Thunderchief
Devout Dirtbag
claret73":3aytm2z0 said:
Yeah no problem, nothing special just a lot of careful hard work! ;-) however I should say that painting them may not be all that durable.
Preparation
I started by using a quite coarse dremmel grinding wheel, on the black anodised section, to remove the anodising and level off the scratches as much as possible.
I then swapped to a much softer dremmel grinding wheel, unfortunately I don't know the name of it, but it is very soft gray material that wears out very quickly. It is perfect for quickly smoothing out the scratches on both the black section and the polished section.
You need to bear in mind that the only way to remove scratches without filling is to remove enough of the surrounding martial to flatten it out. So if you have deep scratches on the polished section which you may not be able to remove them completely without compromising the thin alloy. I was lucky and was able to grind away enough to remove all the scratches.
Once you have removed the scratches with the soft grinding wheel, you can them move on to wet sanding, use a coarse grade at first to remove the grinding marks, something like 800 grit or 400 if you have been a bit too heavy handed with the grinding wheel. ;-)
Polishing
When the grinding marks are removed, you can move on to polishing the alloy on the section that is not painted. I used a wet sand with 1500 grit to get close, and then swapped to 2500 grit to get a good dull finish. Finally I used a metal polish and a soft cotton buffing wheel on a power drill to achieve the high shine. You can use autosol and a lot (A LOT) of elbow grease if you don’t have a polishing wheel
Now the polished alloy section is done you can move on to the painted section (you could re anodised if you don’t have to fill)
Paint Preparation
Clean the alloy with a solvent to remove lose particles and any grease/polishing compound, that may have gotten on to the section to be painted. If you’re painting with cellulose paint, use cellulose thinner.
You will need to fill the deep scratches with strong filler; I used quick set automotive body filler that comes in a tube, very handy for small jobs.
Apply the filler, sparingly, otherwise you will be sanding forever! ;-)
Once the filler is set, you can sand away the excess. Use wet sanding again, rinsing the paper often, to help prevent build up of filler on the paper. You should sand until only the bare minimum of filler is left.
You may find that one application is not enough, repeat until the deep scratches/dents are totally filled.
Painting
Mask the polished section off, taking care to make a nice edge where the paint will meet the polished alloy. Use primer filler spray paint, and coat the section to be painted. Once set, wet sand the primer down, you are filling the very small imperfections now so use a fine 1500 grit paper. You may find that this first sanding remover almost all the primer, this is ok. You will have to repeat this process until you get a perfectly smooth finish. Colour coat will not fill any imperfections, so you must get it smooth now.
Once smooth, apply your colour coat. To get a good gloss finish you need to do this in the warm, either inside, or on a hot day if outside. Apply a light mist coat first and then apply a thicker coat just before the mist coat is totally dry. Wait again for this coat to be nearly dry (with cellulose this may only be a matter of minutes) and apply a final top coat.
Allow this to harden for at least 24 hours, preferably longer, unless you have a paint oven to bake it in! ;-)
Hopefully you should now have a perfect gloss finish! ;-) Unfortunately there is a good chance you don't, don't panic you can rescue it sometimes.
If you have a dull finish or perhaps a paint run or other imperfections you can wet flat the paint before applying lacquer. Using 2500 grit paper or finer if you can get it, sand the paper in straight motions, try to avoid using circular sanding. Sand, washing the paper often, until you get an even, dull finish. You may have to recoat if you have had too sand too much. Hopefully though a light sand will be enough.
Now you can apply lacquer over the colour coat, if you have had to flat the paint down, don't worry about the finish being dull, the lacquer will fix that. As with the colour coat, heat is your friend. A nice hot day or inside is best. Apply the lacquer in a heavy coat, this can be quite tricky to do without runs, but is essential for a high gloss finish. You can try to rotate the part to prevent runs.
Hopefully now you have a good finish, allow the lacquer to harden for 24 hours and then you can carefully remove the masking.
Hope that helps?
Cheers.
Simon.
