- Thread starter Mr shiney
- Start date
Steve Langs Bible on polishing it dont get better than this.contained in this thread::http://www.mig-welding.co.uk/forum/threads/polishing-stainless.49627/
or copied below, Thanks go to Steve for this in depth article
POLISHING
What is polishing all about really ???
Polishing is the process of removing surface imperfections so that it reflects light rather than absorbs it. The more light it reflects the better it is polished.
When a piece is polished, what we do is to change its surface. We remove surface imperfections by scratching them off with various grits.
We start with a coarse grit and gradually reduce it to finer grits. Each grit has a scratch factor. We work our way from a coarse scratch to one that cannot be seen by the eye. The small particles on the surface become polarized. They line up like soldiers and the surface becomes slightly harder, and more resistant to oxidization, acid and water stains. Water runs off easier, as it is can’t get a grip on the polished surface. It is also more resistant to corrosion, just because of its smoothness and its hardness. Of course it will dull with time due to handling and chemicals in the atmosphere.
Corrosion sets in when the ions no longer line up like soldiers. The surface gets attacked by chemicals in the air and the little soldiers start falling by the wayside one by one.
Once the oxidization starts, if left unattended the polished surface dulls and can discolour.
Safety
Polishing machines are dangerous in themselves so be careful of loose clothing etc etc.
Wear a decent quality face mask as the dust you will making is not good to breathe, also wear overalls as polishing is a real dirty process.
Machines
Polishing machines come on a variety of forms, some have a pigtail out of each side while some only have a pigtail on one side (these usually have a grinding wheel on the other end)
All the best machines are 3 phase 3/4HP basically as the 3 phase gives more grunt to the machine, obviously most home workshops do not have a 3 phase supply but these days Digital phase converters give the home polisher a far better range of machines they can buy.
The single phase machines are still a good choice as is a 3 phase machine converted to single phase but neither will have the grunt of the 3 phase; this means polishing will just take a little longer.
If your looking for a 3 phase machine to convert to single phase you will need a machine that has the motor mounted in the base and is driven by a belt, the top mounted motor type cannot be converted as the motor shaft is the actual polishing spindle.
There are also bench grinders that can have polishing mops mounted to them for very light work, these are not ideal as the motors are generally low horse power.
Maximum Thickness of Polishing Wheels
Motor Size
Wheel Diameter
4”
6”
8”
10”
12”
1/6 hp
1”
5”
-
-
-
1/4 hp
1.5”
1”
5”
-
-
1/3 hp
2.5”
2”
1”
-
-
1/2 hp
3”
2.5”
2”
1”
-
3/4 hp
4.5”
3.5”
2.5”
2”
1”
2 hp
4.5”
4.5”
4.5”
3”
1.5”
Mop running speeds
For best results your wheel should maintain a surface speed of between 3600 & 7500 Surface Feet Per Minute. (SFPM). The higher your speed, the better and quicker your results.
Formula for calculating surface speed of wheel in SFPM.
SFPM = 1/4 x diameter of Wheel x RPM (revs of spindle per min.)
DETERMINING GRIT SIZES and BUFFING COMPOUNDS
The question often asked is, 'Which grit should I use first?” Unfortunately, there is no cut and dried answer to this, because it really depends on the condition of the part. So, let’s discuss some examples:
1) Aluminum Cover with one deep scratch.
To successfully remove the scratch, ALL of the material around the scratch has to be disposed of. In our example, this means a lot of aluminium! Initially, we are concerned with getting as much aluminium sanded off as quickly as possible, so we would use the coarsest abrasive available, say a40 grit sandpaperon a flat block. It would be of NO USE to try to buff out this deep scratch with a buffing wheel, because the wheel would remove more material from the hole, as well as the surrounding areas. By keeping the abrasive on a flat block, no further material can be removed from the hole.
As the scratch is lessened, the grit size of paper is reduced from40, to 80, 120, 240, 320 and finally 600. Once the surrounding material is removed, then the actual polishing can be started.
Buffing compounds will be determined by the size of the scratches. If you have used a 600 grit paper, you may like to proceed directly to awhite buffing compound. If fine scratches are visible, then you'll need to 'back off' and go to theGrey compoundbefore retrying the white.
