Among all of the car products you typically see on a store shelf, isopropyl alcohol is usually not one of them. You may also see it as Isopropanol – or more commonly, rubbing alcohol. They usually can be found in the first aid section in a few different strengths usually anywhere from 70% to 99%.
When it comes to the detailing world, isopropyl alcohol is a pretty versatile product that can really help to bring restore the original surface of your vehicle when used with clays. In this blog, I’ll detail a few reasons why you would want to use this product.
So, what exactly does it do?
On a molecular level, IPA (as it’s commonly called) generally is mainly used for removing non-polar compounds which are basically anything from fats to oils, to gasoline as opposed to non-polar compounds like water or ammonia.
It’s used often as a household cleaner due to these properties (i.e. for cleaning grease spots clothes) but can also be used to remove smells. Most detailers use it for its cleaning properties in order to remove substances that aren’t easily removed (like waxes or sealants).
Here are a few common uses for it that you may not already know:
#1 – Removing Wax or Sealant from Painted Surfaces
Probably the most common use of isopropyl alcohol that I see is for when people need to remove a wax or sealant from the car prior to compounding/polishing. This is especially important for any kind of paint correction you may be doing, since the surface of the vehicle needs to be clean of any oils, waxes or residues throughout this process.
Keep in mind that most car wash soaps do a pretty good job at removing wax every time you wash, so hitting it with an IPA wipedown every time I wouldn’t recommend.
Typically only before you apply compound/polish is an IPA wash necessary.
When removing scratches or blemishes (paint correction) in certain areas of the vehicle, you just want to make sure that these products are not interacting with anything other than than the clear coat. Like leftover wax.
#2 – Removing Haze from a Windshield, Window, or Mirror
This is probably one of the safest and most effective uses of isopropyl alcohol for non-detailers in my opinion because it is an effective method for clearing up an oily or waxy windshield without applying products that just don’t work well.
Many detailing sprays that I have used (even on windshields) still leave streaks, which could be partly due to oily residue already on the windshield or the actual product being used. Isopropyl alcohol is great for cutting through all of that oil that you may not be able to see or remove with other products.
Since you’re not dealing with a clear coat, using the alcohol as-is on clear surfaces like a headlight lens is not really a huge deal. I would still mix it with some water just to make it easier to apply.
#3 – Removing Sticker Residue
If you’re detailing a vehicle with an old bumper sticker or decal on the back glass, try using isopropyl alcohol while you’re at it. While products like Goo-Gone also work pretty well, IPA is excellent for this type of application.
I’ve found that it helps to let the alcohol penetrate into the pores of the paper, and it generally will come off. Other products like Goof-off (not to be confused with Goo-gone) are a lot stronger and contain acetone, which will strip paint off from not-clear coated surfaces, and any rubber or vinyl surface. IPA is typically the safer option for this residue.
#4 – Headlight Lens Restoration
For most headlight lens restoration kits, or DIY sandpaper alternatives, isopropyl alcohol can be used between stages to eliminate dust. Starting with 300-400 grit sandpaper, dried on UV coating will begin to come off, leaving a dusty white chalk on the lens.
Once the headlight scratches begin to be removed with this wet sanding process, IPA is used as the very last step to remove any compound, polish, or dust that may still be on the headlight lens.
It really acts as a cleaning agent once the lens is clear before a UV coating is applied.
#5 – Removing Polish Residue
As with headlights, another good use for isopropyl alcohol is for removing polish. As an example, once polish is applied after compounding to remove a white scratch, the surface may appear to be blemish free if the polish is hiding the scratch in any way.
By using the alcohol you can get a better estimation of what exactly the final result it. I’ve found that when using some over the counter ‘polishes’ like Scratch Doctor, the scratches seem to disappear until several weeks later when the polish begins to wear off.
A drop or two of IPA solution is an easy way to check to see that your compounding and polishing really did remove the scratch.
Can It Damage Paint?
When mixed with water to the proper ratio, IPA solutions are typically fine for vehicles as long as they are used properly. Over time, can 70-80% concentrations soften the clear coat? Yes, but a lot of products can do this when used improperly.
If you’re a little fuzzy on some of the terminology and products used to protect clear coats (like waxes, coatings, etc.), check out this article I wrote: Compound vs Clay, Polish & Glaze! 7 Products to Understand.
With that being said, many people advise you stay away from applying any IPA to any freshly painted surface or for those with no clear coat (older vehicles). This can cause swelling or soften the clear coat.
When diluted with water, the risks go down significantly and really isn’t as big of a deal as many people seem to think. Of course, there are better alternatives if you are prepping the surface for paint.
Prepping a Surface for Paint? Use a Body Solvent Instead
If working in body shops or painting large panels, you really want to go with a product like Prep-all, Blackfire Crystal Coat Paint Prep, or even a product like Dupli-color paint prep because they are specifically designed for this type of application.
You’ll probably also find that IPA solutions evaporate rather quickly and do not contain a surfactant (which will reduce the drag when applying it).
That is why some people I have seen use water plus a surfactant with their IPA mixtures. Water provides some lubrication, but it’s really not meant to be a paint-prep.
What to Keep in Mind
Keep in mind, that isopropyl alcohol is not a bad product for beginners (when used correctly), because it is super-cheap and actually cleans better than many products. That being said, make sure you dilute it properly.
- Somewhere between 10-25% IPA to water is what most people recommend as a starting point.
- The softer the clear coat the lower the percentage you should use.
- Never use undiluted isopropyl alcohol as it will begin to eat away at the clear coat over time
- Use it on an as-needed basis in sections
- No need to apply any pressure to painted surfaces – the alcohol will do the work
- The alcohol percentage you purchase does not matter as long as you dilute it correctly.
- Purchase a spray bottle and distilled water to use with the alcohol
- If concerned about your current clear coat levels, check out this video on YouTube for tips on measuring it.
In general, thousands of people use isopropyl alcohol in some way or another, although there are some that prefer not to ever use it on paint. Regardless of what you decide to do, it does serve a purpose for many detailers and car enthusiasts in one way or another.
Have anything to add? Be sure to let us know in the comments!