Surface Preparation for Epoxy Bonding

Proper surface preparation before bonding with epoxies is essential. Here is a summary of prep techniques taken in a larger part from "the Bell Jar".

Aluminum and Aluminum Alloys

  1. Degrease with trichloroethylene
  2. Dip in the following solution for 10 minutes:
    3 parts sodium dichromate
    20 parts water
    10 parts 95% sulfuric acid
  3. Rinse in ambient tap water
  4. Rinse in hot (65-75 degrees C) distilled water
  5. Air dry
  6. Note: Some alloys, such as #360, only require one to three minute dip in the acid dichromate.

Copper, Brass, and other Copper Alloys

  1. Degrease with trichloroethylene
  2. Dip in either of the two following solutions
    6 parts ferric chloride
    200 parts water
    30 parts concentrated nitric acid (70%)
    25% ammonium persulfate for 1-2 minutes
  3. Rinse with distilled water and dry


Ferrous alloys other than Stainless

  1. Degrease with trichloroethylene
  2. Sandblast with 100 grit sand or etch in 15% hydrochloric acid (equal parts concentrated hydrochloric acid and water) for 10 minutes. Etched surfaces should be rinsed immediately and dried with hot air.

Freshly sandblasted or etched steel begins to rust immediately; therefore adhesive should be applied as soon as the surface has been prepared.

Stainless Steel, Chromium

  1. Degrease with trichloroethylene
  2. Etch with concentrated hydrochloric acid for 15 minutes at room temperature OR with a solution of
    90 parts water
    40 parts 96% sulfuric acid
    0.2 parts Nacconol NR (National Aniline)
    for 10 minutes at 65 degrees C followed by
    90 parts water
    15 parts 70% nitric acid
    2 parts 48% hydrofluoric acid
  3. Rinse in hot distilled water and dry with hot air.

Zinc, Lead, Nickel, and Tin

  1. Degrease
  2. Abrade(sandblast)
  3. Degrease

Stone, Ceramics, Glass

  1. Degrease
  2. Wire Brush (for stone) and sandblast
  3. Rinse with water and dry

Polar Thermoplastics (Nylon, ABS, Polycarbonate, Acrylate)

  1. Degrease with trichloroethylene
  2. Abrade
  3. Degrease

Polyethylene, Polypropylene

  1. Degrease with trichloroethylene
  2. Oxidize by immersing in a solution:
    7 parts sodium dichromate
    10 parts water
    150 parts concentrated sulfuric acid
    for 10-15 minutes
  3. Rinse with hot distilled water
  4. Dry and coat with adhesive immediately

Thermoset plastics (Epoxies, Polyurethane, Polyester, Melamine, Phenolic)

  1. Degrease with acetone, MEK, or trichloroethylene
  2. Mechanically abrade (sandblast)
  3. Degrease

Copyright 1998, Jim Lux / epoxprep.htm / 5 Mar 1998 / Back to HV Home / Back to home page / Mail to Jim