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Author Topic: POLISHING 101  (Read 9821 times)

Offline midnightcafe

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POLISHING 101
« on: Nov 16, 2010, 00:04:44 »
Ok, so you want shiny metal parts but don't know a thing about polishing? Check this guide out HERE. It will explain the technical details of polishing as well as cover basic buffing techniques.

Here are a few more guides you can study to familiarize yourself with the process:
http://www.dimecitycycles.com/blog/cat/tech/post/aluminumpolishing101/
http://www.poleringsguide.se/english/
http://www.slickschoppers.com/TechArticles/polishing_aluminum.html
http://www.horseapple.com/Valkyrie/Tech_Tips/Metal_Polishing/metal_polishing.html
http://www.finishing.com/109/17.shtml

If you read all of these guides, you would notice that they provide different methods and techniques. Expensive equipment can make the job easier, but if you're on a tight budget you can get the same results if you're willing to put more time and hand labor into the work. The following lists the basic necessities to begin polishing:

  • 3/4hp bench grinder with 8" wheel attachment
  • shaft extensions (standoffs) so that the buffing wheel isn't close to the motor, allowing a freer range for polishing large cases, etc.
  • buffing compound sticks: emery cake, tripoli, and white rouge
  • isopropyl alcohol or equivalent
  • Sisal buffing wheel (8")
  • Spiral Sewn wheel (8")
  • Sandpaper in the following grits: 80, 120, 180, 220, 400, 600, 1000, 1500 2000
  • #00 and #0000 steel wool
  • sanding block
  • Mother's Aluminum Polish
An electric sander (or equivalent sanding drill bits, etc) is a MUST for sanding (unless you enjoy the pain :P ) Polishing begins with sanding, and the most time will be spent at the lower grits. If the part has pitting and gouges, you will need to pull out the 80 grit, otherwise 120 is a good start. MAKE SURE that the surface has been sanded uniformly with no remaining imperfections, low or high spots. Laziness in the beginning WILL ruin a polish job, so be patient! It will be hard to determine when you are done especially for beginners, so it might be worth the time to overkill sanding at a lower grit (so long as you don't damage the part!) You should substitute a sanding tool over handwork for the low-grit, dry sanding steps when possible.

After you finish with one grit, clean and degrease the part to remove the sandpaper residue. If you are wetsanding, wash your hands. It may not seem that important, but it can affect the finish. As you transition to the next higher grit size, first look at the type of grain left behind from the previous sanding. Your goal is to completely remove that grain with the new grain of the finer grit sandpaper. One technique that proves this is when attaining a mirror finish, one should sand over the previous grain in a cross-hatch pattern to ensure the piece is completely sanded to the finer grit (works well for flat surfaces but is a difficult technique, not recommended for beginners). You will also notice that every incremental grit takes less time than the previous grit to complete. Continue this process up to 600. 1000+ can be used for those unfamiliar with using a buffing wheel.

The following method can* achieve a mirror polish (depending on the amount of time spent and experience polishing). Using your buffer, begin with emery cake on a sisal wheel. Make certain that your wheels are labeled according to the compound used, mixing compounds on a wheel is a big NO-NO! Wear gloves, goggles, and especially a mask/respirator while buffing- aluminum oxide is a carcinogen that will also blacken your snot for days. Check the polishing guide at the intro for buffing techniques. After emery, clean and degrease the part to remove the polishing compound residue. Use a new pair of gloves every time you switch compounds. Polish with tripoli on a sisal wheel. Degrease. Finish with white rouge on a spiral sewn (or softer) buffing wheel. Realize that the first two compounds are cutting compounds, and the white rouge is a coloring compound. Cutting compound smooths the surface, requiring a cutting polish motion (move the part away from spinning direction of the buffing wheel) and a cutting wheel (sisal). Coloring compound leaves a bright, shiny surface in conjunction with a softer buffing wheel (spiral sewn) and a coloring polish technique (pushing the part into the direction of the buffing wheel, using less force than you would with a cutting motion. Be careful, as it's much easier to send a part flying in a coloring motion).

