Is Clay before UC Needed ??

[JonH]

My cars are in generally good condition. I have read a lot about claying before UC. Unless I have tree sap or some other major contaminant why would I need to clay before UC. I use a PC DA with the UC. The UC leaves me a very smooth surface to polish and wax. What would the

clay do that UC does not.

[Murr1525]

Re: Is Clay before UC Needed ??

Well, if the surface doesnt need clayed, then it doesnt need clayed. It only needs to be clayed if there are bonded on things to remove.

However, if there are bonded on things to remove, you can have two things happen. One, the pad can actually bounce over them, leaving them behind. Or, they can break off and stick to the pad, and if it is a rough particle, end up causing swirls over the car.

[Michael Stoops]

Re: Is Clay before UC Needed ??

Claying only really needs to be done on an as needed basis. While you can remove some bonded contaminants, or at least light ones, with a buffer and strong paint cleaner, if the level of contamination is approaching severe then this isn't the most efficient or safe way to go about it. Heavy contaminants may be removed, to some extent at least, via machine buffing but doing so compromises the paint cleaners ability to do its primary job - removing below surface defects.

For routine maintenance on a daily driver that isn't getting much accumulation of bonded contaminants in the first place, and depending on your overall expectations, you may want to just machine buff and wax and call it good. It's a bit of a short cut, yes, and we have to stress that your expections will dictate whether this approach makes much sense or not. Light colored vehicle, dark color, looking for a show car shine or just keeping it looking decent. All things to consider here, but if you're really looking to do things right, if you want the best possible finish you can get, you should probably clay before machine polishing. If the contamination is light then it may really only be on the horizontal surfaces anyway, and if that's the case then even a large sedan can be clayed on those surfaces in just a few minutes. Personally, we'll opt for clay every time whether it's light contamination or heavy. Of course if the paint is perfectly smooth there's nothing to gain from claying, but rarely is that the case when it's time do some serious machine buffing.

[JonH]

Re: Is Clay before UC Needed ??

Thanks for the replies. What are considered "bonded contaminants"? My guess would be tree sap, tar residue and other "visible" things. Maybe I am missing the definition, can they be things you can't see upon examination?

[gtrspeed]

Re: Is Clay before UC Needed ??

Jon - that's correct. Tree sap, tar, iron particles, industrial fallout, paint overspray... All of those things are considered "surface-bonded contaminants," and while normal washing isn't going to remove them, the pressure put on the surface of the car during compounding could cause a few particles to come loose and get dragged across the paint as you work, creating scratches on their own.

If your paint does not feel smooth to the touch, then it probably needs to be clayed. You can also slip a plastic baggie over your hand and then gently feel the paint - this will enhance your ability to feel those contaminants. As Michael said, they primarily build up on the horizontal surfaces (hood, roof, trunk lid), but you may also find contamination on the lower half of the car body, as it's more exposed to road grime and the associated gunk.

[Blueline]

Re: Is Clay before UC Needed ??

then it may really only be on the horizontal surfaces anyway, and if that's the case then even a large sedan can be clayed on those surfaces in just a few minutes. .

IMHO..I don't think there is ever a time for the vertical surfaces, except the front, to be clayed. Then again, I am not a professional, just a realist. (and probably a tad lazy)

[Shawn T.]

Re: Is Clay before UC Needed ??

IMHO..I don't think there is ever a time for the vertical surfaces, except the front, to be clayed. Then again, I am not a professional, just a realist. (and probably a tad lazy)

I've actually seen on most vehicles that the rocker panels and the sections right behind the tires are by far the worst parts on cars. They are, in my experience, just as rough or rougher than the horizontal surfaces before claying.

[Michael Stoops]

Re: Is Clay before UC Needed ??

Thanks for the replies. What are considered "bonded contaminants"? My guess would be tree sap, tar residue and other "visible" things. Maybe I am missing the definition, can they be things you can't see upon examination?

Technically, "above surface bonded contaminants" includes anything that does not come off with a regular soap and water wash. While that include things that can easily see like tree sap and tar residue, it also includes those things you can not see but can definitely feel; fine paint overspray, industrial fallout, etc. It's those things you can not see that are actually most common and are the things that make paint feel rough to the touch even though visually it may appear almost perfect. Clay is designed to remove those fine particles but may not work so well on the larger stuff like large blobs of tree sap, paint that was splashed up from running over freshly painted stripes in the road, or those large bits of tar that you can see from twenty feet away. Methods other than clay are usually required to remove those larger things.

IMHO..I don't think there is ever a time for the vertical surfaces, except the front, to be clayed. Then again, I am not a professional, just a realist. (and probably a tad lazy)

It really all depends on exposure and maintenance. While it makes sense that fallout is going to have a greater potential to stick to the horizontal surfaces (it does, after all, fall down and not sideways), if a vehicle is neglected long enough then even those vertical surfaces can end up feeling pretty rough. We have a feeling that you're taking pretty good care of your car on a regular basis as opposed to the "average consumer" who maybe waxes their car once a year and washes it "sometimes". In that case, you're far from lazy and are actually helping to prevent the accumulation of these deposits in the first place. And it's always easier to do preventive maintenance than to do corrective work.