View Full Version : DA downward pressure - how much is enough?

11-15-2010, 04:30 AM
Hi everyone,

Been searching through the forums trying to find out how much downward pressure is required to achieve swirl removal by da polisher and am having no luck. I am relatively new to DA polishing and have watched many how-to videos, all have helped me to get swirls out but I still feel unsure as to how much downward pressure to apply when polishing. Is there any trick to help with this?



11-15-2010, 04:45 AM
When I started (not that long ago actually) I read that 5 lbs was about the right amount of pressure, and the way you learn this is to place the machine on a bathroom scale, read it's weight, and then apply 5 more lbs of pressure. And practice this for a little while till you get to know what 5 lbs feels like and can reproduce it at will.

Now it gets a bit trickier doing side (vertical) panels, like doors and such, because it feels different to apply pressure sideways. But with practice you'll get it. :xyxthumbs:

11-15-2010, 09:25 AM
I started off under machine weight under advice from Mothers forum, however, through this forum have found (and gotten much better results) with 15-20 lbs of force. Depends on the pad you are using and how much it deforms.

Mike Phillips
11-15-2010, 09:45 AM
You vary the pressure depending upon what you're trying to do...

If you're trying to remove swirls and scratches then you're trying to remove a little paint in an effort to flatten or level out the surface.

To remove paint you need the pad rotating under pressure and it's the downward pressure that's going to "engage" the abrasives with the paint forcing them to take little bites out of the paint.

The PC and it's variants, all way around 5 to 6 pounds with a pad and chemical. This weight, in other words, the weight of the machine is not enough to remove swirls effectively. Maybe if you have nothing to do for the rest of you life but most of us want to get in and get the job done.

Back in 2005, I wrote an article on Meguiar's Online on how to use the G100 to remove swirls and in it I recommended 15 to 20 pounds of downward pressure, this has been questioned by many people over the years but I'm happy to say that over the last 5 years the forum consensus has vindicated this recommendation and for the correction step, you want to use around 15 to 20 pounds of downward pressure.

You MUST maintain pad rotation at the same time so some factors that will effect how hard you can push down are,

Pad thickness
Pad Diameter
Backing plate size
Product lubricity
Amount of product
Temperature and humidity
Panel shape

Thin pads rotate better and easier than thick pads. Been beating this drum for a long time and now Lake Country, Surbuf, Meguiar's and Griot's Garage all have thinner pads on the market with the new Microfiber pads being the thinnest.

Pad size needs to really be around the 5.5" range in diameter, any smaller and it will take to long to buff out a car and while larger pads will rotate under pressure, there's a huge increase in total surface area as you increase diameter and this increased surface area puts an extra burden on DA Polisher to try to keep the pad rotating.

So mark out an area to work on, keep it around the 20" by 20" working size, and then with a clean pad and ample product, start doing your section passes holding the pad flat and maintaining firm downward pressure but no so much that the pad stops rotating.

Mike Phillips
11-15-2010, 09:53 AM
This is another article I wrote on MOL, it lists the most common problems first and then the solutions... these tips and techniques would also apply to any DA Polisher that uses a free floating spindle assembly, thus the Griot's Garage 6" ROP, the new PC 7424XP, the Shurhold, the DeWalt DW443 and any variation or knock-off of the PC

Tips & Techniques for using the G110v2, G110, G100, G220 and the PC Dual Action Polisher (http://meguiarsonline.com/forums/showthread.php?t=20874)

(These are all similar tools)

After teaching hundreds of classes here at Meguiar's, there are some common mistakes most people make when trying to remove swirls and scratches with a dual action polisher. Most of them have to do with technique.

Here's a list of the most common problems

Trying to work too large of an area at one time.
Move the polisher too fast over the surface.
Too low of speed setting for removing swirls.
Too little pressure on the head of the unit.
Too much pressure on the head of the unit so the pad quits rotating.
Not keeping the pad flat while working your product.
Too much product, too little product.
Not cleaning the pad often enough.
Here's a list of the solutions in matching order,