2. Aluminum Side Cover - just dull.
Obviously, it would be a step backwards to start treating this piece by using the technique in our first example. As there is no large metal content to be removed, you could virtually dispense with the sandpapers and move directly to the polishing aspect of the part. TheBrown buffing compoundwith aSisal wheelcould be employed to see if the shine is good enough. If not, then use agrey compound, and then rework the part using the brown compound.
3. Aluminum Wheel Casting.
Many wheels are prepainted, directly over a rough sand casting. Remove the paint usingNitromors, to expose the aluminium. The 'pimples' caused by the sand cast have to be removed to flatten the metal ready for polishing. Because of the difficult contours of the wheel, it is virtually impossible to sand with a flat block, so this is whereGreaseless Compoundcomes in. Start off with the 80 grit, using aspiral sewn wheelor, for the awkward areas, a felt bob. Then proceed through the various grit sizes of Greaseless, until the metal is smooth , all 'pimples' are removed and an even 'flat' finish is achieved. The polishing should only begin once all traces of 'pimples' are gone. UseGrey Compoundfor most of the polishing work, and finally, on a fresh or cleaned wheel, buff lightly with theBrown compound.
Initial rough cutting
Professional polishers do their roughing out on a belt on the end of a 3 phase machine, obviously the home workshop isn’t going to have this feature but there are large diameter flap wheels to mount to a pigtail available in grits from 40g to 400g
Also mops can be turned into good cutting mops by the addition of Red Head Wheel cement & aluminium oxide grit, the mop is liberally coated in the water based glue and then the mop is rolled through the oxide so that the surface is coated this is then left to dry. The oxide grit is available in grits from 40g to 320g
Another useful wheel is the felt mop which can also be glued with aluminium oxide the same way.
Often to tone down the cut of the wheels a Grease compound is used on the wheel, this reduces the finish cut even more.
Polishing Mops
Where polishing mops are concerned the world is your oyster, there are many types of mops available for specific jobs, the ones that interest us mostly are Sisal, Cotton Stitched or White Close Stitch Mops & Loose Finishing Mops. Mops are available in several diameters from 5” to 12” and usual widths are 1” or 2”
Mops need to be cleaned out regularly with a rake, a rake is a double handled piece of wood with spikes on one side that is pressed against the revolving mop, a piece of wood with nails banged through it does an inexpensive and excellent job.
THE SISAL BUFFING WHEEL
Sisal is a slender, hard, cellular strand of fiber that has demonstrated its great strength and tough resiliency in the form of binder twine, cord & rope for many years. These qualities, along with its natural abrading and grease absorbing characteristics, provide an ideal buffing wheel fabric.
Sisal buffing wheels will provide both polishing and cutting action. They will remove stretcher strains, orange peel, polishing wheel grit lines, light die marks, etc. To effect a fast cut, use a sisal wheel
Polishing Compounds/Soaps
There are many manufacturers of soaps but Canning & Menzerna are about the best, Soaps are rated by the cut & gloss they give, some have a aggressive cut but low gloss while others have very little cut but have a high gloss.
A quick word about colour coding of soaps is needed as not all manufacturers use the same, It’s always best to ask your supplier which soap will give you the results you seek.
Continued:
or copied below, Thanks go to Steve for this in depth article
POLISHING
What is polishing all about really ???
Polishing is the process of removing surface imperfections so that it reflects light rather than absorbs it. The more light it reflects the better it is polished.
When a piece is polished, what we do is to change its surface. We remove surface imperfections by scratching them off with various grits.
We start with a coarse grit and gradually reduce it to finer grits. Each grit has a scratch factor. We work our way from a coarse scratch to one that cannot be seen by the eye. The small particles on the surface become polarized. They line up like soldiers and the surface becomes slightly harder, and more resistant to oxidization, acid and water stains. Water runs off easier, as it is can’t get a grip on the polished surface. It is also more resistant to corrosion, just because of its smoothness and its hardness. Of course it will dull with time due to handling and chemicals in the atmosphere.
