Choosing the right type of paint is a very important aspect when dipping. There is not really a one paint fits all paint out there, but some are far more versatile than others. For example: you can use a basic 1K aerosol paint on an xBox controller but you wouldn't want to use that same 1K aerosol paint on your auto rims. However, you could use a 2K paint on both, your auto rims and xBox controller. To better explain why, have a look below to get a better understanding of paint types.
Just a side note, we are not going to cover every aspect of paints, the process or the differences in enamels vs lacquers vs acrylics in this. Just covering some basics... for now at least.
Single Stage Coatings
This means that the base does not require a clear coat. These can be found in both, 1K and 2K paints. You can add a clear coat for added durability and depth.
Two Stage Coatings
This is a paint that requires a base and clear coat. The base will provide the coloring while the clear coat provides the finish (glossy or flat) along with durability.
1K Paints
These are paints that are ready to use and usually what you will find in an aerosol can. They do not require any hardeners, activators or catalyst and they can air dry.
2K Paints
These are paints that need to be mixed with a hardener, activator or catalyst. This makes them more durable against chemicals, weather and UV (ultra-violet light.. think of sun light). These types of paints have recently been introduced into the aerosol industry with the addition of the two-chamber aerosol can. This allows the base and hardener, activator or catalyst to be stored in the can in separate chambers. When you are ready to use, you simply puncture the chamber seal which allows the two components to mix. This gives you the durability of a 2k paint in the convenience of an aerosol can.
Another aspect to consider is the actual paint. Not all paints will work the same in the dipping process. Some will have a longer dip window (amount of time between being applied and when film will start having trouble bonding in the dip process). Some paints are actually designed for the hydro dipping process. This means that the base is designed to work with the activator to allow for a good bond between the ink in the film and the base coat.
Not using a paint that is compatible with hydro dipping can lead to complications. One big problem that will arise is your film will not stick and will fall off when you rinse or just not stick at all. This comes from the paint rejecting the needed adhesion of the ink in the film due to the paint being fully cured (applied to long ago). An example of this would be trying to dip to an auto part that has the OEM paint on it. The paint would be to hard/cured for the activator to do its job in bonding the films ink to the base. But if you applied a fresh coat, then it would dip successfully. Now, this is not saying that you can't dip to something that has was painted a while ago or to OEM paint. Just means that you have a much higher chance of it not working.
Clear coats are your final step in the painting process. These help to protect the dipped design from scuffing or rubbing off along with protecting it from UV rays which can fade coloring in your film design and paint. Your clear coat will also be what allows you to have a flat or glossy finish. As with you base, keep in mind what you are dipping and use the correct clear coat type to protect it. A 1K clear will work wonders on your gaming controller, but you would want an automotive grade 2K clear for auto parts.
Whatever you are dipping, be sure to consider your paint carefully and make you you choose the right paint for your application.