I hijacked my reply from an old MOL thread (circa 2005).
Here's the entire thread if you want to check it out:
What causes the buffer to hop? - Car Care Forums: Meguiar's Online
A very SHORT explanation...
I know what you're going through. Anyone that's using foam pads has encountered the same 'hopping' problem, so don't worry. Let's go over the dynamics of pads.
Wool pads are very forgiving and easy to control in comparison to
foam pads. Wool pads
glide as they change shape. The wool strings lay upon each other as the pad spins. Since the strings are individually thin,
they easily change overall pad thickness (as varied pressure is applied and buffer angle is changed). In other words, they conform to flat or curved surfaces rather easily.
Some reasons why foam pads hop:
1. Foam pads are squishy, and have a natural tendency to rebound.
All those tiny air pockets purposely designed into the pad allow
compression and
rebound (If you squeeze the pad between your fingers, it'll try to return to its natural shape).
When the pad is placed on the paint surface and the buffer is throttled, the foam pad twists against the paint initially. Once it planes, it returns to its natural shape (close to it, anyway). The amount of pressure you are applying to the buffer also determines the amount of distortion the pad will encounter. Push hard, and the pad flattens. Of course, it wants to rebound to its natural shape.
Therefore, a foam pad needs something to control its rebound (Just as a car needs shock absorbers to control suspension springs).
Effectively, YOU become the shock absorber. You must learn the amount of pressure needed to keep the pad shape consistent. If bouncing does occur, you'll have to lift up on the buffer (to reduce pressure momentarily), or change the angle of attack.
On that topic: Assuming that downforce remains the same, if you change the angle of the pad to a more aggressive one, the pounds per square inch applied to the paint will be increased because less pad is touching paint, but the same force is being applied, right?
I hope I've explained this properly. If I did, you can easily understand why compression and rebound would cause foam pad hop.
2. Too much buffing polish applied to the surface.
Whereas a wool pad easily cuts through excess buffing polish (a weedwhacker effect takes place), a foam pad does not easily cut through excess polish.
Foam pads work well because they are made to glide along the surface rather than cut into it. If too much polish is applied, the pad cannot cut through, and instead rides upon it.
The excess polish either gums up on the paint, or saturates the pad. When this happens, the foam pad does not glide along smoothly- It grips and then releases (even at 1200 r.p.m. this can happen many times per second). Severe compression and rebound occurs, and VOILA! - Your buddy
pad bounce stops by for a quick visit.
3. Not enough polish applied to the painted surface.
If not enough polish is applied to the paint, the foam pad does not glide. Instead, the rubbing action creates heat (which in turn causes the pad to 'hook up' (like a drag slick!). If this is a common problem for you, I feel sorry for the state of your wallet... Repainting will definitely be in your future.
4. Foam Pad Saturation.
When too much product is repeatedly applied, eventually the polishing oils and/or solvents will enter the foam pad and saturate it. When this happens, the integrity of the pad is compromised.
The foam material may become 'soft' and non-pliable (it won't keep it's original shape). It'll become gummy.
As a rule, you should carry
two to three times more foam pads on hand as compared to wool pads. Rotating your pads through the buffing process will allow them to air dry, evaporate solvents, and minimize thermal breakdown.
It is very important to keep polish build-up to a minimum on the pad itself. Use a soft brush designed for foam pad cleaning to remove residue, and if you must wash a foam pad, use only car wash solution or baby shampoo, as they are typically pH balanced (and won't attack the glue holding the velcro on the pad). To dry, roll the pad into a terry cloth towel and squeeze. Allow to air-dry.
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