Corrosion sets in when the ions no longer line up like soldiers. The surface gets attacked by chemicals in the air and the little soldiers start falling by the wayside one by one.
Once the oxidization starts, if left unattended the polished surface dulls and can discolour.
Safety
Polishing machines are dangerous in themselves so be careful of loose clothing etc etc.
Wear a decent quality face mask as the dust you will making is not good to breathe, also wear overalls as polishing is a real dirty process.
Machines
Polishing machines come on a variety of forms, some have a pigtail out of each side while some only have a pigtail on one side (these usually have a grinding wheel on the other end)
All the best machines are 3 phase 3/4HP basically as the 3 phase gives more grunt to the machine, obviously most home workshops do not have a 3 phase supply but these days Digital phase converters give the home polisher a far better range of machines they can buy.
The single phase machines are still a good choice as is a 3 phase machine converted to single phase but neither will have the grunt of the 3 phase; this means polishing will just take a little longer.
If your looking for a 3 phase machine to convert to single phase you will need a machine that has the motor mounted in the base and is driven by a belt, the top mounted motor type cannot be converted as the motor shaft is the actual polishing spindle.
There are also bench grinders that can have polishing mops mounted to them for very light work, these are not ideal as the motors are generally low horse power.
Maximum Thickness of Polishing Wheels
Motor Size
Wheel Diameter
4”
6”
8”
10”
12”
1/6 hp
1”
5”
-
-
-
1/4 hp
1.5”
1”
5”
-
-
1/3 hp
2.5”
2”
1”
-
-
1/2 hp
3”
2.5”
2”
1”
-
3/4 hp
4.5”
3.5”
2.5”
2”
1”
2 hp
4.5”
4.5”
4.5”
3”
1.5”
Mop running speeds
For best results your wheel should maintain a surface speed of between 3600 & 7500 Surface Feet Per Minute. (SFPM). The higher your speed, the better and quicker your results.
Formula for calculating surface speed of wheel in SFPM.
SFPM = 1/4 x diameter of Wheel x RPM (revs of spindle per min.)
DETERMINING GRIT SIZES and BUFFING COMPOUNDS
The question often asked is, 'Which grit should I use first?” Unfortunately, there is no cut and dried answer to this, because it really depends on the condition of the part. So, let’s discuss some examples:
1) Aluminum Cover with one deep scratch.
To successfully remove the scratch, ALL of the material around the scratch has to be disposed of. In our example, this means a lot of aluminium! Initially, we are concerned with getting as much aluminium sanded off as quickly as possible, so we would use the coarsest abrasive available, say a40 grit sandpaperon a flat block. It would be of NO USE to try to buff out this deep scratch with a buffing wheel, because the wheel would remove more material from the hole, as well as the surrounding areas. By keeping the abrasive on a flat block, no further material can be removed from the hole.
As the scratch is lessened, the grit size of paper is reduced from40, to 80, 120, 240, 320 and finally 600. Once the surrounding material is removed, then the actual polishing can be started.
Buffing compounds will be determined by the size of the scratches. If you have used a 600 grit paper, you may like to proceed directly to awhite buffing compound. If fine scratches are visible, then you'll need to 'back off' and go to theGrey compoundbefore retrying the white.
2. Aluminum Side Cover - just dull.
Obviously, it would be a step backwards to start treating this piece by using the technique in our first example. As there is no large metal content to be removed, you could virtually dispense with the sandpapers and move directly to the polishing aspect of the part. TheBrown buffing compoundwith aSisal wheelcould be employed to see if the shine is good enough. If not, then use agrey compound, and then rework the part using the brown compound.
3. Aluminum Wheel Casting.
Many wheels are prepainted, directly over a rough sand casting. Remove the paint usingNitromors, to expose the aluminium. The 'pimples' caused by the sand cast have to be removed to flatten the metal ready for polishing. Because of the difficult contours of the wheel, it is virtually impossible to sand with a flat block, so this is whereGreaseless Compoundcomes in. Start off with the 80 grit, using aspiral sewn wheelor, for the awkward areas, a felt bob. Then proceed through the various grit sizes of Greaseless, until the metal is smooth , all 'pimples' are removed and an even 'flat' finish is achieved. The polishing should only begin once all traces of 'pimples' are gone. UseGrey Compoundfor most of the polishing work, and finally, on a fresh or cleaned wheel, buff lightly with theBrown compound.
