It’s one of Kaser’s golden rules: outdoor parts need to be blasted before being powder coated. It’s non-negotiable for anyone who is at all concerned about the durability of their powder coating against the elements.
But what about indoor parts? If they aren’t exposed to weather, and if durability is less of an issue, do indoor parts really need blasting?
For example, we powder coat a lot of indoor railing that comes to us raw, straight from the fabricator. Most of these fabricators want to skip blasting, because they’re eager to save on costs (both for themselves and for their customers). The railing won’t be exposed to the elements, and the fabricator isn’t too concerned about durability. They want us to pretreat the parts, and then powder coat them.
So what’s the problem?
Raw steel is oily, and often covered in soot. We have spent years perfecting a very thorough and effective pretreatment routine; we’ll even beef up that routine for any un-blasted parts, to get them extra clean before powder coating. Even so, pretreatment is no match against grease that has seeped into raw metal. No matter how clean the part appears after pretreatment, the embedded oil inevitably rises to the surface during the curing process, causing the powder coating to bubble.
It’s not a good look, and it happens a lot.
The simplest solution is to blast the part before pretreating it. That’s the only surefire way to strip the part of all grease, and avoid coating issues down the road. Setting durability aside entirely, it’s an aesthetic issue – we all (Kaser, the fabricator, and the customer) want the part to come out looking good. Right?
Often, it winds up being cheaper – and far more efficient – for us to blast, pretreat, and powder coat a part, rather than to skip blasting, put the part through extra pretreatment, and then redo the powder coating when it bubbles. That’s why we’ll quote railing fabrications the same to blast, pretreat, and powder coat as we would just to pretreat and powder coat. We’re saving ourselves time, and we’re producing a better product. It’s totally worth it to us.
When a non-railing-fabricating customer comes in with an indoor part and requests pretreatment and powder coating, I will often share this with them, too, so that they can make an informed decision. If they tell me that cost is a huge issue, Kaser will pretreat, powder coat, and sometimes the part comes out OK. Sometimes it does.
But the wise have been advised: blasting is about more than just durability.