Clear Coat Over Galvanized Tube
Heidtman adds clear coat to galvanized tube. Every galvanized size leaves our mill clear coated as standard, or with a conductive clear coat that meets UL 2703 for solar racking, cured in line by ultraviolet light.
A Clear Layer Over the Zinc.
Galvanized tube is made from zinc-coated coil, and the weld seam is coated again in line. The clear coat goes on last, over the whole outside of the tube, before it is cut to length.
Thin and Even
The clear coat is 0.5 to 0.8 mil dry and the conductive clear coat 0.3 to 0.5 mil, a fraction of the thickness of a sheet of paper. Neither changes the tube's outside size.
Cured by Light
UV lamps cure the coat in a moment as the tube moves down the line. Nothing has to dry, so the tube can be bundled straight off the mill.
No Solvents
Both coats are free of volatile organic compounds and hazardous air pollutants. Nothing evaporates from them in our plant or yours.
Clear or Conductive Clear.
Clear coat is standard on every galvanized size, and conductive clear coat is offered on every size too. They protect the surface the same way; the difference is whether electricity passes through the coat.
Clear Coat
A clear seal over the zinc for tube that is stored, shipped and handled before it is built into anything. It keeps the zinc bright and helps against the white rust that forms in tight, damp bundles.
- Dry thickness
- 0.5 to 0.8 mil
- Solvent resistance
- Over 50 MEK rubs
Conductive Clear Coat
The same protection in a coat that conducts electricity, so parts can be bonded and grounded through it without scraping the coat away first. It meets UL 2703, the bonding and grounding standard for solar racking.
- Dry thickness
- 0.3 to 0.5 mil
- Solvent resistance
- Over 100 MEK rubs
Which to Order
Order conductive clear coat when your parts have to carry a ground or bond through the tube, as racking and electrical structures often do. Otherwise the standard clear coat is the right choice. Say which on the quote.
What It Does for the Tube.
Zinc protects steel by corroding first. The clear coat protects the zinc's surface where it is most exposed: in tight bundles, on the truck and in the yard before the tube is built into anything.
Helps Against White Rust
Water trapped between lengths in a bundle turns bare zinc into a white, powdery oxide. A sealed surface keeps more of that moisture off the zinc, so tube stays bright longer in storage.
Bends and Forms
The coat stays flexible after months outdoors and passes a bend test around a 3/8 inch mandrel without cracking, so it moves with the tube when it is bent, swaged or punched.
Hard and Well Bonded
It holds to the zinc with the top adhesion rating and an H pencil hardness, so it stands up to the scuffs of handling, banding and loading.
Welding and Painting It.
Clear-coated tube is worked the same way as any galvanized tube. The coat is too thin to change your weld settings or your bending dies.
Welding
The coat burns off at the weld along with the zinc. Weld with the ventilation you use for galvanized, and touch up the weld with zinc-rich paint.
Painting and Powder Coat
Clean the tube and run an adhesion test on a sample before a production run. Your coater can tell you whether to scuff, pretreat or coat straight over it.
Storage
Store bundles dry, off the ground and with air around them. The coat helps against white rust; it does not make a wet, tight bundle safe for months.
Questions.
Have a coating or finishing question we have not answered here? Ask us; we can send samples.
What is clear-coated galvanized tube?
Galvanized tube with a thin, clear coat over the zinc on the outside. The coat is applied and cured by ultraviolet light on the mill, so it is part of the tube when it ships.
Which galvanized sizes can be clear coated?
All of them. Clear coat is standard on every galvanized size, and any size can be ordered with conductive clear coat instead; say which on your quote.
Can I order galvanized tube without clear coat?
Yes, on request. Without it, the zinc has less protection against white rust in storage, and our claims policy treats white rust on that tube differently; ask for the terms with your quote.
What is conductive clear coat?
A clear coat that conducts electricity. It protects the zinc like the standard clear coat, but parts can still be bonded and grounded through it. It meets UL 2703, the bonding and grounding standard for solar mounting systems.
Does clear coat stop white rust?
It helps. White rust forms when water sits on bare zinc in a tight bundle, and the clear coat keeps more of that water off the zinc. Bundles should still be stored dry and ventilated.
Is clear-coated galvanized the same as hot-dip galvanized?
No. Our tube is made from zinc-coated coil, with the weld seam coated again in line and the clear coat on top. Hot-dip galvanizing dips the finished part in molten zinc, which leaves a thicker coat inside and out.
Can I bend clear-coated tube?
Yes. The coat stays flexible after months outdoors and passes a bend test around a 3/8 inch mandrel without cracking.
Can I weld clear-coated tube?
Yes, as you would any galvanized tube. The coat burns off at the weld with the zinc; touch up the weld afterward with zinc-rich paint.
Can I paint or powder coat over it?
Usually, but test first. Clean a sample, coat it and run an adhesion test before a production run, since pretreatments differ from shop to shop.
Technical Data.
Coating test results.
Test Results.
From each coating's technical data sheet, at the standard formulation. Ask us for the data sheets with your quote.
| Property | Clearcoat | Conductiveclear coat | Test |
|---|---|---|---|
| Dry thickness | 0.5 to 0.8 mil | 0.3 to 0.5 mil | – |
| Adhesion | 5B, the top rating | 5B, the top rating | ASTM D3359 |
| Pencil hardness | H | H | ASTM D3363 |
| Flexibility | Passes a 3/8 in bend | Passes a 3/8 in bend, no cracking | ASTM F1683 |
| MEK double rubs | Over 50 | Over 100 | ASTM D1308 |
| Acetone double rubs | Over 40 | Over 100 | ASTM D1308 |
| VOC and HAP | 0% | 0% | – |
| Conducts electricity | No | Yes | – |
| Cure | Ultraviolet, in line | Ultraviolet, in line | – |
The coat protects the surface. It adds to the zinc's protection; it does not replace it, and storage conditions still matter.
Ask for Galvanized With Clear Coat.
Tell us the size, wall and footage, and whether you need clear or conductive clear. The quote form takes about two minutes.