Initial rough cutting
Professional polishers do their roughing out on a belt on the end of a 3 phase machine, obviously the home workshop isn’t going to have this feature but there are large diameter flap wheels to mount to a pigtail available in grits from 40g to 400g
Also mops can be turned into good cutting mops by the addition of Red Head Wheel cement & aluminium oxide grit, the mop is liberally coated in the water based glue and then the mop is rolled through the oxide so that the surface is coated this is then left to dry. The oxide grit is available in grits from 40g to 320g
Another useful wheel is the felt mop which can also be glued with aluminium oxide the same way.
Often to tone down the cut of the wheels a Grease compound is used on the wheel, this reduces the finish cut even more.
Polishing Mops
Where polishing mops are concerned the world is your oyster, there are many types of mops available for specific jobs, the ones that interest us mostly are Sisal, Cotton Stitched or White Close Stitch Mops & Loose Finishing Mops. Mops are available in several diameters from 5” to 12” and usual widths are 1” or 2”
Mops need to be cleaned out regularly with a rake, a rake is a double handled piece of wood with spikes on one side that is pressed against the revolving mop, a piece of wood with nails banged through it does an inexpensive and excellent job.
THE SISAL BUFFING WHEEL
Sisal is a slender, hard, cellular strand of fiber that has demonstrated its great strength and tough resiliency in the form of binder twine, cord & rope for many years. These qualities, along with its natural abrading and grease absorbing characteristics, provide an ideal buffing wheel fabric.
Sisal buffing wheels will provide both polishing and cutting action. They will remove stretcher strains, orange peel, polishing wheel grit lines, light die marks, etc. To effect a fast cut, use a sisal wheel
Polishing Compounds/Soaps
There are many manufacturers of soaps but Canning & Menzerna are about the best, Soaps are rated by the cut & gloss they give, some have a aggressive cut but low gloss while others have very little cut but have a high gloss.
A quick word about colour coding of soaps is needed as not all manufacturers use the same, It’s always best to ask your supplier which soap will give you the results you seek.
Continued:
DanielW
Member
- Messages
- 2,250
- Location
- Merseyside Straightjacket user
Normally people on here will tell you buy a polishing wheel but thats ok if you're doing a lot of polish frequently so....
I use the soap and drill mops from toolstation on my ally jobs.
http://www.toolstation.com/shop/Power+Tool+Accessories/d80/Buffing+Polishing/sd2694
Best to get the deeper scratches out first with a medium grade emery cloth then the finest grade emery and then polish with medium soap and then fine soap.
I use the soap and drill mops from toolstation on my ally jobs.
http://www.toolstation.com/shop/Power+Tool+Accessories/d80/Buffing+Polishing/sd2694
Best to get the deeper scratches out first with a medium grade emery cloth then the finest grade emery and then polish with medium soap and then fine soap.
Here is a guide for Menzerna Compounds
523LBZ MK2 Grey
This is a grey cutting compound. It has the most cut of all the Menzerna polishing compounds. Use with a sisal polishing mops, a very aggressive compound for all metals.
Cut 10 Gloss 1
523LBZ Grey
A grey cutting compound. Slightly less cut than the 523LBZ MK2 but a little cleaner. Use with sisal polishing mops.
Cut 9 Gloss 2
523BFF Grey
Grey cutting compound. Moderate cutting grey compound which leaves a better finish than both the 523LBZ compounds but will not have as much cut.
Cut 8 Gloss 3
ULTO 12 White
A cut/colour that has been formulated for stainless steel and other harder metals. Contains a special grade of abrasive that cuts and also gives good productivity. Would not recommend this compound on softer metals such as brass and copper. The reason is that the grade of abrasive being so hard can scratch non ferrous metals. This compound can be used with sisal mops or white stitch mops.
Cut 7 Gloss 5
439T Green
A cut/colour compound. Used on all metals this compound has a good cut and still leave a bright finish. It contains a special grease that binds the abrasive to mop which increases bar and mop life. A very popular mid range compound.
