I ordered a fence and the provider agreed to deliver it made from hot dip galvanized steel covered with powder painted finishing. The price was significantly bigger thank with the electro galvanization.

They started assembling the whole thing and I have spotted some worrying rust-like stains underneath the construction, on the insides of the C-shape profiles. Please see the pictures.

Am I being scammed? Can you tell, by mere pictures, if it's a hot dip or electro galvanized surface?

Rust ?#1 Rust ?#2 Rust ?#3 Rust ?#4

Please help. It cost a lot but I am afraid the provider is not honest with me.

Update I have used sandpaper to remove the coating from a small part of the element. Here what I saw. Put some salty water on it, we'll see tomorrow. Sandpaper

Also, on the other part of the element used a brush (don't know a type, toiled cleaning type I guess) and here are the effects before and after.

Before some brushing: enter image description here And after: enter image description here

Some of the dark-red dust is gone but yellowish stains remained. Look similar to what I spotted on some scraps from profiles with some holes in them (also, supposedly hot dip coated and powder painted). profile stains

Also spotted some similar constructions in my town and they had technical holes in them (to prevent air bubbles and ex-/imploding of the element while hot dipping) and mine does not have them even almost identical to what I saw. Even more suspicious now...

  • $\begingroup$ You can tell by looking if it was galvanized but you also said it was powder coated on top of that so I'm not sure how you expect us to see through that. But if there's rust does that mean it's on top of the paint? How do you know it's not just dust? $\endgroup$
    – DKNguyen
    Feb 22, 2022 at 15:17
  • $\begingroup$ @DKNguyen thank you for sharing your thoughts. I don't expect you to see through. I thought that maybe there are some characteristic signs of this process like droplets of zinc or something in the corners. The same way you could tell if it was welded, I guess. As for the dust - that's a good point. I will use a brush to try getting rid of those stains and share the photos after that. On the last picture it kinda looks like something sprinkled on top of the surface but on the top-left part of the profile you can see something like a little pitting, like the coating was missing there. $\endgroup$ Feb 22, 2022 at 22:34
  • $\begingroup$ Since zinc does protect uncovered surfaces and a lot is at stake, you could get some scotch brite and rub away a patch on the steel. If you go slow you should see a progression from paint to something else (some kind of galvanization like the typical a speckled pattern or just something different than steel) then steel. $\endgroup$
    – DKNguyen
    Feb 22, 2022 at 22:36
  • $\begingroup$ Sounds like a plan. I'll record the process and share in case anyone's interested. $\endgroup$ Feb 22, 2022 at 22:42
  • $\begingroup$ @DKNguyen, I have updated my post with some pictures. Any thoughts on the matter? $\endgroup$ Feb 23, 2022 at 22:57

1 Answer 1


I don't want to make promises from a photo, but it is difficult to see any evidence of zinc coating. Not electrogalvanized, not hot dipped, possible a poor quality (thin) zinc rich coating ( paint).

  • $\begingroup$ Thank you for your input. Could you elaborate on what evidence there could be of the hot dipping (that's what I'm supposed to be paying for!) process? I'm looking at random pictures of hot dipped profiles and can't see anything obvious. If I took a sample and damage it somehow can we tell then? Like if I ground it a bit with the sand-paper or something? I bet I can find some leftovers to experiment on. $\endgroup$ Feb 22, 2022 at 22:39
  • $\begingroup$ Hot dip is usually glossy and has "spangle" pattern, probably you can find spangle pattern on the net. And I expect a galvanizing failure ( loss of zinc) to appear as discrete spots ,not a general blush of rust. $\endgroup$ Feb 23, 2022 at 0:56

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