Mike Phillips
Active member
- Dec 5, 2022
- 51,004
- 7
Wood Sanders as Paint Polishers
I've been answering this question as long as the the Porter Cable DA Wood Sander gone Paint Polisher has been around. It usually goes like this,
I don't have a PC 7424 but I have a similar orbital wood sander, can I just use this?
Hey... it's a great question. I mean it kind of makes sens right? If one brand of wood sander works to polish paint won't all wood sanders work to polish paint?
the answer is "no".
What determines whether a wood sander will polish paint or not is if the wood sander in question has the power to rotate a foam pad under pressure. I don't mean it make the pad spin in a circle, I mean when you're pushing down firmly, trying to remove swirls out of a car's hard clear coat finish will it abrade the paint enough to level it and thus remove the swirls and scratches and again... the answer is "no".
That's why the Porter Cable rocketed in the sales category starting back in the early 1990's.
This discussion also comes up when talking about the first Griot's paint polisher introduced, not the current unit in the second generation, but the very first unit they introduced which was also a wood sander. See this article,
Especially post #16
First Generation Griot's Polisher
(Won't rotate a pad under pressure - Useless for removing swirls - New version is the way to go)
And this article too...
Griot's Garage 6" won't accept Lake Country 5" Backing Plate?
Wood sanders are designed to spin a THIN disc of sanding paper. That's a completely different task than rotating and oscillating a foam or fiber pad with liquids being applied to it.
I would recommend anyone reading this thinking about using their wood sander to polish paint to at least give it a try because,
"You don't know what you can do until you try"
So try.
I was sent a PM today asking about this wood sander,
Instead of replying in the PM where one set of eyeballs will see the information, my normal protocol is to write an article where hundreds, maybe thousands of eyeballs will be able to read and use the information into the future. This is a better use of what's called, typing time.
Be sure to somehow mark your backing plate or the back of the buffing pad so your eyes can easily see if the pad is in fact rotating under pressure. Like this,
Video: Mark your backing plate to make it easy to see pad rotation
Here's a quick video that show how and why to mark your backing plate to see and monitor pad rotation while doing any correction or polishing steps.
It's also important to maintain pad rotation with PC style tools when using a one-step cleaner/wax or AIO type product on neglected paint.
It's not vital to maintain pad rotating when applying a finishing wax or finishing paint sealant to a finish that you've just buffed out.
And when you get ready to test out your wood sander on car paint, be sure to do a test spot like this,
How To Do a Test Spot
A Test Spot
A Test Spot is where you take the products, pads, tools and your best technique and buff one small section, usually on a horizontal panel, to test out these things to see if they'll create the results you want, hope for and dream about in some cases.
If your choice of products, pads, tools and technique works to remove the defects and restore the finish to your expectations, then theoretically you should be able to duplicate the same process to the rest of the vehicle and create the same results.
If your choice of products, pads, tools and your technique doesn't create the results you want, hope for and dream about then you can come to the forum and post what you're seeing and we'll do our best to help you tweak your technique, substitute different products, pads and/or tools to see you through to success.
Tape Line
It helps to place a piece of painter's tape on a horizontal surface, usually the hood or trunk lid but if you want to be more discreet you can use the roof. Then only work on one side of the tape line as this will make it very easy for you to see visual changes due to the distinct demarcation line between before and after results.
Tape-line using 3M Green Painter's Tape
Before and after results along the demarcation line
Don't buff directly on the tape-line, I only do that for a dramatic PICTURE, see this article,
The LINE ---> How to avoid the line!
And if you're new to machine polishing, be sure to read my troubleshooting guide before you get into trouble, that is before you turn the polisher on so you know what to do and how to do it before you start.
DA Polisher Trouble Shooting Guide
Tyler, age 15 removing swirls using a Porter Cable 7424XP Dual Action Polisher
When you're first starting out machine polishing and learning to use a DA Polisher it's common to have questions about your results and your results are directly tied to your technique.
