Topic: Coatings for polished aluminum?

[Bokeh]

Looking for any advice on what to treat my polished aluminum parts.  Sanding out all the scratches all over the bike and I want something that will last without being permanent like engine clear coat so I wont have to use stripper for any touch-ups or maintenance.  Does anyone have any experience with Classic Trim Coat or ShineSeal?  Both look interesting and I have read some good reviews. 

Also has anyone encountered bubbles in the aluminum?  I had some deep stains and scratches in the torque converter cover and as I sanded it I seemed to uncover little dots (pits). At first I thought maybe the sandpaper was gouging the metal as a piece of sand from the paper came off,  but now it seems as if its actually bubbles in the metal being uncovered as I sand (very tiny dots).  Anyone seen this before?

http://www.classictrimcoat.com/

http://www.shineseal.com/

Thanks!

P.S.  I would not advise anyone to sand the aluminum unless you are very familiar with sanding and slowly going through the grades of abrasives as well as knowing how to keep the surface level over the curves or you will grind flat spots in the areas of the scratches/stains you are trying to correct.  The engine I am working on was messed up originally by someone taking a wire brush to the engine covers. 

[trueblue]

I use california custom purple metal polish.  I found it took a few coats over a couple of weeks to give it protection, now it gets a coat every 6 months or so and stays pretty good in between even if I get caught in the rain.  When I did all the polishing on my bike I wet sanded it by hand, then buffed it with calico mops and wax.  Took me at least 30 hours worth of polishing.

http://www.californiacustom.com.au/california-custom-catalogue/purple-metal-polish

[Bokeh]

I know what you mean.  With the amount of scratches and deep stains from the oxidation I expect I am well over 50 hours into sanding the engine cases.  Even went down to a 150 grit on some parts.  Didn't think I would get all the deep gouges out but enough time and everything looks new again.  I have a electric die grinder with assorted pads and a Dremel with small pads for the hard to reach places.  Hope to start the polishing and buffing soon.  BTW the Dremel if you are steady enough with one works really well for the hard to reach areas around the valve cover.  They have some 320 grit wheels that work well.  You have to have a light touch and you will use quite a few as they wear down quickly.  The stainless steel and copper wire brushes for the Dremel are incredible for getting around screws (I am doing my engine fully put together) and for removing the paint around the Honda stamp on the Magneto cover.  Those brushes are soft enough they actually polish the metal and don't scratch it even though they look like they would tear the aluminum up. They also work well for getting around the SOHC stamps on the top of the valve cover. 

Thanks for the advise I will definitely look into the purple polish.  I currently have some magic blue and Turtle wax metal polish but not sure if they will leave much of a protective coat.

I hadn't tried wet sanding as I was afraid the water may start corroding the metal.  I am probably going to get to 400-800 grit then move to the polishing/buffing compounds.  Luckily the valve cover was in better shape jut have to sand a few small gouges out still and smooth the wrinkles on the back side left from the casting.  The breather cover however is gonna take a while to get perfect again.  Then I get to start on the carbs, forks and Triple trees.  This process has taken more time than anything else done to the bike so far.  If I had the money I would definitely pay someone to do it!

For anyone attempting this BUY A DUST MASK!  Aluminum Oxidation with the dust is believed to cause Alzheimers.  Look it up.  I am only hand sanding so far and on my new 3M mask the filters are near black just from this engine.  Wet sanding I am sure would cut down on the dust. I have been woodworking for over 20 years and I am very familiar with using strippers, sanding and the Dremel is the most used tool I have ever owned.  Bought one when it first came out and that one finally died on me this past year (the originals had a chuck you could use on many size drill bits, too bad the new ones don't).  Hand sanding is the best way you can get a true level surface.  You get used the feel of what you are sanding.  If you are new I urge you to work through the whole process on a spare part to get a feel for it and make some mistakes before you attempt this on your final parts.