Cut 7 Gloss 5
P14 Classic White
A classic cut/colour compound. Used on all metals this compound has a good balance of cut and colour. Can be used with sisal or white mops
Cut 6 Gloss 6
495P White
This is a compound for harder ferrous metals such as stainless steel. Contains a special grade of abrasive that cuts and also gives good productivity. Would not recommend this compound on softer metals such as brass and copper. The reason is that the grade of abrasive being so hard can scratch non ferrous metals. This compound can be used with white mops.
Cut 4 Gloss 8
P164 Blue
A finishing compound with more colour that cut. Used on all metals this compound is commonly used as finishing compound. Gives a nice bright finish. Commonly used with White mops or Loose Mops.
Cut 4 Gloss 8
P126 Rose
Excellent finishing compound for all metals. Dry and clean, this compound can be used when high finish is needed. Use with loose finishing mops.
Cut 1 Gloss 9
ULTO 15 Yellow
Finishing compound that has been formulated for Non ferrous metals. Used with Loose finishing mops
Cut 1 Colour 9
P175 Yellow
Premium finishing compound for all metals. Very popular if you demand perfection. Use with soft loose polishing mops such as WDR grade.
Cut 1 Colour 10
WHICH WHEEL & COMPOUND ???
Use this chart to determine which wheels and compounds to use to polish different metals. This is a guide...experienced polishers will vary the materials used to suit the application and their technique. This chart serves as a good starting point for beginning polishers, but feel free to experiment.
The Sanding & Polishing process
Here will be polishing a piece of stainless bar (Aluminium being a softer material allow is to start with much finer grits)
First off the skin left from the manufacturer needs to be broken (on stainless this is the hardest task) we are using a 60 grit flapwheel here to remove the tramlines put it when it was rolled at the factory.
Once the surface is smooth and clean we move onto a 120 grit wheel, then a 180 grit wheel and finally a 320 grit wheel, It now should be looking very smooth and will have a satin appearance.
Next we move onto a Sisal mop loaded with a compound that gives a good cut but low gloss. In this case Grey soap.
We now have a surface that is very very smooth and has a semi gloss finish.
Next a Cotton Stitched mop was used along with a white compound that gives less cut but more gloss.
Final finishing is done with a Loose mop
To move the piece in the direction of the buffs rotation is called a colouring stroke, or a
Polishing stroke, to move against it is a cutting stroke.
Bits & Bobs
To get into awkward corners a multitude of small wheels are available, these comprise of small flap wheels, Sisal, Felt & Cotton stitched Bobs which are either mounted on a 6mm shaft or can be mounted on a 6mm pigtail, these can also be used with the Red Head glue and Aluminium Oxide.
All the above work very well mounted in a Die Grinder or a flexible drive and used by hand.
POLISHING METALS
IMPORTANT
The list below and a general polishing processes that are proved to work, there are other compound and mop combinations that work just as well.
There are many factors involved regarding polishing some are listed below:
A) Condition of the metal with determine where you start.
B) Speed the mops runs at.
C) Quality of the metal. Its does vary and a bad casting can cause problems.
D) Abrasives, get a good even surface with no deep scratches to ensure a deep mirror finish.
E) Make sure you remove the marks left from a previous process
F) If possible try to alter the direction of the polishing for each process, even if only by a few degrees.
G) Do not overload polishing mops with compound. You will deposit grease on the work surface.
H) Use safety equipment, glasses and dust mask. Dust is never nice. Polish outdoors if you have no extraction.
I) Vienna Lime can be used after polishing to remove light grease and finger marks etc. If the work needs degreasing then a solvent like white spirit works well.
J) If the mop becomes clogged or dirty after use has been left on shelf for a long time for example then use a mop dresser or wheel rake to bring new life into the mop. Never wash mops in water
K) Use one compound per mop. This keeps everything simple for example if you are using a sisal mop with grey compound try not to change. It is possible to change compound but make sure the old compound has been removed. Tools like mop dressers and wheels rakes are ideal for this application.
Polishing Aluminium.
