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Will Car Touch-Up Paint Shrink When It Dries?

Touching up your car's paint has never been this cheap, easy, or as effective as it's ever been. In the olden days, even a tiny stone chip might require sending your car over to a paint shop, and you'll soon leave there with a hefty repair bill in your hands. Nowadays, though, you can go to a website, and order an entire repair kitto match your car's exact colour for as little as £30.

And that goes for the best touch-up solutions on the market! With an hour or two of your time, you can have that chip or scratch filled in without leaving your garage. Technology has truly come a long way. But despite this ease, some questions do linger that remains unanswered, and one that might make this touching up the process a whole lot less confidence-inspiring on the surface.

One such puzzle to solve is the subject around whether or not your paint touch-up solution shrinks when it dries up. Naturally, you'd want to know this, along with the complex science around paint touch-ups to make sure you do as good of a job as possible. Thankfully, we aim to answer this, step by step. First, let's look at how you'd go about touching up your car's paint..

Step 1: Before we can begin to touch up the paint, we'll need to clean the soon-to-be touched up area. This involves getting some water and a mild car washing soap. You could instead use rubbing alcohol to get rid of a protective wax layer. Either way, dry the area thoroughly with a microfibre cloth after washing it.

Step 2 The next step would be applying the touch-up paint, whether it's through the use of a paint pen or a brush applicator. This is subject to how big the chipped or scratched area is (the larger the surface area; it's best to use a brush), and what comes with your touch-up kit. Apply layer by layer, and being careful to wait for each single layer coating to dry before applying the next one.

Step 3 The length of time it would take for the paint to dry will vary depending on which touch-up kit you use, as its paint formulation may take more or less time to cure. It will also vary based on the climate you're in with its temperature and humidity. Some paint touch-up kits require as little as just 5 minutes to dry.

Step 4 If you've applied too much touch up, then you'll need to remove the excess paint. You can do this in a variety of ways according to how big the excess "blob" is, and judging by how dry the paint is. If it's too dried up, you can use an acetone paint remover, lacquer thinner, or nail polish remover. Apply it carefully to remove the excess touch up paint with a Q-tip or cotton swab. Some touch-up kits may even have a blending solution to help you get rid of excess paints.

Step 5: When the base coat is complete, know that the upper-most clear coat layer isn't always necessary. Although, some paint touch-up repair kits do include it, so you may as well apply a thin layer of clear coat on top of the smoothened base coat. After this, you can let the clear coat dry, and then perhaps consider a polish and wax to maintain the glossy finish.

Do Touch-Up Paints Shrink?

With those five steps outlined, you know now roughly the processes at work when doing a full paint touch-up. However, that's not yet answered our question. For this, let's take a look back at Step 2, in how during the application of the touch-up paint, you're implored to wait for each layer of the paint's base coat to dry before adding another coat (and more) on top? 

Well, that's because like any other type of liquid or fluid, paint does indeed shrink when they dry. Touch-up paints are no different, in that their overall volume will decrease once they're dried up from while it was still wet. Nevertheless, this is never an issue during paint touch-up repairs, as it drying up won't affect the finished look of the final paint at all, nor does it cause complexities.

The only thing that's required of you is to add another layer or more on top of now-shrunken coating to make up for the lost volume, and thus ensure that the touch-up area is level with the rest of the car's surface. This is one reason why you're asked to let one (regardless of whether it's the body filler below, the base coat, or the top-most clear coat) dry before adding another one.

The number of layers you'll need to add will depend on how deep the chip is. If you add one coat, let it dry, and there's still a fairly deep pit once that first coat is dry, you may have to add another layer. Let that one dry, and maybe add another one (or more) coatings on top as necessary. After that, you can proceed with the following steps as if nothing ever happened.

Conclusion

In summary, we can say that yes, your car's touch up paint will shrink when it dries. But this is a normal step of the process in touching up your car anyways. Depending on which repair kit you go with, and what sort of paint mix they use, you may need some minutes, hours, or upwards of days to let the paint completely dry, and for the shrinkage to fully manifest. 

This goes for every layer of paint and pre-paint, such as the filler, primer, base coat, mid coat (for a triple-layer paint finish), and the clear coat on top. All you need to do is let the paint shrink and dry, and then keep reapplying more layers of paint on top to even out the chipped or scratched area, and bring it to level out with the intact surface of your car's paintwork.