(1) One-part materials. This type of material is compounded by the manufacturer and ready for application as
packaged. However, the consistency of some materials may be altered for the purpose of satisfying a particular method
of application, when so stated herein or in the manufacturer's instruction. When thinning is desired, the proper thinner
must be used
(2) Two-part materials. This type of material requires separate packaging in order to prevent cure prior to
application. These parts are identified as base compound and accelerator.
(a) Add accelerator. Prepare material for use by mixing required amount of accelerator with base
(b) Mix immediately. Immediately after adding accelerator, thoroughly mix by stirring or folding, depending
on consistency of material. Apply immediately to prevent curing prior to application.
(3) Formula for mixing. Instructions for mixing should be furnished with glue. Glue will be in two containers, one
of which will contain resin proper in liquid form, the other the catalyst in either liquid or powder form. In the absence of
manufacturer's instructions for mixing factory weighed portions of glue, do not use glue. The effect of the amount of
catalyst on the joint is too critical to attempt to establish proper proportions by trial batches. When glue does not mix to
consistency suitable for spreading, it should be discarded. Normally, no water or other solvent should be added.
(4) Procedure. Mix entire amount (1/2 pint) with weighed amount of catalyst (hardener) furnished in the capsule.
Avoid air entrapment and incomplete mixing. Add no material in an effort to thin glue after original mixing. Discard
when not suitable for spreading.
Curing. Cements and sealants are cured by chemical reaction (accelerator) or solvent evaporation. The cure
can be hastened by use of heat or warm filtered air, not to exceed 110 °F (43.3°C), applied gradually increase the
temperature as the material begins to set until the maximum 110 °F (43.3°C) is reached. Hold at this temperature until
the material becomes tack-free and chip-free.
6-2. Adhesives and Cements. Cement types and uses are explained in the following paragraphs.
Cement Types. There are two distinctive types of cement, the solvent release type and the vulcanizing type.
(1) Solvent release. The general characteristics of solvent release cements are described in the following
(a) Bond strength. Solvent release, or air drying, does not cure. The bond which is formed is due to the
strength of the materials after the solvent has evaporated and left the cement dried to the object.
(b) Tacky-dry test. The term tacky-dry is used in the majority of application instructions. This should be
interpreted as allowing the solvent to evaporate to the point where there is slight adherence to the film of the cement. To
determine the state of tacky-dry, press a knuckle on the film. There should be a slight adherence to the knuckle, but the
film should not stick.
(c) Variable drying time. Drying time cannot be definitely stated because the time element depends upon
characteristics of the cement, the thickness of the coat, method of application, and number of coats.
(d) Full adhesion. After cement has been applied and becomes tacky-dry, press surfaces firmly together
and roll down. The cement does not reach its full adhesive and cohesive strength until the solvent has escaped.
(2) Vulcanizing. Characteristics of vulcanizing cements are described in the following paragraphs.
(a) Action. Vulcanizing is a process which brings about the bonding of structural elastomers in this process,
a chemical action takes place on the mating surfaces of the elastomers.
Acrylic monomer and polymer base adhesive MIL-A-8576 contains a volatile liquid which
may prove toxic if vapor is inhaled over extended periods. Use only with adequate
ventilation. When accidentally spilled on hands or skin, remove immediately by
dissolving with ethyl alcohol, Federal Specifications O-E-760, followed by washing with
soap and water. Over-exposure symptoms are drowsiness, dizziness, and nausea.
Treat by wrapping patient in blankets, provide plenty of fresh air, and obtain medical