Just finished up a project repainting my Bram Stoker's Dracula apron. The apron on this machine had some rust and crappy stickers.
First I removed the stickers and paint from the apron with citrus stripper. Then it was primed and rattle can painted. Worked well enough, still some bumpy spots where the metal was eaten by rust.
Next I scanned an original screen-printed apron using my Doxie Flip https://www.getdoxie.com/product/flip/. It is a small battery-powered scanner that is so convenient to use for small scans. I do have an HP 4670 but only use it for large areas.
The scans were brought into GIMP where I used the "Threshold..." option to reduce it to black & white.
After that the images are brought into Inkscape. The "Trace bitmap..." option is used to convert the scan to a vectorized image. Straight lines are redrawn and the paths are separated into two layers coloured for convenience.
Next the SVGs are cut in Silhouette Studio. After opening the SVG the images must be scaled 125% due to DPI differences between Inkscape and Silhouette Studio. I am using GerberMask Ultra as the paint mask with these settings:
GerberMask Ultra (resized).png
Masks are cut and then weeded under a magnifying lamp with an exacto knife and tweezers. I didn't bother trying to keep the tiny pieces like the middle of the letter A -- they are too small to manage I found. I just painted those by hand with a brush after.
Next you use transfer tape on top of the mask. I used Cricut 2002363 Vinyl Transfer Tape which is completely transparent.
Position the paint mask on the surface and tack it down on one end with painter's tape. Then peel back and cut maybe an inch of backing and adhere the mask. Remove the painters tape and slowly remove the release paper from the mask while applying it to the surface.
Push down on the stencil bits before removing the transfer tape. Still I had some problems with paint leakage under the mask due I think to the not perfectly smooth surface of the apron.
I sprayed the blue first and then the red. For positioning the red, I included the corners of the blue in the mask. I removed the corners of the release paper and aligned the stencil against the already blue paint then covered it up with scraps of paint mask. You can also include registration marks to help alignment.
I used Golden High Flow paints. They have a handy mixer app here: https://www.goldenpaints.com/mixer. I used this with a Pantone swatch book to mix up the paint. The blue wasn't that close actually so I had to adjust to get it closer.
Since I am painting on a black background I first had to lay down white. You can see on the screen printed apron this is how it was originally done too since the coloured screen inks are not opaque. I found what was best was to spray a light coat of the base black colour first to help seal up the stencil from any leaks. Then a few light coats of white before the colour went down.
Spray very light coats. If the paint goes on wet it wants to crawl under any gaps in the stencil. Very hard to resist the temptation to paint too heavy.
I did have to do a bunch of touchups with a tiny brush and black to fix some leakage under the stencil. Still, it turned out pretty well and the next one will be better. Any questions please ask.
Detail of the Dracula lettering. Color looks a bit washed out from the flash.