TM 1-1520-240-BD NOTE High temperatures and humidity shorten   pot   life   of   adhesives,   low temperatures will lengthen it. (2) No addition or omission of ingredients, or deviation     from     mixing     or     blending     procedures     is permitted. (3) Thinning   of   adhesives   is   not   permitted unless specifically allowed in the procedure. (4) All multiple-part adhesives must be blended by weight, within 2-1/2 percent. (5) All multiple-part adhesives must be blended  in  dean,  metal,  glass,  polyethylene,  or  Teflon containers only. c. Preparation    of    Bonding    Surfaces.        Unless otherwise specified, all bonding surfaces except thermoplastic, phenolic, and melamine, must be thoroughly  cleaned  using  dean  cloths  moistened  with methyl-ethyl-ketone.          Thermoplastic,     phenolic,     and melamine  must  be  lightly  sanded  to  remove  the  glass and then cleaned with aliphatic naphtha. d. Application of Adhesive System No. 1. WARNING The adhesives under this system are toxic  and  flammable.    Work  in  well- ventilated areas away from flame. (1) (Refer    to    Table    2-5    for    the    list    of acceptable adhesives.) Clean the faying surfaces using methyl-ethyl-ketone. (2) Thoroughly     stir     adhesive     in     its     own container using a spatula. NOTE If    adhesive    is    to    be    applied    by spraying,    it    may    be    thinned    with methyl-ethyl-ketone. (3) Brush  or  spray  one  coat  of  the  adhesive on each faying surface. NOTE On  porous  surfaces  such  as  textiles and     wood,     two     coats     must     be applied.  The first coat must seal the surface and be completely dry before application of the second coat. (4) Allow adhesive to dry until tacky, then join surfaces.      Apply   sufficient   pressure   to   ensure   solid contact. e. Application of Adhesive System No.  3. WARNING The adhesives under this system are toxic.   Work   only   in   well-ventilated areas. NOTE The    pot    life    is    40    minutes    for adhesive  (item  39,  Table  2-5)  and  45 minutes  for  adhesive  (item  40,  Table 2-5). (1) (Refer  to  Table  2-5  for  list  of  acceptable adhesives.) Clean faying surfaces using naphtha. (2) Stir   individual   components   in   their   own container then blend them as follows: (a) If  adhesive  (item  39,  Table  2-5)  is being used, blend 100 parts, by weight, of part A with 34 parts, by weight, of part B. (b) If  adhesive  (item  40,  Table  2-5)  is being used, blend 100 parts, by weight, of part A with 40 parts, by weight, of part B. (3) Apply a coat of primer J (item 116, Table 2-5)   to   all   surfaces   except   brass   or   neoprene.      Use primer  H  (item  115,  Table  2-5)  for  brass  or  neoprene surfaces. Allow primer to dry for 30 to 40 minutes. NOTE Primer is not required on polycarbonate plastic surfaces. (4) Apply the adhesive to both faying surfaces using a brush or a spatula. (5) Join    coated    surfaces    and    apply    light pressure. (6) Allow   adhesive   (item   39,   Table   2-5)   to cure  for  3  days  at  70°F  (21  °C).    Adhesive  (item  40, Table 2-5) cures in 2 days at same temperature. 2-50