Personal Recommendation For IPA
If you want to chemically strip paint to remove any compound or polish residues so that you can accurately see the true condition of the paint after any correction steps, then I recommend using approximately a 10% dilution of IPA to water solution. This is a safe approach to remove any residues masking the true results of your process to the paint without the risk of causing any harm.
You can also opt to use Mineral Spirits instead as they will also remove compounding and polish residues.
Checking Your Test Spot vs Checking the Entire Car
Theoretically, if your use IPA to chemically strip your Test Spot and after stripping and inspecting the results look good to your eyes, then theoretically if you duplicate the same correction process over the rest of the panels you will also remove all the defects and leave the same finish behind that you saw in your Test Spot.
Assuming all the panels have the same type of paint, then you shouldn't have to continue stripping all the paint on each panel, just keep doing the same good work you did for your test spot and trust in your skills and ability.
You can check each square inch as you work around the car to make sure you're doing as good of work over the rest of the car as you did in your test spot, that's an option and choice each person can make. I tend to check my Test Spot and if it looks good then simply repeat the process over the rest of the car and trust in my skill and ability to duplicate my process over and over again with little variation.
Chemically Removing Waxes and/or Paint Sealants
Note this article is addressing the dilution strength for removing compounding and/or polishing lubricating oils sometimes called fillers during the paint correction steps. You can also use this to try to remove any previously applied wax or paint sealant, but while I was speaking with one of my chemists friends about this topic they told me that Isopropyl Alcohol is not effective at removing some polymer products.
Since there's no way of knowing at the molecular level what's on the surface before you wipe, and no way of knowing if 100% of everything has been removed off the surface after you wipe, therefore there's no way of knowing if IPA, (in any form) is effectively removing 100% of any previously applied wax or paint sealant. You can hope... you can assume... but you can't know 100%
If you're dead set on removing any previously applied wax or paint sealant by chemically stripping the paint, then a combination of using both a 10% solution of IPA to Water followed by wiping with Mineral Spirits should remove most, if not all, of any previously applied wax or paint sealant.
Personal Recommendation For Removing Waxes and Paint Sealants
To remove any previously applied wax or paint sealant, I recommend using a light paint cleaner or a light polish applied by hand or machine. A light paint cleaner or abrasive polish will effectively remove any previously applied wax or paint sealant AND leave the paint looking clear and glossy. I call this working forward in the process because the goal is to create beauty.
Chemically stripping the paint will tend to dull the paint; it certainly doesn't increase gloss and clarity. You don't see the dulling effect unless you're working on black paint and repeat the process multiple times. Since not everyone works on black paint, and you're not going to make stripping your car's paint a daily routine, it could be you won't see the dulling effect on your car's paint but it does take place.
Wiping a clear coated black finish over and over and over again with any type of solvent isn't going to make the top clear layer of paint more and more clear, it's going to do the opposite, that is dull it down.
So chemically stripping paint is what I call working backwards in the process. I, personally, prefer to work forwards in all my detailing projects but do understand the reasons why some people want to chemically strip their car's paint, or their customer's car's paint, and each person can decide what the best approach is for their needs.
And again, since you're not chemically stripping the paint as a "practice" but only during a detailing session, the dulling effect is not an issue, but I wanted to point it out just for the most detail oriented detailing enthusiasts or Pro Detailers reading this article.
rops:
