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Cleaning Painted Surfaces
Amateur Radio > E.F. Johnson Restoration
When approaching the exterior finish of a Johnson transmitter, caution must be exercised. The paint used by the factory will be damaged by some dish soaps; Dawn is one of them.
For the Johnson Viking 500 project, I planned to strip the cases for re-finishing. To show the effect more dramatically, I applied the stronger Dawn Power Wash to the cabinets to illustrate the effect.
Though these tests were made using Dawn Powerwash, regular Dawn liquid will quickly dull the finish on Johnson gear.
Here is one spray of Dawn Powerwash on the case of a Johnson 250-33 Audio Amplifier.
Rinsing after a minute, the effect is very clearly shown.
Sparaying the case again and letting it stand for about five minutes.
Another example.
Hera are two approaches to saving the original finish.
This is a photo of a Johnson Viking 500 as found. Note the finish is darkening around the VFO dial; I believe this is a result of the rubber gasket degrading over the decades. There is also a hint of rust subtly showing through the paint in many locations.
The approach involved removing the panel and carefully washing with a well-diluted mild detergent. This was followed by carefully working over the face with automotive polishing compound with a small piece of terry cloth. When polishing, be very careful to not overdo it; also, avoid the screen printed graphics as much as possible. The polishing removed the darkening around the VFO dial and removed the hints of rust found in various locations.
The final treatment was applying Meguiar's automotive paste wax and buffing with a clean terry cloth.