That being said,  I am new to the buffing/polishing compounds.  Think I got it down, but wondering what a good product is to use for cleaning the leftover residue/compound between switching compounds and wheels/pads.  Saw the stuff Zephyr has but was hoping for something from the auto stores so I don't have to order anything.

[calj737]

For the "best" shine, you'll need to wetland beyond 800 grit, probably a round of 1500 then as much as 2000 to remove the most fine scratches. Polishing will then be much easier and produce a far higher luster, if that's the goal you seek.

For your Dremel, use the Green, Red, Grey ScotchBrite pads to remove oxidation and initially sanding. The speed and differing abrasions will remove more imperfections without the splatter of the aluminum. Follow with regimens of wet sanding.

[Bokeh]

For the Dremel that's what I was using for the oxidation - thery're called abrasive Buffs (Look like Scotchbrite material).  My cases have stains that go deep into the metal as well.   I also used the rubber flap wheels for a few hard to reach areas,  but wear goggles for sure with those as the rubber arms come loose and one got me right in the eye.  LOL  Yes,  I should have been wearing my safety glasses.  Looks like on Amazon they also have a purple buff but it says 320 grit as well.  The only reason I stayed away from wet sanding was I read the water starts the corrosion process.  That is why they say to use the alcohol type cleaning solutions to remove residue to keep that from happening.  When I sprayed on 409 cleaner it turned the metal a darker shade of grey instantly.  I have been debating it though.  I figured polishing cream will remove it by the end anyway or the buffing.  I also have been using some rectangular scotchbrite pads in between sanding to remove sanding lines and help the surface remain flat across the plain as well as a polishing one in between papers to see what imperfections are left.  I do have some finer grades of paper (up to 2000) to use if needed but that would have to be used wet or it would clog up immediately. I had figured the Black polishing compound would remove any scratches after the 800 grit.  But I just hadn't gotten there yet to see it.  I also use a handheld bright light while Im sanding to be able to see the surface plane as well as  looking for any imperfections across the surface.   
 
Oh and a correction - the Dremel wire brushes are Stainless and brass not copper.  Looks like they even have some plastic ones for jewelry polishing. 

Thanks,  I appreciate all the input!

[calj737]

You need to be mindful about cleansers used in aluminum, whether or not it's coated. 409 is a very alkaline product and the pH is not agreeable to alloys, hence the darkening. Water used while wet sanding is completely safe and non-destructive. You're not immersing the thing in a tank, you're simply keeping it moist to use as a lubricant.

[Bokeh]

Great thanks!

[trueblue]

I went up to 2000 grit paper, on thing I did notice when I did mine is there are imperfections that run deep into the metal, no matter how well you polish it you will always end up with tiny black spots over the surface.  I had my 'points' cover to that high a shine you could have used it as a mirror to shave.  I have since let it fade a little, I didn't like the ultra high shine look on a 35 year old bike.

[Bokeh]

Thanks!

Nice bike, I like the pinstriping, especially on the side covers.

[Harsh]

What Cal speaks is the truth.  If you want it to shine you need to wetsand then follow it up with the buffing using various compounds.  For the sealing I like the Blue Magic you mentioned.  It is what I use since it leaves behind a silicone that will help protect the metal from oxidizing.


What can be done with some wetsanding and polishing.

[Bokeh]

That's what im going for.  Nice work.

[calj737]

In your first post, you mentioned discovering small bubbles in the casting. That's not unusual. The quality of the alloys 40 years ago was not great, and with production casting methods, trapped air bubbles is all too common. This is one of the reasons why these cases won't anodize well.

Only thing you can do as you've discovered is sand them to blend them in. I wouldn't chase them too far in attempt to remove them as you'll end up removing too much metal in the surrounding area and reveal more bubbles anyway.

Make them pretty and live with the anomalies. It's a production, 40 year old piece of automotive enjoyment. Polish and ride! Obsess about other things 

[dave the welder]

don't polish. it cuts in to your ride time