Cleaning the Interior Lining and Fiberglass
The interior lining or insulation was a very high tech product in the 1970 made from a closed cell foam called ensolite laminated to a tough vinyl outer layer, it is often called Elephant Skin. Both the lining and the fiberglass cabinets are extremely durable, most standard cleaners will work without causing any harm with one exception, the acrylic windows see Care and Cleaning of Acrylic Windows. It is always best to try to clean the vinyl surface first, often any staining and discoloration can be removed leaving a clean soft white interior. The non-painted surface will be easier to clean and maintain, on badly discolored walls some people have had success using Spray 9, Simple Green or even a Magic Eraser, but if all your attempts fail you can always paint the interior. I carefully researched and tested the following method and it has stood up very well over the years.
DO NOT USE HOUSEHOLD CLEANERS ON THE FRONT & REAR WINDOWS, you will permanently damage the window surface (see section on Windows – Care & Cleaning).
Seam Tape or Caulking
The tape used on the seams of the elephant skin was actually a two sided foam tape that talcum powder was applied to the outer side, often this tape is either missing or falling off. Finding a replacement tape that will actually stick and stay stuck is difficult to find, my recommendation is to apply a paintable latex caulking to the seam gap, you can blend this to almost make the seams disappear. The product I used was DAP Dynaflex 230, which is and indoor outdoor caulking that is incredibly easy to work with and offers a 50-year satisfaction guarantee (and it cleans up with water if you make a mistake, that is until it dries). To apply I recommend making two coats, the first one fill in most of the seam, the second coat fills to final level and can be textured. First clean the area using the cleaning instructions below in the “Painting the Inside” section and allow to dry, apply the caulking sparingly using a caulking gun, forcing it into the seam gaps with a small plastic putty knife or your fingers leaving s slight depression along the seam, clean up any ridges or mistakes immediately before it sets. After the first coat sets there will probably be some shrinkage, apply a second coat with a wider plastic scraper or putty knife (use plastic as I found metal tools left dark marks on the lining), let the caulking set-up some testing areas with your finger to where the surface is skimmed over but can still be shaped. Using a damp sponge lightly press on the line to apply a texture, you will find it will look very close to the rest of the lining. After it is fully cured you can paint the entire interior, it will look like new.
Painting the Inside
After a lot of research on the interior Elephant skin lining and trying to get the surface clean and white I came to the conclusion painting was the only alternative. Researching paint I found some very interesting information. First was surface preparation, DO NOT use trisodium phosphate (TSP) as a cleaner, many paint manufacturers will VOID their warranty if it is used. The reason appears to be related to insufficient rinsing which leaves a residue that the paint will not adhere to. The recommended cleaning agent is ammonia and water in a 1:1 ratio. The ammonia water cleaner works very well on oil, grease and stubborn stains, it also does not require rinsing and dries leaving no residue (again DO NOT get this solution on the acrylic front and rear windows). After cleaning the entire interior is primed using a high adhesive primer, Zinsser Bulls Eye 1-2-3 made by Rustoleum is an excellent product and well proven by many Boler owners in this application. Over the primer use a high quality latex paint, use latex paint because the surface film allows any moisture trapped behind it to pass through the surface, moisture trapped behind oil based paints can be trapped and bubble, blisters and peeling can result. Painter’s Touch, another Rustoleum product in gloss white works extremely well.