Practice on a small part first, like a carburetor float bowl. Soon, you should get results like this:

BeforeAfter
Notice the grain in the reflection. This is typical, a true mirror finish would be overkill. In fact, a grainy mirror polish will more closely resemble factory polished cases on motorcycles.

The following will achieve a satin polish:
After wet sanding up to 600 grit, degrease and take out your steel wool and WD40. Start with #00 using the WD40 as cutting oil. Clean and degrease, then move up to #0000 and repeat. Clean and degrease. Keep in mind that you should be sanding in the same direction throughout to achieve a uniform grain. And for the MidnightCafe satin polish treatment, finish with #0000 and Mother's Aluminum polishing compound. Wipe away the residue buildup between applications and replace the steel wool if it gets too dirtied. Here's an example of a satin polish:

Both the fork legs and rim are satin finished.

So that's the most I can pull out of my head after spending so much time polishing some time ago. These are the methods I found worked best for me-don't hesitate to input your own suggestions regarding aluminum polishing. Cheers.
« Last Edit: Dec 28, 2010, 03:02:48 by midnightcafe »

Offline BArTY

  • Posts: 340
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Re: POLISHING 101
« Reply #1 on: Nov 16, 2010, 14:37:02 »
this is awesome! i'm saving this in my bike how to's, thanks!
My bike doesn't leak, it marks it's territory.

Offline Rocan

  • Posts: 4875
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Re: POLISHING 101
« Reply #2 on: Nov 16, 2010, 17:08:59 »
give me a week and ill post what i know about getting a true mirror polish.

agreed, anything over satin is overkill and far from factory, but i like mirrors.  :D
PJ- Cafe's don't really work right until you get rolling 70mph +

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Offline ChopperMechanic

  • Posts: 9
Re: POLISHING 101
« Reply #3 on: Dec 23, 2010, 14:03:59 »
I have spent a few hours buffing and polishing metal.  Getting used tail rotor blades off a helicopter to look like a mirror takes time.  Esp since I was polishing titanium. 

Basically you have to sand, sand, and sand some more.  Go to your local paint shop and find the highest grit sand paper you can find.  I found window polishing kits.  These are wet sand kits to polish out scratches on plexiglass windows.  The kits i use go up to 12,000 grit sand paper.  Once I have reached this point then I switch to using rouge.  You can get everything you need at Home Depot.  Comes in plastic tubes that look like big crayons.  Another trick I learned was to go buy a cheap drill with a electric cord (no cordless).  All you have to do is buy a few arbors and put whatever kind of wheels you want.  After you spend hours and more hours with the rouge, hit it up with some mothers and you are good to go.

Offline midnightcafe

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Re: POLISHING 101
« Reply #4 on: Dec 24, 2010, 18:56:38 »
just added a link to the Dime City Cycles Tech page, where they have a helpful guide on polishing.

Offline crazypj

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Re: POLISHING 101
« Reply #5 on: Dec 24, 2010, 23:57:40 »
I spent a few weeks in a polishing shop during school holidays (many,many years ago)
 You really don't need to go over 600 grit if you have an 8" buffer running at 3,000 rpm.
 Use stitched cotton wheels and black compound (emery compound) after you get everything smooth with wetordry and the lower grit papers.
 The 'professional' way to do it would be use emery powder glued to sisal wheels for roughing and cotton wheels  for fine finishing
Start with 80 grit and use brown compo to reduce cutting action, switch to 120, 240, 360/400 with compo then polish with stitched wheel and black compound, followed by loose wheel with brown compo.
 If you want a true satin finish, you have to mirror polish then run fine scotchbrite pads over surface (they make special 'polishing' wheels for it, for at least 35 yrs)
'you can take my word for it or argue until you find out I'm right'
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Offline ChopperMechanic

  • Posts: 9
Re: POLISHING 101
« Reply #6 on: Dec 27, 2010, 16:21:26 »
You are right crazypj, but I was working with titanium erosion stips on tailrotor paddles off a helicopter.  On harder metals ie: titanium, steel, stainless, etc the longer you spend sanding and the higher grit, the better the finished product will be.  I will see if i can find some pics, but used tailrotors looked like you could stick your finger right thru it when we got done.

