You gotta love the internet. It only seems like a short time ago that getting information on a subject required pain staking research. Reading books, devouring trade magazine, and speaking to industry experts. Today, a simple web search will pull up pages and pages of information on any subject. Bad thing is – misinformation is also abundant. I wanted to take a moment and try clarify a few things on chemical pretreatment of a part.
We clean for appearance (how does it look), adhesion (how well does it stick), and corrosion protection (how long will it last). A common misstatement by some of the hobby powder experts is that blasting is a sufficient form of pretreatment. While the finish might look acceptable (even though the “orange peel” look will be more pronounced due to surface texture) and the adhesion should be acceptable, there is one vital component missing: corrosion protection. Chemical washing provides a conversion coating which protects from failures from UNDERNEATH the coating. Parts with mechanical prep only will last a small fraction of the time in a salt spray test than a chemically washed part will.
Another way to think about it is by remembering that all metal is porous. When you blast an oily part, where does the oil go? DING -DING- YOU ARE CORRECT – much of it drives INTO the metal. Now we coat the part and put it into the oven and what happens to the oil? It pops out faster than a dancer out of a cake at a bachelor party. Ok, so the humor is sophomoric but the point is that simple logic will show that mechanical pretreatment simply isn’t enough.
That’s all for now. Remember, it’s ok to work for yourself but why work by yourself? That’s what we’re here for. Until the flip side…….
Joey