Not as hard as the above metals, steel etc. When polishing aluminium if you are getting small holes that appear when you are polishing, stop. These can not polished out they are due to the casting and if you keep polishing you will get more holes appear. Best just buff up if this happens for damage limitation.
If the metal is in a poor condition then abrasives will be needed. That’s where experience of polishing comes in, looking at then metal and knowing what process you need to start at.
You will need to get the surface to 240/400 grit before you start polishing at process 1.
If the condition of metal is not too bad or you have the surface to 600 grit + then you could start at process 2.
Some people prefer to use the green compound on Process 1 with a sisal rather than the grey.
There are a couple of options on finishing, P126 Rose is a superb finisher but for that extra special job P175 can be used.
For thin sheet Aluminium there is a new fine finishing compound available 480F, this is a light green compound that is more greasy than the normal finishing compounds which keeps the surface cooler.
Process 1 (Burnishing) Grey 523LBZ compound with a sisal polishing mop
Process 2 (Prepolishing) Green 439T compound with a white close stitched polishing mop
Process 3 (Polishing) Blue P164 Compound or Rose P126 Compound with a Loose G quality
Process 4 (Finishing) P175 for super finishing with a Loose WDR quality mop
So what is a mirror finish? If you were to look at a mirror finish under a microscope it would look like a mountain range. But because the peaks and valleys are so small and close together and rounded off, they reflect light and the surface appears smooth and mirror like, although its not.
Absolute flatness is actually impossible to achieve but we can get pretty close. therefore all we are actually doing is making a series of finer and finer scratches untill we eventually round off the peaks. This is achieved by going through the abrasive grades untill we get to the finish we want. The three methods used are: Abrasive finishing polishing, Buffing or bright finishing and colouring.
The first stage is often described as 'emery bobbing' or 'scurfing' this involves the use of abrasives which cut away the surface irregularities and imperfections. It can also be done by the use of abrasive belts, flap wheels, hand rubbing blocks or abrasive cloths and papers.
The second stage is polishing or buffing and requires the use of polishing compositions and mops to produce a bright smooth finish. The term COLOURING is applied to the final polishing of metal part when again use is made of mops and polishing compositions. After all the scratches have been polished out the metal is finally 'coloured' . To make it clean and brilliant, a lime-based or rouge composition is used on the finishing mops.
Don’t try to polish in direct sunlight, it evaporates solvents before they can work, dries slip enhancers and hardens waxes. In other words, it’s harder work.
523LBZ MK2 Grey
This is a grey cutting compound. It has the most cut of all the Menzerna polishing compounds. Use with a sisal polishing mops, a very aggressive compound for all metals.
Cut 10 Gloss 1
523LBZ Grey
A grey cutting compound. Slightly less cut than the 523LBZ MK2 but a little cleaner. Use with sisal polishing mops.
Cut 9 Gloss 2
523BFF Grey
Grey cutting compound. Moderate cutting grey compound which leaves a better finish than both the 523LBZ compounds but will not have as much cut.
Cut 8 Gloss 3
ULTO 12 White
A cut/colour that has been formulated for stainless steel and other harder metals. Contains a special grade of abrasive that cuts and also gives good productivity. Would not recommend this compound on softer metals such as brass and copper. The reason is that the grade of abrasive being so hard can scratch non ferrous metals. This compound can be used with sisal mops or white stitch mops.
Cut 7 Gloss 5
439T Green
A cut/colour compound. Used on all metals this compound has a good cut and still leave a bright finish. It contains a special grease that binds the abrasive to mop which increases bar and mop life. A very popular mid range compound.
Cut 7 Gloss 5
P14 Classic White
A classic cut/colour compound. Used on all metals this compound has a good balance of cut and colour. Can be used with sisal or white mops
Cut 6 Gloss 6
495P White
This is a compound for harder ferrous metals such as stainless steel. Contains a special grade of abrasive that cuts and also gives good productivity. Would not recommend this compound on softer metals such as brass and copper. The reason is that the grade of abrasive being so hard can scratch non ferrous metals. This compound can be used with white mops.
