Where is powder coating best used?

Because  powder tends to orange peel or form irregular surface contours,  powder looks the best when coated over curved or irregular metal surfaces  such as frames, wheels, oil tanks, calipers and engine parts.  Their physical geometry makes these powdercoating irregularities much less objectionable.  Over large low-crowned or flat surfaces, the surface irregularities intrinsic to powder coating are more noticeable.                         

However, textured or lower gloss colors show less surface irregularities and can often look as smooth as paint. 

On hot surfaces such as cylinders, blocks and covers, powder is probably the best coating to use because after curing, the powder is not as adversely affected by high heat as paint.

If powdercoated surfaces are not as smooth as paint, then why should I choose powder over wet paint?

For much sheet metal such as motorcycle tanks, fenders or any larger, low crowned or flat metal, paint is often preferred since it can be block sanded  and buffed to a smooth finish.    However, paint has some weaknesses.  It is easier to chip and scratch than powder.  Once the film is broken, such as with a stone chip, paint is then easier to peel from its underlying substrate, (either primer/surfacer or metal), exposing more of the base to corrosion.  One of powdercoating’s strengths is its ability to strongly adhere to the underlying subtrate (metal in most cases) .  If powder were to chip, the break in the powder film doesn’t weaken the surrounding powder.  It still adheres to the metal and the chip won’t get progressively larger.     
           
Other strengths of powder are its abrasion and chemical resistance.  The bond of powder to its substrate is resistant to most solvents including gasoline, salt water, and brake fluid, although the surface finish quality can be degraded.  It’s the durability of powder that makes it an excellent choice for rough environment items.

Why is powdercoating so expensive?

Similar to wet paint, the item to be coated must be cleaned and the surface prepared for coating.  Unlike paint that cures at room temperatures, powder must be heated to approximately 400 degrees F. until the substrate reaches this temperature, then held at this temperature for about 20 minutes for full cure.  For many items, this means the total oven time may be 40 minutes or longer.  Large ovens, whether electric or gas, draw a large amount of energy during this process. Further, commercial ovens are themselves very expensive.  A small gas oven will often cost around $10,000 plus installation. 
           
Powder prices are similar to wet paint costs and since powder doesn’t require any primer/surfacer or solvents, may even be cheaper on a volume basis.  However, the powder application process has a large amount of overspray that is lost in the application process.  Typically, powder is applied to an item in a flow-through booth that filters the overspray through 2 or 3 filter systems before discharging the filtered air back into the shop environment.  Most shops don’t recycle the powder because reclaimation equipment is expensive-more suited for large production runs of the same color-and because virgin powder produces the best finish.

Multicoat processes such as candy colors (a colored translucent coat over a base coat, generally sparkle silver or gold, followed by a clear coat) and striping are more expensive because the item must be partially or fully cured in the oven after each coat, a  process that includes remasking non coated areas.  This makes the cost of the final product 2 or 3 times higher than a single coat process. 

Are there any special uses for powder?

Powder coatings can adhere well to chrome surfaces.  Although not as strong a bond as seen with a roughened surface, the adhesion is much stronger than paint and can work well as an accent area on wheels and covers.

Powder is an excellent primer for paint.  It can be used to create a “metal grind” effect and still give excellent rust protection.  An area of the item to be coated is ground with a grinder to give it a swirl effect, then the entire piece is coated with clear or translucent powder.  Your painter can then apply a custom design encorporating any “metal grind” effect as needed and wet paint the the item.  The “metal grind” area will show through yet be protected by the powder coating.

Are there any special requirements for powdercoating my wire wheels?

Yes.  Wire wheels that are used can be coated if the rim and hub are in good shape.  I do not restore or straighten bent rims or repair cracked hubs.  The same is true for cast wheels.

Used wheels must be relaced with new nipples and spokes.  I use Buchanan’s Spoke and Rim because of their quality and reputation. 

Powdercoated hubs that have sealed bearings (such as Harley hubs since about 2000) must have the bearings removed and NEW ones pressed in once the coating process is complete. The bearing seals may not withstand the high heat used during the curing process.  Removal of these bearings takes a special puller and the removal process pulls the bearing on its inner race – a procedure that is potentially destructive to the bearing.  For most hubs, I can perform this service for you.

Before coating hubs, they must be cleaned.  Brake cleaner is a good product to remove the grease that is inside the hub.  Both used hubs and rims should be grease and dirt free before sending them for coating.  Lightly rusted but otherwise sound rims can be media blasted to remove this surface rust before coating.