wavelength
opacity about 8 stops (compared with neutral density filters) , and
again in optical about 10 stops for the floppy disc material
 
webcam without IR filter and floppy disc material placed over the lens,
moved .3mm farther from the CCD for focusing. Does show the sunny
cloudless sky as darker than a nearby sunlit slate roof. Following in a
dark room. No response to a cup of boiled water . Requires 5watt into a
12 ohm vitreous resistor, >200 deg C on pyro thermometer,nothing glowing
to sight, to register an image that you can tell the orientation of the
resistor. Still waiting on IR torch, may try cone of heat and pyro
thermometer but would be nice to get a direct image rather than having
to plot pyro readings
 
IR torch arrived and I gave it a go, various power levels from a power
supply, different angles and distances and webcam filter settings but
even for the letter I deliberately put under a blank spot of wallpaper,
saw nothing convincing. Just thought of another idea, blank off around
the torch output so I can place directly on the paper and see if
penetrating IR shows anything nearby to the torch.
 
On 24/04/2015 15:45, N_Cook wrote:
Situation is wishing to read some black gloss-painted letters over white
emulsion painted plaster, but for a few decades has been covered by
wallpaper. Setting is a commercial premises that permission to
non-invasively explore would be possible but steaming off wallpaper and
remedial work (no matching new wallpaper found) is not permitted.
3 ideas so far, any suggestions relating to these , or any other ideas?
Click to expand...

I wonder if some fairly benign liquid - maybe something Freon-like -
would make the paper temporarily translucent? Probably not, but who
knows...

Cheers
--
Syd
 
On 2015-04-27, N_Cook <diverse@tcp.co.uk> wrote:
webcam without IR filter and floppy disc material placed over the lens,
moved .3mm farther from the CCD for focusing. Does show the sunny
cloudless sky as darker than a nearby sunlit slate roof. Following in a
dark room. No response to a cup of boiled water . Requires 5watt into a
12 ohm vitreous resistor, >200 deg C on pyro thermometer,nothing glowing
to sight, to register an image that you can tell the orientation of the
resistor. Still waiting on IR torch, may try cone of heat and pyro
thermometer but would be nice to get a direct image rather than having
to plot pyro readings
Click to expand...

Webcam won't respond to thermal infrared, only near infrared, like IR
LED.


--
umop apisdn
 
On 28 Apr 2015 09:24:54 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:

On 2015-04-27, N_Cook <diverse@tcp.co.uk> wrote:
webcam without IR filter and floppy disc material placed over the lens,
moved .3mm farther from the CCD for focusing. Does show the sunny
cloudless sky as darker than a nearby sunlit slate roof. Following in a
dark room. No response to a cup of boiled water . Requires 5watt into a
12 ohm vitreous resistor, >200 deg C on pyro thermometer,nothing glowing
to sight, to register an image that you can tell the orientation of the
resistor. Still waiting on IR torch, may try cone of heat and pyro
thermometer but would be nice to get a direct image rather than having
to plot pyro readings

Webcam won't respond to thermal infrared, only near infrared, like IR
LED.
Click to expand...
But the webcam may be able to see near IR reflected off of the wall
behind the wallpaper.
Eric
 
On 28/04/2015 16:38, etpm@whidbey.com wrote:
On 28 Apr 2015 09:24:54 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:

On 2015-04-27, N_Cook <diverse@tcp.co.uk> wrote:
webcam without IR filter and floppy disc material placed over the lens,
moved .3mm farther from the CCD for focusing. Does show the sunny
cloudless sky as darker than a nearby sunlit slate roof. Following in a
dark room. No response to a cup of boiled water . Requires 5watt into a
12 ohm vitreous resistor, >200 deg C on pyro thermometer,nothing glowing
to sight, to register an image that you can tell the orientation of the
resistor. Still waiting on IR torch, may try cone of heat and pyro
thermometer but would be nice to get a direct image rather than having
to plot pyro readings

Webcam won't respond to thermal infrared, only near infrared, like IR
LED.
But the webcam may be able to see near IR reflected off of the wall
behind the wallpaper.
Eric
Click to expand...

I've now tried UV shows nice bright blue flourescence of the paper but
nothing relating to the letters. Alsop tried 2 and 3 thicknesses of
floppy disc material, to use brighter near IR, but still no ghostly
apparition. Tomorrow I will try my modified "keyfob" thermal IR
thermometer with a 3W illuminator made from a resistor in a conical
metal corded lamp switch drop handle. Needs about 3W shone on the paper
only, no plaster or letters under, at 45 degrees, with pyro at 90
degrees, so give 5 to 10 degrees over ambient, its receiving cone about
15mm from the paper.
 