Cut 4 Gloss 8
P164 Blue
A finishing compound with more colour that cut. Used on all metals this compound is commonly used as finishing compound. Gives a nice bright finish. Commonly used with White mops or Loose Mops.
Cut 4 Gloss 8
P126 Rose
Excellent finishing compound for all metals. Dry and clean, this compound can be used when high finish is needed. Use with loose finishing mops.
Cut 1 Gloss 9
ULTO 15 Yellow
Finishing compound that has been formulated for Non ferrous metals. Used with Loose finishing mops
Cut 1 Colour 9
P175 Yellow
Premium finishing compound for all metals. Very popular if you demand perfection. Use with soft loose polishing mops such as WDR grade.
Cut 1 Colour 10
WHICH WHEEL & COMPOUND ???
Use this chart to determine which wheels and compounds to use to polish different metals. This is a guide...experienced polishers will vary the materials used to suit the application and their technique. This chart serves as a good starting point for beginning polishers, but feel free to experiment.
The Sanding & Polishing process
Here will be polishing a piece of stainless bar (Aluminium being a softer material allow is to start with much finer grits)
First off the skin left from the manufacturer needs to be broken (on stainless this is the hardest task) we are using a 60 grit flapwheel here to remove the tramlines put it when it was rolled at the factory.
Once the surface is smooth and clean we move onto a 120 grit wheel, then a 180 grit wheel and finally a 320 grit wheel, It now should be looking very smooth and will have a satin appearance.
Next we move onto a Sisal mop loaded with a compound that gives a good cut but low gloss. In this case Grey soap.
We now have a surface that is very very smooth and has a semi gloss finish.
Next a Cotton Stitched mop was used along with a white compound that gives less cut but more gloss.
Final finishing is done with a Loose mop
To move the piece in the direction of the buffs rotation is called a colouring stroke, or a
Polishing stroke, to move against it is a cutting stroke.
Bits & Bobs
To get into awkward corners a multitude of small wheels are available, these comprise of small flap wheels, Sisal, Felt & Cotton stitched Bobs which are either mounted on a 6mm shaft or can be mounted on a 6mm pigtail, these can also be used with the Red Head glue and Aluminium Oxide.
All the above work very well mounted in a Die Grinder or a flexible drive and used by hand.
POLISHING METALS
IMPORTANT
The list below and a general polishing processes that are proved to work, there are other compound and mop combinations that work just as well.
There are many factors involved regarding polishing some are listed below:
A) Condition of the metal with determine where you start.
B) Speed the mops runs at.
C) Quality of the metal. Its does vary and a bad casting can cause problems.
D) Abrasives, get a good even surface with no deep scratches to ensure a deep mirror finish.
E) Make sure you remove the marks left from a previous process
F) If possible try to alter the direction of the polishing for each process, even if only by a few degrees.
G) Do not overload polishing mops with compound. You will deposit grease on the work surface.
H) Use safety equipment, glasses and dust mask. Dust is never nice. Polish outdoors if you have no extraction.
I) Vienna Lime can be used after polishing to remove light grease and finger marks etc. If the work needs degreasing then a solvent like white spirit works well.
J) If the mop becomes clogged or dirty after use has been left on shelf for a long time for example then use a mop dresser or wheel rake to bring new life into the mop. Never wash mops in water
K) Use one compound per mop. This keeps everything simple for example if you are using a sisal mop with grey compound try not to change. It is possible to change compound but make sure the old compound has been removed. Tools like mop dressers and wheels rakes are ideal for this application.
Polishing Aluminium.
Not as hard as the above metals, steel etc. When polishing aluminium if you are getting small holes that appear when you are polishing, stop. These can not polished out they are due to the casting and if you keep polishing you will get more holes appear. Best just buff up if this happens for damage limitation.
If the metal is in a poor condition then abrasives will be needed. That’s where experience of polishing comes in, looking at then metal and knowing what process you need to start at.
You will need to get the surface to 240/400 grit before you start polishing at process 1.
If the condition of metal is not too bad or you have the surface to 600 grit + then you could start at process 2.
Some people prefer to use the green compound on Process 1 with a sisal rather than the grey.
