Much like painting and welding, preparing metal for powder coating is multi step process that must be followed in order to have the best results. If any of these steps are missed or not done properly your end product will risk having flaws.
What Can Be Powder Coated?
During the curing process the part will reach 400+ ºF, this means that only certain materials can actually be coated. With that said any parts with plastic, rubber, gaskets of any kind and wiring will have to be completely removed before starting to prep the metal. With that said, anything with moving parts must be taken apart and coated separately, then reassembled after. It the powder is applied across a moving joint the curing process will lock the two together. Depending on the type of part you will be powder coating, different levels of disassembly will be required. For example a valve cover or set or coil spring will not require any disassembly since there are no moving parts. More complex parts like alternators, Carburetors, and Steering components will require a lot of time devoted to making sure all of the pieces are properly taken apart and sealed.
First your part must be fully disassembled and any pieces that will not be coated removed.
Since I will be powder coating these engine brackets, removing all the bolts was the only disassembly needed .
If, for example, you were powder coating a carburetor, all of the openings must be plugged with rubber plugs to prevent powder from getting into any of the crevasses and openings. Additionally any moving parts must be either removed or taped up using high temp masking tape. When disassembling complex parts like this its important to take pictures along the way. Check out this article which talks about the importance of taking pictures during your project.
The next step in the process is cleaning the metal. There are a few methods of doing this but first you always want to remove any dirt or grease by using Eastwood PRE Painting Prep, spray a liberal amount on a rag and wipe down the surface of the part. this will remove dirt, oil, grease and grime from the outside of the part. During this step you will not need to worry about removing any paint or other coatings that might be on the surface, this will be dealt with next.
This step will take care of any coatings that are currently on the part. By far most effective method would be to Media Blast the part but if you do not have access to a blaster a good sanding with 80-120 grit Sand Paper or a Flap Disc on an Angle Grinder should be able to handle the job of stripping off any coatings on the metal.
Now that any previous coatings are removed, use a blow gun to remove any dust. Instead of wiping the part down, you should completely spray down the part with PRE Painting Prep and then let it air dry. If you were to wipe it down with a rag there is a potential that contaminants on the rag or towel could be transferred to the part.
If you want all of the exposed metal coated then you can skip this step. For most parts there are certain areas that you will want bare metal to remain. In order to mask off these areas the use of a special type of masking tape is needed. Paint Masking Tape will not hold up in the high temperatures that the oven will reach. High Temp Masking Tape is the answer to this dilemma, coming in sizes from 1/8" to 2" this tape will be able to cover any size area needed.
Just make sure you don't touch the part with your bare hands it is ready for powder coating.
Check out the Eastwood Blog and Tech Archive for more How-To's, Tips and Tricks to help you with all your automotive projects. If you have a recommendation for future articles or have a project you want explained don't hesitate to leave a comment.
- James R/EW