Here's a list of the most common problems,
1. Trying to work too large of an area at one time.
Shrink the size of your work area down. You can't tackle to large of an area at one time. The average size work area should be around 20" by 20". Most generic recommendations say to work an area 2' by 2' but for the correction step, that's too large. You have to do some experimenting, (called a Test Spot), to find out how easy or how hard the defects are coming out of your car's paint system and then adjust your work area to the results of your Test Spot. The harder the paint the smaller the area you want to work.
2. Moving the polisher too fast over the surface.
For removing defects out of the paint you want to use what we call a Slow Arm Speed. It's easy and actually natural for most people new to machine polishing to move the polisher quickly over the paint but that's the wrong technique. One reason I think people move the polisher too quickly over the paint is because they hear the sound of the motor spinning fast and this has psychological effect which causes them to match their arm movement to the perceived fast speed of the polisher's motor.
Another reason people move the polisher too quickly over the paint is because they think like this,
"If I move the polisher quickly, I'll get done faster"
But it doesn't work that way. Anytime you're trying to remove swirls, scratches, water spots or oxidation using a DA Polisher you need to move the polisher s-l-o-w-l-y over the paint.
3. Using too low of speed setting for removing swirls.
When first starting out many people are scared of burning or swirling their paint, so they take the safe route of running the polisher at too low of a speed setting but this won't work. The action of the polisher is already g-e-n-t-l-e, you need the speed and specifically the pad oscillating and rotating over the paint as well as the combination of time, (slow arm speed), together with the abrasives, the pad aggressiveness, and the downward pressure to remove small particles of paint which is how your remove below surface defects like swirls or scratches.
Removing below surface defects is a leveling process where you need the abrasives to take little bites out of the paint and to get the abrasives to take these little bites with a tool that uses a Free Floating Spindle Bearing Assembly you need all of the above factors working for you including a high speed setting.
4. Using too little downward pressure on the head of the polisher.
For the same reason as stated in #3, people are scared, or perhaps a better word is apprehensive, to apply too much downward pressure to the polisher and the result of too little pressure is no paint is removed thus no swirls are removed.
5. Using too much downward pressure on the head of the polisher so the pad quits rotating.
If you push too hard you will slow down the rotating movement of the pad and the abrasives won't be effectively worked against the paint. You need to apply firm pressure to engage the abrasives against the paint but no so much that the pad is barely rotating. This is where it's a good idea to use a permanent black marker to make a mark on the back of your backing plate so your eyes can easily see if the pad is rotating or not and this will help you to adjust your downward pressure accordingly.
Correct technique means finding a balance of applying enough downward pressure to remove defects but not too much downward pressure as to stop the rotating movement of the pad.
This balance is affected by a lot of factors like the lubricity of the product you're using, some compounds and polishes provide more lubrication than others and this makes it easier to maintain pad rotation under pressure.
Another factor that can affect pad rotation are raised body lines, edges and curved surfaces as anytime you have uneven pressure on just a portion of the face of the pad it can slow or stop pad rotation. This is where experience comes into play and experience comes from time spent behind the polisher.
6. Not holding the polisher in a way to keep the pad flat while working your compound or polish.
Applying pressure in such a way as to put too much pressure to one edge of the pad will cause it to stop rotating and thus decrease abrading ability.
7. Using too much product or using too little product.
Too much product hyper-lubricates the surface and the result is that abrasives won't effectively bite into the paint but instead will tend to skim over the surface. Overusing product will also accelerate pad saturation as well increase the potential for slinging splatter onto adjacent panels.
Too little product will means too little lubrication and this can interfere with pad rotation.
Again there needs to be a balance between too much product and too little product and finding this balance comes from reading articles like this one, watching videos an most important, going out into the garage and putting in time behind the polisher and as you're buffing with specific product and pad combinations, pay attention to pad rotation.
