I paint Featherweights and am familiar with the prepping of a Featherweight for paint and the application of the paint. As with any paint project of importance, careful, attentive preparation of the surface to be painted is imperative if you want good results. If you are thinking of painting a Featherweight I believe a brief understanding of the paint on our machines is in order. Few really know what the paint is and not knowing can have you looking in all the wrong places. It is not japanning (small j and two "N"'s) and it isn't powder-coating, which wasn't invented until the 1980's.
This I know. The aluminum castings of our Featherweights were cleaned and prepared for paint and a special black enamel paint was applied. I refer to this as being "special" because it is a paint designed to be baked-on to the surface of the machines in an oven that is not unlike the pizza ovens of today, just bigger. This oven has a metal conveyor belt that went through a four-hundred and twenty degree "hot-box" and deposited the freshly baked enamel painted castings in a cool-down room waiting for the "transfers" (we call them decals now) to be applied.
Once the transfers were applied a top-coating of clear "four-pound cut" shellac was applied to protect the decals and impart the bright shine we all love about Featherweights.
If you paint a Featherweight you will need to remove this shellac top-coating and the removing has to be done well, throughly even. Some, especially those who have never done it before, advocate using a sandblaster to "strip" their machine's paint. Don't! You will not like the cost nor the collateral damage. I did have a machine sandblasted once so I could show students that our Featherweights really are made of aluminum, and that machine's shafts have never turned again without grinding and crunching. Paint strippers (cans of caustic goo) work, but it is a long and ugly process, and don't get any on your hands or clothes.
If you read my last blog (you should know better than to come back) I told of getting "the smell" out of a Featherweight by washing out the inside of the machine using hand dish washing soap, warm water, bottle brushes and someone else's tooth brush. Please go back to that last blog for details.
In that blog I told of wrapping the motor in plastic food-wrap and avoiding getting the exterior surfaces of the machine wet. If a little gets on the outside it is OK, but don't let soapy water just flow over the outside unchecked and you are about to find out why.
I had a machine that needed painting and it had "the smell". I normally wash a machine just before I paint it having removed the shellac and decals already, the old way. I want to get the grease and oil out of the inside of the machine and the exterior oil holes so resident grease/oil cannot compromise the new paint's application. But in the last blog I was telling of cleaning "the smell" form an assembled machine's interior, so I emphasized keeping the exterior dry while you scrubbed the inside. I literally had a machine in our kitchen sink stripped of all its external parts and the sink was protected by a layer of cardboard in the bottom with a hole cut for water drainage. I was running hot water through the machine's spool pin hole working hard to get rid of a big gob of grease I had found there in the gears up top. I turned the water heat up to hot and I appled a little extra soap. Because I would be painting this machine shortly I wasn't to worried about the exterior of the machine getting wet so I was a bit sloppy while having a good ol' time, water everywhere. (those were my wife's words, not mine) And it was at this time I noticed something. The shellac was coming off the exterior surfaces that the hot soapy water was running over. It didn't happen instantly, it was taking a minute while being bathed with the hotter soapy water running over it. The shellac could be simply rubbed off with your fingers, and that which didn't came off easily could be removed with a little steel wool.
The black baked enamel was not phased by the hot water as it removed the shellac, even from the hard to reach places. Some of you know I do not advocate removing the black baked enamel as it is a very good foundation to apply paint to, so to me this was great!
This was so exciting that I grabbed two more machines I had waiting in line to be painted and proceeded to "get water everywhere" all over, again!! This new process really works!!!
For those who are thinking "that it doesn't take much to get him excited" remember please that it normally takes five hours to remove the shellac from a machine and do it well, or eight if your machine was a 1937 model.
As explained in the last blog you must dry the machine out, and no, this does not damage the machine or render it into a pile of rust. It is just neat to have found a fast way to remove the shellac, completely, in just minutes. I had done three machines in an hour and a half and all that without creating an explosive atomosphere with acetone or the like.
This really does work! Hot water, some hand dish washing soap and maybe a little application of steel wool (two ought, 00). And oh, while you are there, wash the interior of the machine. Back to the bottle brush and not letting the wife find out who's tooth brush you are using.
Source: Dave's Blog