How to Paint a Steel Hull With Coal Tar Epoxy

Coal tar epoxies are epoxies that contain coal tar pitch, as an added defense against rust on steel surfaces. Used as a hull interior paint on steel and aluminum hull vessels during construction, coal tar epoxy is also used as a bottom paint, either by itself, or as the precursor to applying an anti-fouling bottom paint. Like all epoxies, coal tar epoxy is a two-part paint, consisting of a resin and a hardener. The two parts must be mixed thoroughly before the paint can be applied.

Things You'll Need

• Heavy-lift dry dock
• Commercial sandblasting equipment
• Marine surface sealer
• Commercial spray painting equipment
• Coal tar epoxy paint
• Commercial paint mixer
• Paint brushes
• Paint rollers

Instructions

1. Bring the vessel into a heavy-lift dry dock. This allows all areas of the exterior of the hull to be properly cleaned and painted.

2. Sandblast the hull with commercial sandblasting equipment to remove all preexisting paint and any marine growth. Any paint or marine growth remaining on the hull will cause the coal tar epoxy paint to fail to adhere correctly.

3. Seal the hull surface by applying a marine surface sealer to the hull with commercial paint spraying equipment. Sealing the surface prevents the coal tar epoxy from bleeding into anti-fouling coatings applied on top of the coal tar epoxy by preventing the interaction between the steel and the coal tar epoxy that causes the epoxy to bleed into the anti-fouling paint.

4. Mix the resin--which contains the coal tar pitch--and the hardener in small batches while the hull is being sealed using a commercial paint mixer. Small batches are appropriate because the coal tar epoxy, unlike many paints, is too thick to apply with spray equipment.

5. Apply the coal tar epoxy to the bottom with brushes or a roller. The coating should be as thick as directed in the work order for the bottom painting, to avoid cost overruns from using excessive paint.

Tips & Warnings

• Full body protection is recommended, including fully-contained breathing systems, when working with coal tar epoxy.

References

• "Corrosion Prevention by Protective Coatings "; Charles G. Munger, Louis D. Vincent; National Association of Corrosion Engineers, 1999

Resources

• Read this Article in Spanish
• "Marine Painting Manual"; A. M. Berendsen, et al.; Springer, 1989; p. 127 ff