Porous material thoroughly wetted with alcohol shows persistent wet line or area at locations of cracks or porosity. Inspection is qualitative and repeatable, but is used quantitatively with select samples to grade density variations in graphite blocks. Photography is employed to achieve permanent record of results

Hendron, J. A.

English

NASA Technical Reports Server

May 1971	 Brief 71-10103 
AEC-NASA TECH BRIEF 
Space Nuclear Systems Office 
AEC-NASA Tech Briefs announce new technology derived from the research and development program of the U.S. 
AEC or from AEC-NASA interagency efforts. They are issued to encourage commercial application. Tech Briefs are 
available on a subscription basis from the National Technical Information Service, Springfield, Virginia 22151. Requests 
for individual copies or questions relating to the Tech Brief program may be directed to the Technology Utilization 
Office, NASA, Code KT, Washington, D.C. 20546. 
Methyl Alcohol Used as Penetrant Inspection Medium for Porous Materials 
The problem: 
To provide a penetrant that can be used as an 
inspection medium on porous structural materials 
such as graphite rocket nozzle liners, nozzle skirt 
extensions, and ceramics. Such materials cannot be 
inspected for cracks and porous areas with dye 
penetrants because these penetrants leave a residue 
which can adversely affect performance in subsequent 
processing or service. 
The solution: 
A readily evaporating liquid, such as methyl 
alcohol. When a porous material with a dull surface 
is thoroughly wetted with alcohol, it will show a 
persistent wet line or area at the locations of 
cracks or porosity. 
How it's done: 
Dip the part in alcohol, or flow alcohol on the 
part's surface, and observe the surface as it dries. 
Areas without discontinuities will dry quickly, usually 
within 20 seconds. Areas with discontinuities will 
remain wet longer because they will retain more 
alcohol. Wet areas appear darker than the surround-
ing area and are readily visible for a brief period, 
during which the discontinuity can be marked. 
Graphite, unglazed ceramics, green powder-metal-
lurgy billets, and composites of chopped fiber and 
plastic that have a dull surface (as after machining) 
are all amenable to the use of methyl alcohol. It 
evaporates and leaves no residue or discoloration. 
Any other liquid that evaporates quickly can be 
used on porous materials with equal efficiency,
providing the liquid is compatible with the part 
being inspected. 
Methyl alcohol is recommended because it is 
relatively inexpensive. It is also quick, and effective. 
Though this type of inspection is usually qualita-
tive, it can be used quantitatively, with carefully 
selected samples, to grade density variations in 
graphite blocks. The surface wetting effect around 
small discontinuities results in outlining defects too 
small to be seen by unaided visual inspection. 
In addition, the inspection process may be repeated 
as often as required, and photography can be em-
ployed to achieve a permanent record of the 
test results. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
AEC-NASA Space Nuclear Systems Office 
U.S. Atomic Energy Commission 
Washington, D.C. 20545 
Reference: B71-10103 
Patent status: 
No patent action is contemplated by AEC or NASA. 
Source: John A. Hendron of

Aerojet Nuclear Systems Co.

Div. of Aerojet General Corp.

under contract to

AEC-NASA Space Nuclear Systems Office

(NUC- 10419) 
Category 04,06 
This document was prepared under the sponsorship of the Atomic
	 liability resulting from the use of the information contained in this 
Energy Commission and/or the National Aeronautics and Space document, or warrants that the use of any information, apparatus, 
Administration. Neither the United States Government nor any per-
	 method, or process disclosed in this document may not infringe pri-
son acting on behalf of the United States Government assumes any vately owned rights.
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Methyl alcohol used as penetrant inspection medium for porous materials

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