8. Not cleaning the pad often enough.
Most people simply don't clean their pad often enough to maximize the effectiveness of their DA Polisher. Anytime you're abrading the paint you have two things building up on the face of your buffing pad,
Pad Cleaning Articles
Why it's important to clean your pads often...
How to clean your foam pad on the fly
How to use the Grit Guard Universal Pad Washer
Tyler, age 15 machine applying a paste wax using a Porter Cable 7424XP Dual Action Polisher
Summary
So I know that if you already have an orbital wood sander after doing some lurking and reading on the forum you're wondering if the old wood sander in the garage or shop can be used to buff the swirls out of your daily driver and the answer is,
If it has a hook interface on the backing plate, then get a foam buffing pad, I'd recommend a thin, 5.5" foam pad like listed in the below article, and... try.
If you cannot maintain good pad rotation with firm pressure then you will not be able to remove swirls. It would be faster to work by hand. You can apply a finishing wax but that's a lot different than actually removing a little paint to level out the surface.
Also get a copy of my how-to book, it goes over EVERYTHING you need to know to detail a car using a DA Polisher, Rotary Buffer, Cyclo Polisher and Flex 3401.
5 inch Backing Plates on Meguiar's, Griot's and Porter Cable DA Polishers
5 1/2 inch and 6 inch Buffing Pads on Autogeek's Online Store
I've been answering this question as long as the the Porter Cable DA Wood Sander gone Paint Polisher has been around. It usually goes like this,
I don't have a PC 7424 but I have a similar orbital wood sander, can I just use this?
Hey... it's a great question. I mean it kind of makes sens right? If one brand of wood sander works to polish paint won't all wood sanders work to polish paint?
the answer is "no".
What determines whether a wood sander will polish paint or not is if the wood sander in question has the power to rotate a foam pad under pressure. I don't mean it make the pad spin in a circle, I mean when you're pushing down firmly, trying to remove swirls out of a car's hard clear coat finish will it abrade the paint enough to level it and thus remove the swirls and scratches and again... the answer is "no".
That's why the Porter Cable rocketed in the sales category starting back in the early 1990's.
This discussion also comes up when talking about the first Griot's paint polisher introduced, not the current unit in the second generation, but the very first unit they introduced which was also a wood sander. See this article,
Especially post #16
First Generation Griot's Polisher
(Won't rotate a pad under pressure - Useless for removing swirls - New version is the way to go)
And this article too...
Griot's Garage 6" won't accept Lake Country 5" Backing Plate?
Wood sanders are designed to spin a THIN disc of sanding paper. That's a completely different task than rotating and oscillating a foam or fiber pad with liquids being applied to it.
I would recommend anyone reading this thinking about using their wood sander to polish paint to at least give it a try because,
"You don't know what you can do until you try"
So try.
I was sent a PM today asking about this wood sander,
Instead of replying in the PM where one set of eyeballs will see the information, my normal protocol is to write an article where hundreds, maybe thousands of eyeballs will be able to read and use the information into the future. This is a better use of what's called, typing time.
(How many people reading this have sent me a PM when they were a new forum member and in my answer also received a polite request to please post questions to the "pubic side" of the forum? It's always meant to be taken in a kind and well meaning manner and I've been replying to PM's like this since at least 2004, that almost 10 years now because most people new to forums don't know exactly how they work... at first...
Can I get a witness?
)
Anyway, I've been given probably half a dozen orbital wood sanders to test in my life and none of them will do what the Porter Cable 7424 will do nor the other various versions modeled after it. But you can always give it a try. Can I get a witness?
)
Be sure to somehow mark your backing plate or the back of the buffing pad so your eyes can easily see if the pad is in fact rotating under pressure. Like this,
Video: Mark your backing plate to make it easy to see pad rotation
Here's a quick video that show how and why to mark your backing plate to see and monitor pad rotation while doing any correction or polishing steps.
[video=youtube_share;QM8PnDooZP8&hd=1"]How To Check Pad Rotation on a DA Polisher -...[/video]
It's also important to maintain pad rotation with PC style tools when using a one-step cleaner/wax or AIO type product on neglected paint.