Offline joeyputt

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Re: POLISHING 101
« Reply #7 on: Dec 28, 2010, 00:38:47 »
Sand, sand, sand, sand, by the way did I mention sand!? Hehehehe! Brother Midnightcafe this is a great thread for helping others with polishing and your parts look very nice!

One of the biggest mistakes I see do it your self polishers make is sanding in different directions. For a show quality finish you want to make sure to sand in one direction, or for a round piece like the hoops on a rim sand around the rim just as it is shaped.

I polish professionally almost daily and the single most important thing in my opinion is patience, when you have a part sanded down enough for a mirror finish you do not even need a wheel, over 90% of the polishing I do is fully sanded and polished by hand.    www.dwmsracing.com

This photo was taken in the shade and this rim was originally a heavy cast finish...


...this rim was originally a machined finish...

 
...cb550four cylinder head...
« Last Edit: Dec 28, 2010, 01:12:42 by joeyputt »
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Offline diesel450

  • Posts: 2432
  • "Fast with a past"
Re: POLISHING 101
« Reply #8 on: Dec 28, 2010, 00:54:00 »
Great thread! THe best part is that personal taste in finish is so important. There are a lot of right answers when it comes to polishing. I like it to look like pewter.

Offline midnightcafe

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Re: POLISHING 101
« Reply #9 on: Dec 28, 2010, 03:14:19 »
It's also important to know how to handle parts while using a buffing wheel. It's very easy for a part to get sucked out of your hands into the buffing motor or have it fly across your garage floor. I've had a part fly out of my hands while buffing white rouge, the final step. I picked it up to discover a deep gash in the finish and had to start all over  :'( . Stand like you are embracing a heavy wind, feet shoulder width apart, back straight. Sounds ridiculous, I know, but posture is key to preventing that part from getting sucked in and you need to be comfortable for the few hours you'll be buffing. Buffing will cause the part to heat up significantly. While buffing, try to conduct the heat evenly across the part surface so it doesn't heat up too rapidly in one spot where you might accidentally touch.


Btw so much sanding is a plus in that you'll develop Ironman hand muscles!
« Last Edit: Dec 28, 2010, 03:21:00 by midnightcafe »

Offline crazypj

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Re: POLISHING 101
« Reply #10 on: Dec 28, 2010, 03:54:53 »
You can download a free how to polish from Caswell Plating.
 As they supply some good stuff it's probably worth a look
http://www.caswellplating.com/buffs/buffman.htm
'you can take my word for it or argue until you find out I'm right'
I gave my girlfriend an orgasm the other night, but, she spat it back at me
Some people die at 25 and arenít buried until 75. óBenjamin Franklin
CB360's,  http://www.dotheton.com/forum/index.php?topic=11736.0
XS650,  http://www.dotheton.com/forum/index.php?topic=11922.0

Offline midnightcafe

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Re: POLISHING 101
« Reply #11 on: Jun 17, 2011, 19:07:33 »
I just rebuffed all my aluminum parts. A thorough twice-over is all it takes. All the haze and dirt are gone and it all looks good as new!

Offline Cafe Redneck

  • Posts: 352
Re: POLISHING 101
« Reply #12 on: Dec 31, 2011, 16:35:13 »
Thanks Midnight and DTTer's!! I just started polishing, I've added this page to my fav's so I can get to it quick for ref. I guess I found my problem, I'm just lazy and don't want to do all the sanding.

Offline aaronf

  • Posts: 6
Re: POLISHING 101
« Reply #13 on: Jan 01, 2012, 14:38:56 »
I'm definitely saving the experience shared here for later. Thanks for sharing some beautiful work, too, guys.


Offline swan

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Re: POLISHING 101
« Reply #14 on: Jan 04, 2012, 20:39:59 »
Good topic! There are no shortcuts to a mirror finish.
I would add the importance of a good light source to ensure you have sanded out the scratches from the previous grit.
1966 Triton cafe, 1962 BSA Gold Star DBD34, 75 CB400F cafe and CB750 project.
BSA Gold Star barn find restoration
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