Best Material for Magnetic Car Signs & How Car Magnets Work


Photograph of the back left side of a gray car that has a yellow "Support our troops" ribbon magnet next to the tail light.

David Sharpe writes: We have a flatbed printer and solvent printer and we are looking for the best magnetic product to use for Car Magnets. One of our clients just had some of the ones that we are using blow off of her car.

1st: When Considering the Best Material for Magnetic Car Signs, the Thickness of the Magnetic Sheet Used for Magnets on Cars Matters

Unfortunately, this issue is not as uncommon as you would think, mostly because there are a number of possible contributing factors. However, let’s start by addressing your question specifically. When making magnetic car signs we first have to be concerned with the thickness of the magnetic sheet. Its thickness is directly related to its strength (pounds of pull).

How Car Magnets Work

It has been universally accepted throughout our industry that the minimum acceptable thickness for automobile signs is .030”, also commonly referred to as 30mil.  Anything less than .030” may not provide the pounds of pull required to withstand the external forces an automobile sign is subjected to.

With that being said, there are a number of other issues which may be causing your customer’s car signs to blow off, the most common of which involve cleaning and storage of the sign.

2nd: Proper Storage Of Magnetic Car Signs Matters

When not in use, the best way to store your magnetic sign is by laying it flat on a steel surface. If this is not a possibility, you can roll it up, but be sure that the printed side of the sign faces outward. If you roll it up the other way, you are introducing ‘memory’ in the magnet which could prevent the edges of the magnet from lying flat while on your car. With the edges lifting up from the surface of your car, the possibility of wind getting underneath the magnet and basically ‘prying’ it up are much more realistic. This occurrence will obviously result in the sign eventually blowing off.

3rd: Keep Your Car Magnet And Automobile Clean

The other most common contributing factor is the cleanliness of both the magnet and the automobile. If not properly maintained, you can end up with debris being trapped between the magnet and car. This issue is detrimental in two ways, the first of which is similar to the ‘memory’ issue discussed earlier. Larger debris can create channels through which wind can penetrate underneath the magnet and ‘pry’ it off.  Debris can also introduce ‘air gaps.’ These are gaps between the magnet and the surface to which it is trying to attach. This situation will essentially decrease the holding force of the magnet and possibly allow it to blow off. The magnet and automobile surfaces should be properly prepared and maintained to avoid this issue.

For more information and specific instructions on cleaning please click on the following link: Car Magnet Cleaning. Thank you for your question. If there’s anything else we can answer please let us know.

If you have additional questions or if you’d like to learn more about custom car magnets, contact us here or call us now at 800.747.7543!