It's not vital to maintain pad rotating when applying a finishing wax or finishing paint sealant to a finish that you've just buffed out.
And when you get ready to test out your wood sander on car paint, be sure to do a test spot like this,
How To Do a Test Spot
A Test Spot
A Test Spot is where you take the products, pads, tools and your best technique and buff one small section, usually on a horizontal panel, to test out these things to see if they'll create the results you want, hope for and dream about in some cases.
If your choice of products, pads, tools and technique works to remove the defects and restore the finish to your expectations, then theoretically you should be able to duplicate the same process to the rest of the vehicle and create the same results.
If your choice of products, pads, tools and your technique doesn't create the results you want, hope for and dream about then you can come to the forum and post what you're seeing and we'll do our best to help you tweak your technique, substitute different products, pads and/or tools to see you through to success.
Tape Line
It helps to place a piece of painter's tape on a horizontal surface, usually the hood or trunk lid but if you want to be more discreet you can use the roof. Then only work on one side of the tape line as this will make it very easy for you to see visual changes due to the distinct demarcation line between before and after results.
Tape-line using 3M Green Painter's Tape
Before and after results along the demarcation line
Don't buff directly on the tape-line, I only do that for a dramatic PICTURE, see this article,
The LINE ---> How to avoid the line!
And if you're new to machine polishing, be sure to read my troubleshooting guide before you get into trouble, that is before you turn the polisher on so you know what to do and how to do it before you start.
DA Polisher Trouble Shooting Guide
Tyler, age 15 removing swirls using a Porter Cable 7424XP Dual Action Polisher
When you're first starting out machine polishing and learning to use a DA Polisher it's common to have questions about your results and your results are directly tied to your technique.
Here's a list of the most common problems,
1. Trying to work too large of an area at one time.
2. Moving the polisher too fast over the surface.
3. Using too low of speed setting for removing swirls.
4. Using too little downward pressure on the head of the polisher.
5. Using too much downward pressure on the head of the polisher so the pad quits rotating.
6. Not holding the polisher in a way to keep the pad flat while working your compound or polish.
7. Using too much product or using too little product.
8. Not cleaning the pad often enough.
Here's a list of the solutions in matching order, 2. Moving the polisher too fast over the surface.
3. Using too low of speed setting for removing swirls.
4. Using too little downward pressure on the head of the polisher.
5. Using too much downward pressure on the head of the polisher so the pad quits rotating.
6. Not holding the polisher in a way to keep the pad flat while working your compound or polish.
7. Using too much product or using too little product.
8. Not cleaning the pad often enough.
1. Trying to work too large of an area at one time.
Shrink the size of your work area down. You can't tackle to large of an area at one time. The average size work area should be around 20" by 20". Most generic recommendations say to work an area 2' by 2' but for the correction step, that's too large. You have to do some experimenting, (called a Test Spot), to find out how easy or how hard the defects are coming out of your car's paint system and then adjust your work area to the results of your Test Spot. The harder the paint the smaller the area you want to work.
2. Moving the polisher too fast over the surface.
For removing defects out of the paint you want to use what we call a Slow Arm Speed. It's easy and actually natural for most people new to machine polishing to move the polisher quickly over the paint but that's the wrong technique. One reason I think people move the polisher too quickly over the paint is because they hear the sound of the motor spinning fast and this has psychological effect which causes them to match their arm movement to the perceived fast speed of the polisher's motor.
Another reason people move the polisher too quickly over the paint is because they think like this,
"If I move the polisher quickly, I'll get done faster"
But it doesn't work that way. Anytime you're trying to remove swirls, scratches, water spots or oxidation using a DA Polisher you need to move the polisher s-l-o-w-l-y over the paint.
