TDR Project. Aluminium Polishing (Take 2)

My first attempt at aluminium polishing was pretty good but there were still small (but still visible) horizontal scratches in the finished item.  My first thoughts were that this was a “grain” in the sheet aluminium used to make the exhaust end can.  With this in mind, I decided to try the process again but this time start with the coarsest sanding grade at right angles (vertically or up and down) to the aluminium “grain”.

Result After Sanding Horizontally With 40 Grade

In the close-up photo (below) you see the vertical or up and down direction of the first sanding grade.

Grade 40 Sanding Close Up

I then proceeded to sand using the 120, 240 and 360 grades in alternating horizontal/vertical directions.  Each time I changed down a grade I ensured that I removed all traces of the previous grade’s sanding marks.  The photo (below) shows the 40 grade (vertical) sanding on the lower half of the piece and the 120 grade sanding (horizontally) on the upper half.

120 Grade Sanding (Top Half Of Piece). Click To View Large, Close Up Image.

The final sanding grade (320) finish can be seen in the photo below (sanded horizontally):

320 Grade Sanding Finish

I then moved to the white/blue polishing compound and the stitched mop and finished off with the felt mop and the green polishing compound.  The polishing was completed with some metal poilsh and a cloth to remove the black aluminium residue.  I was rather dissapointed to find that the exhaust still had some scratch marks in the final finish, however they were not as visible as the ones found after my first attempt.

Second Attempt Result

I then remembered that I had gone from the 320 grade sanding straight to the stitched mop and white/blue compound.  I had not used the coarser “string” mop and the grey polishing compound.  To correct this I then used the “string” mop and grey compound in the opposite direction to the small scratches and then repeated the polishing steps with the sticthed mop and felt mop (in the opposite direction to the “string” mop).

This worked!  After giving it a final rub down with the metal polish there it was: a beautiful mirror polished finish without the grainy/scratched appearance!

Finally Success 3rd. Time Lucky

Close Up The Final Successful Process

The method clearly requires you to change between every grade of sanding/polishing.  Don’t be tempted to skip any, there are no clear shortcuts (I think).

I’ve only done this for one small strip of the exhaust can, so there’s still some work to do to complete both end cans and the swingarm…..  The process requires patience but if you are in the right state of mind it can be very relaxing, therapeutic and rewarding.