(c)
Exchange soiled cloths for clean ones frequently. Use clean cotton or rubber gloves.
(d)
Wipe off solvent, Series 88 (Ref AMM/SOPM 20-30-88) with a clean, dry cloth while the surface is still wet.
(e)
Repeat above operations until cleaning cloths show no soil. This procedure shall be performed no more than 1 hour prior to the application of the adhesive.
(3)
Cleaning of Unprimed Clad Aluminum
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May 01/98 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 51-51-11 Page 803
(a) Pre-cleaning 1) Remove any loose soil, excess grease or oil by wiping with a clean cloth. Care should be taken not to smear soils over any larger surface than necessary.
2) Solvent clean the surface by wiping with a cloth dampened with solvent, Series 88 (Ref AMM/SOPM 20-30-88). Wipe off solvent with a clean, dry cloth while the surface is still wet.
3) The following abrading requirement may be omitted when Pro Seal 890 material is used and the aluminum shows no sign of grease, wax, or oily substance after the above pre-cleaning operation. The clad aluminum faying surface shall be lightly abraded with Scotchbrite aluminum oxide material until the bright clad faying surface is uniformly dulled. Do not use soiled or ragged Scotchbrite material. Remove the dust by wiping with clean cloth.
(b) Hand Cleaning 1) Apply solvent, Series 88 (Ref AMM/SOPM 20-30-88) to surface by dispensing from squirt or squeeze type bottles. Do not dip the cloth in the solvent container. 2) Rub the surface with gauze or cheesecloth until the major portion of soil is removed. Scrub with a soft bristle brush if necessary to remove difficult soils. 3) Exchange soiled cloths for clean ones frequently. Use clean cotton or rubber
gloves. 4) Wipe off solvent with a clean dry cloth while the surface is still wet. 5) Repeat above operations until cleaning cloths show no soil. This procedure shall
be performed no more than 1 hour prior to the application of the adhesive.
(4)
Cleaning of BMS 10-11 Primed Metal
(a) BMS 10-11 primed metal need not be cleaned if it is to be bonded within one to six hours after primer application. Primed metal 6 to 48 hours old shall be cleaned per paragraph (3)(b) except that naphtha or toluene shall be used. Primed parts over 4 hours old shall be cleaned per paragraph (3) (b).
(5)
The cleaned faying surfaces shall not be touched with bare hands at any time up to and including assembly for bonding. It is essential that the bond areas are not contaminated in any manner.
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C. Preparation and Application of Adhesive
(1)
The base component shall be mixed thoroughly with the manufacturer's recommended amount of matched curing component (marked with the batch number of base component with which it is to be used) so that the mixture is homogeneous. Care must be taken to minimize entrapment of air in the sealant during mixing.
(2)
The material shall not be applied when the temperature of the structure is below 50°F.
(3)
Apply a thin uniform coating of 50 (+ 10) grams per square foot of mixed material to each faying surface. A serrated edge spreader such as that shown in figure 801 is recommended for spreading the adhesive on large faying surfaces. For spreading a relatively high viscosity batch of the adhesive, a spreader with finer serrations is recommended. Spread adhesive must have sufficient thickness to produce adhesive flash around the edges of the rub pads when the curing pressure is applied.
(4)
The parts shall be assembled within the time specified in figure 802.
(a)
Lay the coated rub pads down carefully so that the edges are aligned with the panel edge and with one another, not overlapping. When the pads are laid in place, smooth the surface with a roll of gauze or cheesecloth or with a clean roller in order to squeeze out all entrapped air. Avoid using excess smoothing pressure, which would squeeze adhesive out on the bond line, resulting in an adhesive starved joint.
(b)
Excess adhesive may be removed by wiping with a clean gauze moistened slightly with methyl ethyl ketone. Take care not to allow methyl ethyl ketone to seep into the bond line. If methyl ethyl ketone is used, allow 10 minutes drying time to evaporate any residual methyl ethyl ketone before applying curing pressure.
(5)
Curing pressure shall be uniformly applied to the part within the time specified in figure
802.
(a)
All holding devices shall exert a reasonably uniform pressure to the bonded area sufficient to extrude a continuous adhesive flash at the bond line.
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