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Writing a finishing specification for powder coating
After careful analysis of the facts, performance and technical capability, we’ve chosen a performance powder coating. We’re using superior performance 100% FEVE Fluoropolymer powders on our exterior applications.
But does our spec wording match up?
This is a question asked of us recently. So often the correct language for performance powder is either not even part of the finishing spec, or has simply been copied over from the liquid language. When this is the case, important information like number of coats (fewer with powder while still achieving the same performance levels) and percentage of resin (100% FEVE Fluoropolymer resin) are not changed.
So what are the two simple things to watch out for?
1. Number of Coats
On aluminum, performance powder is usually a single coat application. That includes high performance FEVE Fluoropolymers like IFS 500FP. And yes, that is the same for metallic or mica finishes.
Why so? Well liquid PVDF requires a primer for two reasons. Firstly, it doesn’t have naturally good adhesion, so the primer help with this; the primer sticks to the substrate, top coat sticks to the primer and they work together to deliver the good adhesion we want.
With FEVE Fluoropolymer powder, there is no adhesion issue due to the way powder is made. All of the raw materials – including everything needed for excellent adhesion – are put into the extruder and controlled heat and pressure are used to completely homogeonize the mix. This means when the mix comes out of the extruder and is ground down to powder, it has excellent adhesion built in.
The second reason is the PVDF actually allows a little UV light through the surface of the coating, so the primer helps protect the substrate from UV degradation. FEVE Fluoropolymer powders do not allow UV through the surface of the coating – so the top coat is doing its job protecting from UV degradation. A primer is not needed to do that – because that’s what the top coat is doing!
So what about clear coats on metallics/mica powders? That’s what PVDF needs so it must be needed on everything right? In a word, no.
We use what is called encapsulated mica – the mica is encapsulated in hard working resin to protect it, and then it is bonded into the powder, which is loaded with resin. And as we all know it’s the resin that does the hard work!
With that in mind, most of the time on aluminum, a single coat FEVE Fluoropolymer will give you the same or better levels of performance, warranties and colors, with an improved sustainability footprint. We say most of the time, because on occasion (like a recent project right on the beach in Hawaii) the decision was taken to add another level of protection due to the extremely harsh weathering conditions and location. Fortunately most applications aren’t on the beach in Hawaii!
Superior Performance Organic FEVE Fluoropolymer Powder Finish: Single-coat Fluoropolymer Powder finish complying with AAMA 2605 and containing 100 percent fluorinated ethylene vinyl ether (FEVE) resin. Prepare, pretreat, and apply coating to exposed metal surfaces to comply with coating and resin manufacturers' written instructions.
Color and Gloss: [As indicated by manufacturer's designations] [Match Architect's sample] [As selected by Architect from manufacturer's full range] <Insert color and gloss>.
- Product code:
- Color:
- Manufacturer:
- Contact:
When it comes to high performance powders on steel, because the pretreatment options aren’t as good, we would recommend a powder primer first. With certain types of steel corrosion can be a concern, then we would recommend a zinc rich powder primer, followed by the top coat.
So the wording might look something like this:
Superior Performance Organic FEVE Fluoropolymer Powder Finish: Two-coat powder coating system, including zinc rich powder primer followed by a Fluoropolymer powder complying with AAMA 2605 and containing 100 percent fluorinated ethylene vinyl ether (FEVE) resin. Prepare, pretreat, and apply coating to exposed metal surfaces to comply with coating and resin manufacturers' written instructions.
We often get calls from General Contractors asking for 3 coat powder systems (they don’t exist) or asking for an incorrect product because the spec wording is liquid vocabulary rather than powder.
Please make sure you revisit the numbers of coats required in the finishing section and ensure it is correct for the product you choose. So, when you see phrases like “3-coat system” you should hear an alarm in your head – that language is not going to work for powder!
2. Resin Percentage
100% Fluoropolymer - what's the deal?
Most good finishing specs citing liquid PVDF exterior finishes call out for a minimum of 70% PVDF Fluoropolymer resin in the liquid coating. That should change when specifying high performance powder coating.
Instead of 70% Fluoropolymer resin, the spec should demand 100% FEVE Fluoropolymer resin.
We know everyone’s specification requirements are different, so we are here to help. Make sure your spec wording is correct, make sure that your coatings manufacturer is available to any GC to help with product order and delivery, and make sure that what you took the time to specify is actually applied to the substrate.
There are simple specification wordings, for each type of architectural powder, available to download at IFS.com, but if this style doesn’t work for you contact us for help with tweaking your spec to make sure it’s correct no matter what coating type