galvanising wrought ironwork

[paulmowers]

Hi Guys

I recently built a gate to customers spec, with scrolls and twisted flat bar within the design, all went together well until I collected it from the metal coating company.
As part of the spec it was to be hot dip galvanised, when I collected it there were big blobs of zinc in the interior curves of the scrolls and nasty spikes on the edges of the twists, hours of careful filing restored it to something presentable.
My question is this, with decorative work is this kind of buid up and solidified drips normal or have I picked a crap company to do the work?

This is the first bit of ironwork I have been asked to have galvanised so have no experience of how it should look. Also sorry but can't post any pics as I didn't think to take any.

cheers Paul..

 

[Welderpaul]

Galvanising is classed as an 'industrial finish' and is no way supposed to be decorative. Anything thats architectural metalwork is usually powdercoated after galvanising. The as-dipped galv finish would be 'fettled' before powdercoating - usually by them... so it looks half decent when it comes back.
Plain galv finish is never that nice. At least they didnt bash it off the side of the tank and bend something as happens very regularly with ours.
I think they are all a bit rough imo.

 

[Welderpaul]

Design is quite important when it is to be galvanised. Nooks and crannys should be avoided cos zinc will pool in them and then solidify. It all depends on how they hang them before they go in the tank.

 

[Hitch]

Very normal im arfraid Paul. To a certain extent anyway.
Lumps can be removed with a flap disc/file, or whatever. Just make sure you don't remove too much. If you get sparks, your through the galv. You can tell by the colour aswell, if you have broken the surface. The galv is a whiter colour than the steel.
Its usefull to have a tin of cold galv handy for such instances


Sometimes it comes out better than others, depending on how clean the tank is....we use a couple of comapnies, one is usally better than the other.

 

[paulmowers]

Thanks Hitch and Paul

So by the sounds of it the company is ok as far as they go, but in future I am best to direct the customers toward powder coating, galv paint primer etc.

As you say at least they didn't bend it or lose one of the posts.

Cheers Paul.

 

[Hitch]

A lot of the critical stuff, like stuff for play areas etc, we tend to clean up ourselves prior to powder/paint.

 

[Welderpaul]

Was just gonna say that. Stuff like access ladders, pedestrian guardrails - stuff thats going to be left as galv and in public places, we clean up!

 

[blacksmithstris]

hi,
I had a similar situation with a very ornate gate that I sent off to have galv/powdercoated, which came back in such a state that I cut my hands when unwrapping it. It had blobs and sharp protrusions and just a general poor finish. I got onto the quality control man, who came to see it, and confirmed that it was a shoddy job. The company rectified it at no extra cost. You just have to be fairly direct with the company so they have instructions to finish it properly. That was the first time I had had anything done, so now I speak directly to the workshop manager and ask him very nicely to please give my work special attention. Often, as already posted the end finish is not so important with industrial work, so sometimes it just takes a little reminding of how it needs to appear when finished.

 

[steeo]

I myself have gone off galvanizing altogether and gone down the route of getting stuff metalized and then powercoated.

A new company have started up next to me that do this process and compared to galvanizing it is cheaper, its back to me quicker, the finish is far superior and they are giving me a 30 year guarantee compared to 15 years with galvanizing.

 

[Mikey D]

i recently had some farm stockyard railings galved , basically 48 x3 chs rails with 5mm flats each end , drilled 13mm holes in each end of the rails . they came back with a 2" ' sag ' in them
unbelievable , guess they were hung from the ends and left in the tank during dinner break

i had to bolt them to their posts them use a trolley jack underneath to get them anywhere near straight

cheers mike

 

[Welderpaul]

I sent a piece of 10mm plate, 3m x 2m with a 2m x 1m cut out in the middle to be galvanised. When it came back it was bent corner to corner by 200mm in the middle. Soon had it straightened.

 

[zardoz]

My brother has just had a "box of bits" (nuts and bolts, fastenings, foot brake leaver, clock surrounds etc) off his classic Lambretta Zinc coated. £30 all in and they look great. Is Zinc coating and glalvanizing a different thing ?

 

[^neo^]

Galvanising is a bucket of molten metal which you dunk the job into, and zinc coated is probably electroplated.

 

[Jay]

I know some of the castings you buy can't or rather shouldn't be galv'd. I'm no expert on it but the castings firm that i use says its cause of the amount of air in them when they're cast. Apparantly trying to galv them will make it look like the galv hasd blown off, bit the only time I've ever sent anything with castings on it I always tell the supplier (like FH Brundle) if its an off the shelf casting that I want or the firm that cast them and they will use S.G Iron (I Think) which I'm told is made from melted down rebar scrap.

Zinc coating or Zinc plating is effectively electroplating, the coating is shinier, more consistent but thinner then galv. Some spray shops will also do Hot Zinc spray prior to powder coat, not as much protection as galv but theres no cleaning up-

I did a galv raling run some 60 metres of it that was powder coated that i fitted last week, they cleaned it up great apart from some of the countersunk holes but the chips in the powdercoat had to be touched in with a cellulose aerosol. for my money- galv it, get it back then whack some mordant solution on it and hand paint it- it won't need a primer, and when it gets damaged it recoats or touches in easier- if you've seen it when water and frost gets behind some powder coating you could piuck the lot off!!!