Shrink your work area down, the harder the paint the smaller the area you can work. The average area should be and average of about 16" by 16" up to 20" by 20" or so. 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.
For removing defects out of the paint you want to use what we call a Slow Arm Speed. It's really easy to move the polisher too quickly because the sound of the motor spinning fast has a psychological effect to for some reason want to make people move the polisher fast. Also the way most people think is that, "If I move the polisher quickly, I'll get done faster", but it doesn't work that way.
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, again... 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 rotating over the paint as well as the combination of time, (slow arm speed), together with the diminishing abrasives, the foam type, and the pressure to remove small particles of paint which is how your remove below surface defects like swirls or scratches. It's a leveling process that's somewhat difficult because the tool is safe/gentle while in most cases, modern clear coat paints are harder than traditional single stage paints and this makes them hard to work on. This is also why people get frustrated, they don't understand paint technology, all they know is their paint swirls easy and getting the swirls out is difficult and thus frustrating.
For the same reason as stated in #3, people are scared, or perhaps a better word is apprehensive, to apply too much pressure and the result of too little pressure is no paint is removed thus no swirls are removed.
Just the opposite of item #4, people think that by pushing harder on the polisher they can work faster and be more aggressive, but the truth is the clutch in the tool is a safety mechanism to prevent burning and will cause the pad to stop rotating, thus less cleaning or abrading action and once in a while this will lead a person to then post on the forum something like this, "Hey my pad doesn't rotate". There needs to be a balance of enough pressure to remove defects and keep the pad rotating but yet not too much pressure as to stop the rotating action. This balance is affected by a lot of things, things like type of chemical, some chemicals provide more lubrication and the pad will spin easier, curved surfaces or any raise in body lines will tend to stop the pad from rotating. This is where experience on how to address these areas comes into play or you do the best you can and move on. It's not a perfect tool, nor a perfect system, but it's almost always better than working/cleaning by hand.
Applying pressure in such a way as to put too much pressure to one side of the pad will cause it to stop rotating and thus decrease cleaning ability.
Too much product over lubricates the surface and this won't allow the diminishing abrasives to do their job plus it will increase the potential for messy splatter as well as cause pad saturation. Too little product will keep the pad from rotating due to no lubrication and there won't be enough diminishing abrasives to do any work. Again it's a balance that comes with experience, or another way of saying this would be it's a balance that comes with hours of buffing out a car to learn what to do and what not to do. Information like what you're reading here is just an edge to decrease your learning curve. Hope this is helping.
Most people don't clean their pad often enough and most of the time the reason for this is because they don't know they're supposed to clean their pad often and they don't know how to clean their pad. Again, that's why this forum is here to help you with both of these things. You should clean your pad after every application of product or every other application of product, your choice, most of the time cleaning your pad after every other application of product works pretty well. It enables you to work clean and enables the foam pad, the polisher and the next application of fresh product too all work effectively. How to clean your pad will be addressed below sooner versus later, but not at the time of this posting. (Sorry, I'm behind a keyboard, not a video camera
The first 4 are the most common.

Mike Phillips
11-15-2010, 09:53 AM
Here's how to do a "Section Pass" when trying to remove swirls, scratches and other below surface paint defects.

How to do a Section Pass
[ame=http://www.youtube.com/watch?v=Q70g83mnTn4]YouTube - How to do a "Section Pass" with a Porter Cable 7424XP[/video]

Visit Autogeek's YouTube Channel for more YouTube Videos (http://www.youtube.com/autogeek)

When talking about machine polishing on discussion forums or even in detailing classes, the below questions always comes up,

What's a pass?
How many passes do I make?
What's a section pass?

The definition of a pass
There are two definitions of the word pass as it relates to machine polishing with any type of machine.

Single Pass
A single pass is just that. It's when you move the polisher from one side of the section you're buffing to the other side of the section you're buffing. That's a single pass.

Section Pass
A section pass is when you move the polisher back and forth, or front to back with enough single overlapping passes to cover the entire section one time. That's a section pass.

In most cases if you're removing any substantial below surface defects you're going to make 6-8 section passes to the section youíre working before you either feel comfortable you've removed the defects or you're at the end of the buffing cycle for the product you're using.

Buffing Cycle
The buffing cycle is the amount of time you are able to work the product before the abrasives have broken down, (if youíre using a product that uses diminishing abrasives), and/or the product begins to dry and you lose the lubricating features of the product. Different products have different buffing cycles depending upon the type of abrasives used in the formula and the different ingredients used to suspend the abrasives and provide lubrication.

Factors that affect the buffing cycle include,

Ambient temperature
Surface temperature
Size of work area
Type of machine
Type of pad material
Wind or air flow surrounding the car
Amount of product used

Wet buffing technique
Most compounds and polishes should be used so that there is enough product on the surface to maintain a wet film while the product is being worked. The wetness of the product is lubricating the paint as the abrasives abrade the paint and cushion or buffer the abrading action so the abrasives donít simply scour the finish leaving behind swirls and scratches.

