a grinder attachment wire brush will remove all surface material and the actual aluminium of the cover if left / pressed too hard and will leave score marks which then require sanding out or filling (then sanding). better to use a paint removal pad such as this:
http://www.ebay.co.uk/itm/2-x-Paint-Rust-Grinder-Remover-Wheel-Disc-For-115mm-X-22-2mm-Angle-Grinders-/381337258554?hash=item58c978ca3alikewise blasting can leave a pock marked finish if done with a harsh medium or performed without care. after blasting the inside of the cover will require meticulous cleaning to ensure all media is removed.
chemical dipping is the preferred method of paint removal as it leaves the aluminium intact. this can be replicated at home with wire wool and parafin (or similar) but is painstakingly slow.
rather than any of these a bucket of water and some wet'n'dry will produce good results. 400 grit for starters should be fine unless corrosion is really bad, keep it soaking wet and rub away until the entire outside surface is smooth. complete paint removal is not necessary. 400 will also leave scratch marks, ideal for primer adhesion. dry the piece thoroughly, wipe with pre-paint / panel wipe, dry again and wipe with a fresh tack cloth before spraying with primer. i would recommend the pro-xl range:
http://www.ebay.co.uk/itm/Pro-XL-Super-High-Build-Primer-500-ml-Aerosol-GREY-/111781431426?hash=item1a06b14882two coats of this will give sufficient depth of paint to allow sanding back without sanding through. allow at least 30 minutes to dry but ideally 24 hours then hit it with 800 or 1000 grit (gently - let the paper to the work always) until happy with the result and then repeat the prep process before praying at least two top coats of simoniz:
http://www.ebay.co.uk/itm/SIMONIZ-MOTORCYCLE-PAINT-SILVER-ALUMINIUM-ENGINE-CASE-PAINT-HIGH-TEMPERATURE-/350503578045?hash=item519ba429bdwith care and attention to detail a factory quality finish is achievable. for a piece like this i would tend to stand it on two aerosol lids on the inside of the underside so that no edges are flat to a surface. i would also mask all holes and the underside carefully. your chosen environment will affect dust/hair levels greatly - consider vacuuming the shed/garage and settling dust with a sprinkling of water on the floor where paint will be applied, particularly the colour coats. hanging the piece so that the main surface is vertical also helps with this but makes spraying more difficult. temperature affacts results, 21 degrees is ideal, more is fine but less can lead to cloudly finishes and poor adhesion. don't lay down too much paint in any one session, build layers carefully. and finally - wear the best mask that your can find / afford!
if you want me to paint it i can. hth.
