Help me understand DA speed

[Riff]

Just got the Harbor Freight DA with Lake Country 5.5" pads. Used it for the first time yesterday on my pretty neglected but still not terrible 2003 Mazda MPV. Silver hides swirls good!

I used an orange pad with Meguiars Ultimate Compound, then white pad with Meguiars Ultimate Polish. I'm pretty happy with the results considering my first time and this is just practice for my other vehicles.

From reading up here, I used speed 5 for the compound and 4 for the polish but now that I'm thinking about it, wouldn't a high speed and very slow arm speed be better for a polish? It seems like a high speed, very light pressure and slow arm speed would give a better finish.

Can anybody explain why use a higher speed for compound and a slower speed for polish?

[rolop6]

Depending on the severity of the car, the pad and the compound/polish is the speed that needs to be used. If your correcting a severely neglected finish your need the speed to cut through the clear(5-6). If your polishing minor defects (4-6) might work. A wax (3-4), cleaner wax (4-6). You have to determine what speed you need based on the defects and the combo of pad and polish/compound. That's what the test spot if for, to help determin pad, product and speed necessary to get the results you want.

[Riff]

Thanks. So a higher speed might work for a polish. I'll try that out on my next test run.

[Kyle_Elantra]

You're right, less pressure can potentially lead to a better finish.
I suggest using your normal amount of pressure for your first couple of passes, then letting up on the pressure and letting the weight of the machine do the work on your last few passes.

You don't want to use no pressure at first - this will not allow the polish to do its work. I've always had success finishing the polishing step by letting up on the pressure.

As for the speed, you want to be more aggressive when compounding compared to polishing. When polishing you're really just refining the haze or tiny scratches remaining from compounding - you do not need high speed and aggressiveness to accomplish this.

Moderate machine speed, slow arm speed, and lessening pressure will help you refine your polishing.

Of course, as stated above, do a test spot and realize that every paint is different. Sometimes higher speed for polishing makes sense, but - for me and the paints I've worked on - it usually doesn't.

[Riff]

Thanks!

👍

[allenk4]

Depending on the severity of the car, the pad and the compound/polish is the speed that needs to be used.

If your correcting a severely neglected finish your need the speed to cut through the clear(5-6).

If your polishing minor defects (4-6) might work.

A wax (3-4),

cleaner wax (4-6).

You have to determine what speed you need based on the defects and the combo of pad and polish/compound.

That's what the test spot if for, to help determin pad, product and speed necessary to get the results you want.

There are simply too many variables to state this speed for compound...this speed for polish, etc.

-Compound aggressiveness

-SMAT or DAT

-Pad Aggressiveness

-Temperature

-Pressure

-Number of passes

-Hard clear-coat or soft

-Single stage paint


Mike Phillips has loads of information on the Forum on how to do a proper Test Spot.

This is IMO, the single most important thing to learn.

It will allow you to get the best possible end result, while saving time and clear-coat.

[Tato]

I'd like to add that pressure or no pressure may not be determined just by the task at hand, it's good to avoid making 'generalizations'... pressure is added to engage abrasives 'against' paint, and I use it even with finishing polishes and finishing pad.

Even if using a finishing polish like Menzerna SF4000, it has a cutting ability of 4/10 on Menzerna scale. That's almost half abrasiveness of a compound, so I see no reason to not engage the abrasives over paint with some added pressure.

As your polishing cycle goes (3-4 first passes) and you see (yes, SEE!) abrasives signal of properly broken down (product turning transparent), then you may reduce pressure to do the last 2 passes and finish in a glorious manner.

See, it's not 'crazy pressure' as a grinding process, but in order to work abrasives down you'll need to properly maintain your pad firm and flat on surface, and ease on pressure at end of cycle.

Some see heat as the main responsible for abrasives break down. I don't see this way, and avoid heat at any cost (although impossible, it's a collateral effect of polishing process). I see the friction as a more important aspect to properly work product down.

IMO, if you barely exert any pressure, odds are you'll not work product in a effective manner, and you'll have many cons on that, like not being effective enough on your approach, and not working abrasives properly may leave you with a difficult to remove residue. Also, your perfect finish may be sacrificed by this ineffective approach.

Again, this is not a generalization as well, but trying to understand how to work a product to polish and effectively remove small amounts of paint is the way to go.

This approach I've told above may be totally different if using Meguiar's SMAT products where abrasives have a defined size and won't break down to smaller size throughout polishing cycle.

The same goes for speed. I've saw a thread earlier that demonstrated how slow speed (but plenty) may promote (theoretically, at least) better finish.

I'll try to find it and place it here.

Hope that helps.

Kind Regards.

[Tato]

Here it is:

Post #10 of this thread.

***In advance, I don't know if Autopia thread can be shared here, if so, please, forgive my fault and cancel my post. Thank you in advance.

KBM- Pad Priming and Supplemental Wetting Agents - Guide to Detailing - Autopia

Kind Regards.

[allenk4]

Here it is:

Post #10 of this thread.

***In advance, I don't know if Autopia thread can be shared here, if so, please, forgive my fault and cancel my post. Thank you in advance.

KBM- Pad Priming and Supplemental Wetting Agents - Guide to Detailing - Autopia

Kind Regards.

Autopia and AutoGeek are both owned by Palm Beach Motoring Group

[Tato]

Thank you for info!!