Touch indicating paper

I think I remember that there is a kind of "touch indicating paper".
If you are uncertain whether two surfaces touch when an assembly is
assembled, you can put some of this paper on one of the surfaces,
assemble the assembly, disassemble it, and if the touch-indicating
paper has changed colour, you know that the two surfaces did touch.
What is this kind of paper called, where can I get it, and does it
only work for metal surfaces, or does it also work for wooden
surfaces?
Michael Bell
Reply to
Michael Bell
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Marking blue is what's normally used in metalwork. It may be sub-optimal foe woodwork because it's a bit tenacious in the cleaning-off department.
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Reply to
Mark Rand
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For woodworking and similar jobs I use a suitably sized blob of blutac sometime with a little sellotape over the blob to stop it sticking to an unwanted surface. it has the advantage of also telling you the amount of clearance by measuring the thickness of the squashed blob. Would that help?
Reply to
Bob Minchin
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Don't woodworkers use a blue crayon for this purpose or did I just imagine it?
Henry
Reply to
Dragon
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Just a thought - would old fashioned 'carbon paper' used for making multiple copies in a typewriter (remember those!) do for your purposes?
AWEM
Reply to
Andrew Mawson
Yes, it helps. Thank you.
Michael Bell
Reply to
Michael Bell
Perhaps you mean Plastigauge?
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Used for test fitting plain bearings on a shaft and such.
Color of it after squishing tells you the clearance by matching it to a sample set of colors.
HTH
Reply to
pschiller42
What is wrong with the method used in the gun trade when soot from a smoky spirit lamp is used to cover one part and trial assembled. It is quick and not so messy as engineers blue.
Reply to
petercolman45
Plastigauge doesn't change colour, you measure the clearance by measuring the width of the sample after it has been compressed.
Reply to
Pete

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