There are a couple of options on finishing, P126 Rose is a superb finisher but for that extra special job P175 can be used.
For thin sheet Aluminium there is a new fine finishing compound available 480F, this is a light green compound that is more greasy than the normal finishing compounds which keeps the surface cooler.
Process 1 (Burnishing) Grey 523LBZ compound with a sisal polishing mop
Process 2 (Prepolishing) Green 439T compound with a white close stitched polishing mop
Process 3 (Polishing) Blue P164 Compound or Rose P126 Compound with a Loose G quality
Process 4 (Finishing) P175 for super finishing with a Loose WDR quality mop
So what is a mirror finish? If you were to look at a mirror finish under a microscope it would look like a mountain range. But because the peaks and valleys are so small and close together and rounded off, they reflect light and the surface appears smooth and mirror like, although its not.
Absolute flatness is actually impossible to achieve but we can get pretty close. therefore all we are actually doing is making a series of finer and finer scratches untill we eventually round off the peaks. This is achieved by going through the abrasive grades untill we get to the finish we want. The three methods used are: Abrasive finishing polishing, Buffing or bright finishing and colouring.
The first stage is often described as 'emery bobbing' or 'scurfing' this involves the use of abrasives which cut away the surface irregularities and imperfections. It can also be done by the use of abrasive belts, flap wheels, hand rubbing blocks or abrasive cloths and papers.
The second stage is polishing or buffing and requires the use of polishing compositions and mops to produce a bright smooth finish. The term COLOURING is applied to the final polishing of metal part when again use is made of mops and polishing compositions. After all the scratches have been polished out the metal is finally 'coloured' . To make it clean and brilliant, a lime-based or rouge composition is used on the finishing mops.
Don’t try to polish in direct sunlight, it evaporates solvents before they can work, dries slip enhancers and hardens waxes. In other words, it’s harder work.
Well to warn you now not every aluminium will produce a good polish, the cheaper/softer the aluminium the more likely quality/lasting will be less.
I've designed just a few (a hell of a lot really over the years) ali injection moulds. In fact I have done polishing on ali injection moulds for a few weeks once to mirror finish.
How you polish it by hand.
Start with a low grit - if the scratches aren't deep maybe 800 you will get away with but without seeing it I can't tell, you may well need 400.
Anyway the first paper you use only go in one direction straight.
Next grade up do it in the perpendicular direction - 90 degree to the first again only in straight lines. You use it until you remove all the lines from the previous paper in the other direction
Carry on doing this up to say 1500 or 2000.
Then use polishing soap to give mirror finish, or some FINE metal polish from down the frauds.
I've designed just a few (a hell of a lot really over the years) ali injection moulds. In fact I have done polishing on ali injection moulds for a few weeks once to mirror finish.
How you polish it by hand.
Start with a low grit - if the scratches aren't deep maybe 800 you will get away with but without seeing it I can't tell, you may well need 400.
Anyway the first paper you use only go in one direction straight.
Next grade up do it in the perpendicular direction - 90 degree to the first again only in straight lines. You use it until you remove all the lines from the previous paper in the other direction
Carry on doing this up to say 1500 or 2000.
Then use polishing soap to give mirror finish, or some FINE metal polish from down the frauds.
SmartWerks
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- chester
As previously mentioned, flatten back the scratches, then finish with autosol.
Otherwise it's a lot of outlay, i have all the tackle. It's dirty but satisfying work but you need to invest a bit of time and money if the parts are past basic restoration.
SmartWerks
Otherwise it's a lot of outlay, i have all the tackle. It's dirty but satisfying work but you need to invest a bit of time and money if the parts are past basic restoration.
SmartWerks
DanielW
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- Merseyside Straightjacket user
What is all the tackle mate??
DanielW
Member
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- Merseyside Straightjacket user
you cannot protect aluminium from outside elements,you might get away with it using a coating of laqaur but eventually erosion will take place after a while.
Manufacture give it a heavy powder coating and even that breaks down because the oxidisation starts its process.
I wouldn't call that polished either. What Mr Shiney did is polished as is this close up of a fuel tank which is made from one of the softer flavours of aluminium that apparently doesn't polish up well