Dry Buffing Technique - Buffing to a dry buff
There are some products on the market where the manufacture recommends buffing the product until it dries. As the product dries youíll tend to see some dusting as the product residue becomes a powder and the paint will have a hard, dry shine to it.

Although some manufactures recommend this, itís important to understand whatís taking place at the surface level as you buff to a dry buff. As the product dries, in essence you are losing the lubricating features of the product and as this happens friction and heat will increase. As friction and heat increases, so does the risk of micro-marring the paint or instilling swirls either by the product residue or the pad material and/or a combination of both.

While we trust that the manufacture knows their products best, when we take a close look at what it means to buff on a delicate surface like an automotive clear coat, it doesnít make sense to run a buffing pad on top of the paint without some kind of wet film to lubricate the paint at the same time. We always recommend that you follow the manufacturer's recommendations and use your own judgment.

Everyone new to buffing wants to be told some easily identifiable sign that they can use to tell when it's time to stop buffing and it's not that simple, so here's an indicator I've always used and taught to others,

Wet film behind your path-of-travel
As you're making a single pass with the polisher, the paint behind the path of travel of the buffer should have a visible wet film on it. If the paint behind the pad is dry and shiny, you've run out of lubrication and you're dry buffing. Turn the polisher off. Wipe the residue off and inspect using a Swirl Finder Light to make sure you didn't dull or mar the paint, you usually won't cause any harm, but pay attention when your running the polisher and don't buff to a dry buff. If you do, you can quickly re-polish that section by cleaning your pad and adding a little fresh product and making a few new section passes.

Remember, in most cases the goal is UMR or Uniform Material Removal. The reason for this is so that you remove an equal amount of paint over each section and in turn over the entire car. In order to do this you need a method that you can control and duplicate and for most people following a back and forth, side-to-side pattern works because itís easy to remember, easy to do and easy to duplicate.

The above video segment is a 4 minute clip filmed during the extended version of How To Remove Swirls using any Dual Action Polisher like the Meguair's G110v2 (http://www.autogeek.net/meguiars-dual-action-polisher-g110.html) and the Griot's Garage ROP (http://www.autogeek.net/griots-random-orbital-polisher.html) and all models of he Porter Cable Dual Action Polisher, including the PC7424XP (http://www.autogeek.net/dual-action-polishers.html), PC7424, PC7336, G100

How to Remove Swirls using the Porter Cable 7424XP or any D.A. Polisher (http://www.palmbeachmotoring.net/ascg-videos/porter-2-20-10.html)


11-15-2010, 12:45 PM
Mike, I can totally see you mapping a 'post article' script to a MIDI drum kit and sitting there drumming out posts including the 'staple' how-to sections.

I would be curious if you are using macros, or just have a one note doc full of your previous how-to posts.

Mike Phillips
11-15-2010, 02:43 PM
Mike, I can totally see you mapping a 'post article' script to a MIDI drum kit and sitting there drumming out posts including the 'staple' how-to sections.

I would be curious if you are using macros, or just have a one note doc full of your previous how-to posts.

Somethings I have coded in BB Code in Notepad and then just copy and paste when in the "Editor Mode" in vBulletin.

Other things come from my article list and I just go to "Editor Mode" and copy and paste the BB Code

And other things are threads I've bookmarked and then using the "Editor Mode", copy and paste the BB Code...

And then sometimes I just type fast...

For Lurkers reading this or Newbies to vBulletin... here's an article on the "Editor Mode"

How to use the "Editor Mode" to break a single quoted message up into smaller quoted sections (http://www.autogeekonline.net/forum/off-topic/20690-how-use-editor-mode-break-single-quoted-message-up-into-smaller-quoted-sections.html)

This is for anyone that's not sure how to use the Editor Mode in vBulletin to tweak their code or to break a large section of quoted material into smaller bites-size sections.


It also shows you how to use the up and down arrows to shrink or increase the length of your message box for easier typing.


11-15-2010, 05:22 PM
Thanks for all the speedy replies everyone! I've definitely learnt a lot. I'm sure everyone agrees-Mike you are a detailing library: your advice is always greatly appreciated, thank you! Gonna try Silverstone's scale method asap and apply a good 6-9 kg (my metric country) downward pressure and get used to it.