Choosing your test spot

[rockford33]

I did a search, but came up with many, many posts with "test spot" in them, so I apologize if this has been covered before and I missed it.

I recently watched Mike's video on doing a test spot. In the video, he just did a spot in the center of the hood (I understand for demonstration purposes only). Unless I missed it in the video, I didn't hear/see anything about how he chose the test spot. Since a typical car will have different levels of swirls on it (hood might be real bad, roof not so bad), how do you choose a test spot?

If you choose the worst looking area, you might be too aggressive on other areas that aren't as bad (therefore not using the "least aggressive pad/polish" theory). If you choose a spot that is not that bad, you might not have the right combo to get out swirls, RIDS, etc. elsewhere on the car.

I guess you would go with an average area (not super swirled/scratched, but with some defects)? This way, areas with worse defects might need a little more work/passes, etc. and areas with very light or minimal defects would not be overly corrected. Does that sound right?

Thanks,
Neil

[Flash Gordon]

The decklid is my customary test spot

[Setec Astronomy]

I dunno, I think cars tend to be fairly "evenly" swirled, unless someone has taken a kitchen pad to a particular spot(s). I think the choice of hood or decklid is because it's easy to see your results; then you're sure your process works.

[Flannigan]

Horizontal panels are usually worse off than vertical panels IME. I always do a test spot on the hood and fender just to be sure.

[LegacyGT]

It depends on the car, if it is swirled out evenly, anywhere works. If there is a particularly bad area I will usually do a second test spot there so I know what to switch to when I get to that area.

[Mike Phillips]

If you choose the worst looking area, you might be too aggressive on other areas that aren't as bad (therefore not using the "least aggressive pad/polish" theory). If you choose a spot that is not that bad, you might not have the right combo to get out swirls, RIDS, etc. elsewhere on the car.

Great points but too deep to try to cover in a video, at least at that time...

That was one of the first videos we made after I left Meguiar's and came to Autogeek, we filmed that in the old garage as the new studio didn't even exist. That video was chopped way down from the final cut and had I tried to go into all the different ways to do a test spot it would have ended up cut out also.

Like Flannigan said, usually the horizontal surfaces are in worse condition than the vertical surfaces and more visually noticeable.

Two options...

1. If you dial in a process that works on the hood chances are really good it will take care of the vertical panels without a hitch, just move around the car and don't worry about it as for most people, you're not removing that much paint.

2. If it's important to you to use the least aggressive product to get the job done so that you leave the most paint on the car, then do multiple test spots. You can also vary the aggressiveness of the product you're using by changing pads.

With SMAT products you can stop anytime during the buffing cycle so it's not an issue if you start out using something really aggressive. With most DAT products, at least the ones we talk about on this forum, the polishes are not so aggressive that it's a concern either as the diminishing abrasives will have broken down after you make your normal section passes.

It's a great question!

[rider9195]

When I do my test spots, I tend to do one on the trunk or the hood. The cars I have done tend to have the heavier swirling on the horizontal surfaces, and the vertical surfaces tend to have less swirling in some cases. So then I know what pad, product, and technique I will need to use to remove all the imperfections. So there will be a slight different technique doing a less swirled area. Either less section passes, less aggressive pad, etc.

[Mike Phillips]

The most important thing is to test before buffing out an entire car only to find out you're not getting the results you want and hope for...

If your combination of pad, product and technique cannot make one small section look good then it certainly isn't going to make the entire car look good and a person can always come back to the forum to share what they're seeing and get some suggestions as to how to proceed next.

[Jons6.7]

Even for us hobby detailers this is very important. After doing a small test area on the wife's dark blue metallic trailblazer SS. I did the the whole hood and font side panels only to get all done and find I was not in fact getting everything out.

Guess I get to learn again. After watching the videos and seeing the before and after you guys post, I have a whole new level of respect for the effort that goes into doing this right.

[Mike Phillips]

Wrote this years ago on MOL, still applies today...


Here's a list of the most common problems

1. Trying to work too large of an area at one time.
2. Move the polisher too fast over the surface.
3. Too low of speed setting for removing swirls.
4. Too little pressure on the head of the unit.
5. Too much pressure on the head of the unit so the pad quits rotating.
6. Not keeping the pad flat while working your product.
7. Too much product, too little product.
8. Not cleaning the pad often enough.

Here's a list of the solutions in matching order,

1. 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.
2. 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.
3. 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.
4. 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.
5. 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 Free Floating Spindle Bearing Assembly 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.
6. 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.
7. 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.
8. 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.