How bout ultrasound


And how about using theIR filtering lenses from vcr's tv's and remote controls etc. ?

How about hitting the wall with an Infreared heat lamp?
 
Will the "old trick" of very thin paper (tissue/tracing paper) and a pencil work.

You put the paper down and use a pencil, The edges generally get defined.
 
Yea, tack the paper down and take a pencil and go perpendicular to the line coloring in the detected edges. So, you want a solid large width line.

If it works, you might want to consider artist's charcoal.
 
On 29/04/2015 16:33, Ron D. wrote:
Will the "old trick" of very thin paper (tissue/tracing paper) and a pencil work.

You put the paper down and use a pencil, The edges generally get defined.
Click to expand...

So like brass-rubbing? or last message written on the notepad business.
I'll give it a go when I've finished with the other methods. I had tried
very oblique/acute ? lighting and saw nothing emerging.

My close-coupled pyro and resistor heater cone seem to be showing about
1 deg F difference between black and white areas, about 17 degrees F
above ambient. I'll have to give it a proper tryout , moving the probe
consistently in , decided on preliminary results, the cool or preheated
direction and take a grid of readings after a specific number of
seconds. My moulded up combination mount is edged with right-angle faces
so I can run it along the horizontal face of a plastic spirit level and
along the vertical wall face. The axial offset between pyro and heater
cone is a bit larger than 90 degrees because of the horizontal
separation of both. Take readings every 1/4 inch , then raise the level
1/4 inch etc.
I'll also try shining a 150W photoflood filament lamp from a fixed spot
and run the pyro around , angled so not directly in the beam and not in
its shadow either.
 
On 4/30/2015 8:17 AM, N_Cook wrote:
> 150 W photoflood just showed the irregularity of illumination

You could probably replace the wallpaper in less time than you've
already spent on this!

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net
 
On 30/04/2015 13:55, Phil Hobbs wrote:
On 4/30/2015 8:17 AM, N_Cook wrote:
150 W photoflood just showed the irregularity of illumination

You could probably replace the wallpaper in less time than you've
already spent on this!

Cheers

Phil Hobbs
Click to expand...

Ah but it feels like proper , but alternative, research.
With the pyro and heater cone sensor as it is I can reliably determine
where a 65mm broad black line is (included with my test text), a
differential of about .7 deg F over gloss black or emulsion white
painted plaster under plain bits of wallpaper and about .5 deg
differential where the paper is patterned.
I now have a good idea of improvements for mark 2.
Insulating the heater cone because the heat is heating up the mount and
transfering to the paper by conduction. So instead of running the sensor
horizontally (heater and pyro are set horizontal so I can read the LCD)
I have to make runs vertically.
Slowly moving the sensor is adequate to zero in on a 65mm wide solid
black band. So the first part of the quest is achievable, the text/s is
accompanied by a 65mm black band/s, so should be able to determine where
exactly the text or possibly texts are, as it is immediately above the
black lines.
Mark 2 would have a cutdown pyro cone , so monitoring less area of paper
and compensated with the resistor mounted in a cutdown cone and it
mounted in kiln cement rather than epoxy so I can run the heater hotter.
Also create a reference sliding face perpendicular to the wall and
vertical as well as the original just horizontal and wall contact face.
 
In sci.electronics.repair Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
You could probably replace the wallpaper in less time than you've
already spent on this!
Click to expand...

From N_Cook's previous postings, I recall that this has something to do
with suspected lettering under wallpaper in a historically listed
building - he can do all the non-destructive testing/probing he wants,
but he can't lift up the wallpaper in that building. Therefore, he has
made a hopefully similar example at home, and is refining his technique.

Matt Roberds
 
On Thu, 30 Apr 2015 20:38:32 +0100, N_Cook <diverse@tcp.co.uk> wrote as
underneath :

On 30/04/2015 13:55, Phil Hobbs wrote:
On 4/30/2015 8:17 AM, N_Cook wrote:
150 W photoflood just showed the irregularity of illumination

You could probably replace the wallpaper in less time than you've
already spent on this!

