pertinent information, such as rework performed or disposition. The inclusion of some visible record of the indications
on a report makes the report much more complete.
Types Of Records.
The simplest record is a sketch of the part showing location and extent of the indications. On large parts it may be
sufficient to sketch only the critical area. Other types of records include preserving the actual indication on the part
(where the part is to be kept for reference), transferring the indication from the part to a record sheet or report, and
photographing the indication. These last three methods will be discussed in this section.
Preserving Indications on A Part.
Fixing Indications with Lacquer.
One of the advantages of magnetic particle inspection is that the indication is formed directly on the part at the exact
spot of the magnetic leakage field. This makes it possible to retain the part itself for record purposes, but it is necessary
to fix or preserve the indication on the part, so that the part can be handled and examined without smudging or
smearing the indication. One method of fixing the indication semi-permanently on the part is by using clear lacquer.
In order to do this the part must be dry; if the wet method has been used to develop the indication, the vehicle should be
allowed to evaporate. Normal evaporation can be accelerated by heating the part and is usually sufficient for water; it is
also possible to flow on isopropyl alcohol or other solvent that will evaporate rapidly and leave the indication dry on the
part. For an oil vehicle, use of a solvent is almost necessary to provide a dry indication in a reasonable time. It is
usually desirable to thin out the clear lacquer by adding lacquer thinner. The lacquer should either be sprayed on the
part or flowed on since brushing would smear the indication.
Applying Transparent Tape.
It is also possible to preserve an indication on a part by covering it with transparent pressure sensitive tape (such as
Scotch brand). This method is not as neat looking as the lacquer method but it is easier to apply. Before applying the
tape, the vehicle used in the wet method should be removed in the same manner as when using lacquer.
An accurate record of an indication can be obtained by lifting the particles forming the indication from the part with
transparent pressure sensitive tape (such as Scotch brand) and then placing the tape on stiff white paper. The
procedure for taking tape transfers is simple and can be accomplished quickly and accurately with a little practice. If a
report is being made and it is necessary to duplicate the indication, mount the tape transfer on a sheet of clear plastic
and use a standard duplicating process or prepare a photographic negative and contact print. When tape transfers are
taken of indications, it is customary to sketch the part and locate the position of the preserved indication on the sketch.
Dry Particle Indications.
If the indication is formed of dry powder particles, excess powder should be removed from the surface by gentle
blowing. Use a piece of tape larger than the indication and gently cover the indication with the tape. Gentle pressure
should be applied so that the adhesive will pick up the particles; do not press too hard or the indication will be flattened
too much and the tape may be difficult to remove. Carefully lift the tape from the part and press it onto the record sheet
or report. Note that tape preserved indications are usually a little broader than indications on the part because of the
flattening effect of the tape. It is easier to remove the tape if a corner of it is not pressed to the part; this leaves a tab for
Wet Particle Indications.
If the indication is formed of particles used with the wet method, it is necessary to dry the surface of the part before
applying the tape as described in paragraph 18.104.22.168.1.
Tape transfers can be taken of fluorescent particle indications, but there are some disadvantages to the process. Such
preserved indications usually must be viewed under black light to properly interpret them since the number of particles
in the suspension is much less than when using visible particles. Some transparent tape is fluorescent and the
fluorescence of the tape may mask the fluorescence of the indication.