3. Using too low of speed setting for removing swirls.
When first starting out many people are scared of burning or swirling their paint, so they take the safe route of running the polisher at too low of a speed setting but this won't work. The action of the polisher is already g-e-n-t-l-e, you need the speed and specifically the pad oscillating and rotating over the paint as well as the combination of time, (slow arm speed), together with the abrasives, the pad aggressiveness, and the downward pressure to remove small particles of paint which is how your remove below surface defects like swirls or scratches.
Removing below surface defects is a leveling process where you need the abrasives to take little bites out of the paint and to get the abrasives to take these little bites with a tool that uses a Free Floating Spindle Bearing Assembly you need all of the above factors working for you including a high speed setting.
4. Using too little downward pressure on the head of the polisher.
For the same reason as stated in #3, people are scared, or perhaps a better word is apprehensive, to apply too much downward pressure to the polisher and the result of too little pressure is no paint is removed thus no swirls are removed.
5. Using too much downward pressure on the head of the polisher so the pad quits rotating.
If you push too hard you will slow down the rotating movement of the pad and the abrasives won't be effectively worked against the paint. You need to apply firm pressure to engage the abrasives against the paint but no so much that the pad is barely rotating. This is where it's a good idea to use a permanent black marker to make a mark on the back of your backing plate so your eyes can easily see if the pad is rotating or not and this will help you to adjust your downward pressure accordingly.
Correct technique means finding a balance of applying enough downward pressure to remove defects but not too much downward pressure as to stop the rotating movement of the pad.
This balance is affected by a lot of factors like the lubricity of the product you're using, some compounds and polishes provide more lubrication than others and this makes it easier to maintain pad rotation under pressure.
Another factor that can affect pad rotation are raised body lines, edges and curved surfaces as anytime you have uneven pressure on just a portion of the face of the pad it can slow or stop pad rotation. This is where experience comes into play and experience comes from time spent behind the polisher.
6. Not holding the polisher in a way to keep the pad flat while working your compound or polish.
Applying pressure in such a way as to put too much pressure to one edge of the pad will cause it to stop rotating and thus decrease abrading ability.
7. Using too much product or using too little product.
Too much product hyper-lubricates the surface and the result is that abrasives won't effectively bite into the paint but instead will tend to skim over the surface. Overusing product will also accelerate pad saturation as well increase the potential for slinging splatter onto adjacent panels.
Too little product will means too little lubrication and this can interfere with pad rotation.
Again there needs to be a balance between too much product and too little product and finding this balance comes from reading articles like this one, watching videos an most important, going out into the garage and putting in time behind the polisher and as you're buffing with specific product and pad combinations, pay attention to pad rotation.
8. Not cleaning the pad often enough.
Most people simply don't clean their pad often enough to maximize the effectiveness of their DA Polisher. Anytime you're abrading the paint you have two things building up on the face of your buffing pad,
- Removed paint
- Spent product
Pad Cleaning Articles
Why it's important to clean your pads often...
How to clean your foam pad on the fly
How to use the Grit Guard Universal Pad Washer
Tyler, age 15 machine applying a paste wax using a Porter Cable 7424XP Dual Action Polisher
Summary
So I know that if you already have an orbital wood sander after doing some lurking and reading on the forum you're wondering if the old wood sander in the garage or shop can be used to buff the swirls out of your daily driver and the answer is,
If it has a hook interface on the backing plate, then get a foam buffing pad, I'd recommend a thin, 5.5" foam pad like listed in the below article, and... try.
If you cannot maintain good pad rotation with firm pressure then you will not be able to remove swirls. It would be faster to work by hand. You can apply a finishing wax but that's a lot different than actually removing a little paint to level out the surface.
Also get a copy of my how-to book, it goes over EVERYTHING you need to know to detail a car using a DA Polisher, Rotary Buffer, Cyclo Polisher and Flex 3401.
5 inch Backing Plates on Meguiar's, Griot's and Porter Cable DA Polishers
5 1/2 inch and 6 inch Buffing Pads on Autogeek's Online Store