Cheers

Phil Hobbs


Ah but it feels like proper , but alternative, research.
With the pyro and heater cone sensor as it is I can reliably determine
where a 65mm broad black line is (included with my test text), a
differential of about .7 deg F over gloss black or emulsion white
painted plaster under plain bits of wallpaper and about .5 deg
differential where the paper is patterned.
I now have a good idea of improvements for mark 2.
Insulating the heater cone because the heat is heating up the mount and
transfering to the paper by conduction. So instead of running the sensor
horizontally (heater and pyro are set horizontal so I can read the LCD)
I have to make runs vertically.
Slowly moving the sensor is adequate to zero in on a 65mm wide solid
black band. So the first part of the quest is achievable, the text/s is
accompanied by a 65mm black band/s, so should be able to determine where
exactly the text or possibly texts are, as it is immediately above the
black lines.
Mark 2 would have a cutdown pyro cone , so monitoring less area of paper
and compensated with the resistor mounted in a cutdown cone and it
mounted in kiln cement rather than epoxy so I can run the heater hotter.
Also create a reference sliding face perpendicular to the wall and
vertical as well as the original just horizontal and wall contact face.
Click to expand...

NC Fraid I havnt read the whole thread! Have you tried heating a patch
of wall above ambient then and taking thermal image as the patch of wall
cools after heating source removed? Tiny differances in emissivity might
be detectable? C+
 
On 01/05/2015 06:57, Charlie+ wrote:
On Thu, 30 Apr 2015 20:38:32 +0100, N_Cook <diverse@tcp.co.uk> wrote as
underneath :

On 30/04/2015 13:55, Phil Hobbs wrote:
On 4/30/2015 8:17 AM, N_Cook wrote:
150 W photoflood just showed the irregularity of illumination

You could probably replace the wallpaper in less time than you've
already spent on this!

Cheers

Phil Hobbs


Ah but it feels like proper , but alternative, research.
With the pyro and heater cone sensor as it is I can reliably determine
where a 65mm broad black line is (included with my test text), a
differential of about .7 deg F over gloss black or emulsion white
painted plaster under plain bits of wallpaper and about .5 deg
differential where the paper is patterned.
I now have a good idea of improvements for mark 2.
Insulating the heater cone because the heat is heating up the mount and
transfering to the paper by conduction. So instead of running the sensor
horizontally (heater and pyro are set horizontal so I can read the LCD)
I have to make runs vertically.
Slowly moving the sensor is adequate to zero in on a 65mm wide solid
black band. So the first part of the quest is achievable, the text/s is
accompanied by a 65mm black band/s, so should be able to determine where
exactly the text or possibly texts are, as it is immediately above the
black lines.
Mark 2 would have a cutdown pyro cone , so monitoring less area of paper
and compensated with the resistor mounted in a cutdown cone and it
mounted in kiln cement rather than epoxy so I can run the heater hotter.
Also create a reference sliding face perpendicular to the wall and
vertical as well as the original just horizontal and wall contact face.

NC Fraid I havnt read the whole thread! Have you tried heating a patch
of wall above ambient then and taking thermal image as the patch of wall
cools after heating source removed? Tiny differances in emissivity might
be detectable? C+
Click to expand...

The trouble there is getting even heating to better than +/-0.5 deg F,
tried with a photoflood bulb and uneven to something like +/-2 deg F
 
On 01/05/2015 04:38, mroberds@att.net wrote:
In sci.electronics.repair Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
You could probably replace the wallpaper in less time than you've
already spent on this!

From N_Cook's previous postings, I recall that this has something to do
with suspected lettering under wallpaper in a historically listed
building - he can do all the non-destructive testing/probing he wants,
but he can't lift up the wallpaper in that building. Therefore, he has
made a hopefully similar example at home, and is refining his technique.

Matt Roberds
Click to expand...

Confirmed, originally 15th century but mainly 17th century, the part I'm
interested in is early 20C text on a 19C alteration
 
Efter mange tanker skrev Phil Hobbs:
On 4/30/2015 8:17 AM, N_Cook wrote:
150 W photoflood just showed the irregularity of illumination

You could probably replace the wallpaper in less time than you've already
spent on this!

Cheers

Phil Hobbs
Click to expand...

You have forgotten the context:

"Setting is a commercial premises that permission to non-invasively
explore would be possible but steaming off wallpaper and remedial work
(no matching new wallpaper found) is not permitted."

--
https://www.paradiss.dk
Ting til konen eller kĂŚresten.
Eller begge.
 
On Fri, 01 May 2015 07:47:11 +0100, N_Cook <diverse@tcp.co.uk> wrote as
underneath :

snip

NC Fraid I havnt read the whole thread! Have you tried heating a patch
of wall above ambient then and taking thermal image as the patch of wall
cools after heating source removed? Tiny differances in emissivity might
be detectable? C+


The trouble there is getting even heating to better than +/-0.5 deg F,
tried with a photoflood bulb and uneven to something like +/-2 deg F
Click to expand...

Yes I can imagine that might be a practical problem on a large area but
did you detect any test letter at all with this method? If so then a
method shoud be possible, if not then its a deadend! There is no cheap
and cheerful X-Ray method! C+
 
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