Rust Bloom on Water Based Paint over Zinc Primer

[eSCHEn]

I've made an outdoor swing for the wife out of mild steel. I primed up using zinc primer and coated in water based garden paint of a colour she chose. However, the day after the paint was applied there is substantial rust bloom and I'm going to have to redo the whole damn thing again

Could SWK explain to me what I'm doing wrong here? I'm following the instructions but getting dreadful results.

Here's the primer. It's a brand owned by plastikote, who I've had good results before with:


I sprayed a coat and allowed to dry thoroughly. About three days. Here's the result with the primer on:


I then did a coat of this paint followed by another about four hours later (both brushed), which is the recommended re-coat time:


Here's the result just now:


I have used this primer before as I thought it a general purpose zinc paint based on the picture of palisade fencing on the front of the can. I was wrong. It rusted badly outdoors. After the rust that came I figured it must be a porous primer and need a top coat. Here's what the zinc primer turned out like about a month after painting and outdoor storage:


Am I doing it correctly? If I am is this just a case of **** paint?

To try and answer some questions I know will be coming:

• Metal is mild steel.
• Was taken back to clean, bright bare metal with a poly disc.
• Cleaned with a quick wipe with a paper towel moistened with gunwash and allowed to dry off then given a wipe over with a dry paper towel.
  
• Primer immediately applied after cleaning.
  
• Zero rust was apparent before and after priming.

Recommendations for a good bare metal primer than comes in a rattle can would be gratefully received. Obviously I need to be able to overcoat in the above mentioned water based paint.

Pretty gutted with the result if I'm honest. I don't enjoy painting and the thought of having to do it all again is soul destroying. Almost thinking of finding a powder coater and getting a price.

 

[richie00boy]

I sprayed a coat and allowed to dry thoroughly. About three days.

There's your first mistake, 1 coat of an aerosol is simply nowhere near enough.

Cleaned with a quick wipe with a paper towel moistened with gunwash and allowed to dry off then given a wipe over with a dry paper towel.

And there's your second and third mistake mistakes. Thinners/gunwash is not really much good for cleaning prior to painting, use panel wipe. And you must wipe off the cleaning solution not leave it to dry, otherwise the contaminents just sit there.

I then did a coat of this paint followed by another about four hours later (both brushed), which is the recommended re-coat time.

Another mistake there. Those kinds of paints are for wood really and have no corrosion inhibitors.

Recommendations for a good bare metal primer than comes in a rattle can would be gratefully received. Obviously I need to be able to overcoat in the above mentioned water based paint.

Zinc spray and primer are different things. Really you should use an etching primer over zinc spray as zinc is difficult to adhere to. That said, the zinc content in that aerosol is so low (judging by your photo of the "primed" article) that it must contain paint pigment too so is probably ok to paint over as a primer.

Can you get hold of a cheap electric sprayer? You could spray some Lechler epoxy with that and then you would be fine to put your daft paint over it. Limiting yourself to aerosols you are going to need a few to get the film build.

 

[eSCHEn]

Don't hold back Ritchie

In all seriousness though, thank you very much for the detailed reply. I'm not good at this kind of painting and your advice is very helpful

Okay so I think I can just bin this remaining rattle can as it sounds like this stuff is not very good.

The Ronseal stuff is marketed as bring suitable for suitably primed metal but yes, I take your point: I've used similar paint in the past but only on rough sawn wood.

I have a small 2HP compressor and a couple of guns. I've not used them as one came free with the kit I bought for it's air blower and the other I inherited from a job lot of tools I bought. Here they are:


I don't have anywhere to spray but outside and as I live on the coast it's permanently windy so it's not easy.

I did look at the lechler epoxy but it all seemed to be 2K and I don't wanna start with that stuff as it sounds nasty. I've no BA or air fed masks.

The silly paint is SWMBO's choice as she wants a colour she likes (of course).

I think I might just get a quote from my local steel merchant for coloured galv / powder. They do a drop off service and chances are that it's going to cost close to what I'm going to be paying for proper primer, paint and panel wipe.

Still absolutely gutted though. The shape of this makes it a pig to prep and now I have to do it all over again

Thanks again for the advice.

 

[richie00boy]

Epoxy is 2 component, but does not contain isocyanates so you can use a suitable mask. You could actually brush it on, I only thought spraying because you mentioned wanting an aerosol primer.

 

[I'm getting on a bit]

Hammerite

Can go over rust no prep but best to

Rattle cans and smooth finish

Colours limited though

 

[eSCHEn]

Cheers IGOAB, the wife looked at hammerite but didn't find the colour she wanted.

My suggestion of red lead for everything did not go down well lol.

 

[the snooper]

I would use epoxy primer, and I certainly wouldn't use a water based paint on something that will be out in all weathers, you need something uv stable, you should be able to get the colour of your choice mixed up at any automotive paint suppliers

 

[eSCHEn]

Epoxy is 2 component, but does not contain isocyanates so you can use a suitable mask. You could actually brush it on, I only thought spraying because you mentioned wanting an aerosol primer.

I like rattle cans as they're really convenient, that's why. Not fixed on spray or brush really but like I say, I'm not really geared up for spraying.

I would use epoxy primer, and I certainly wouldn't use a water based paint on something that will be out in all weathers, you need something uv stable, you should be able to get the colour of your choice mixed up at any automotive paint suppliers

Yeah I think I'm gonna just see what the damage is for someone else to powder coat it. By time I get all the bits purchased and my time allotted it'll be much easier.

 

[cumbriasteve]

I have not had much success with water based paints, rust appeared within hours on one item and the other was still wet 3 days later.

I know that's no help but just felt like having a twine.

re the Hammerite, would never use it, overated rubbish in my opinion, the recoat time is too critical to ensure bonding to the original coat, too easy to end up with layer sitting onto layer and not combined into it.

 

[eSCHEn]

I have not had much success with water based paints, rust appeared within hours on one item and the other was still wet 3 days later.

I know that's no help but just felt like having a twine.

re the Hammerite, would never use it, overated rubbish in my opinion, the recoat time is too critical to ensure bonding to the original coat, too easy to end up with layer sitting onto layer and not combined into it.

Doesn't need to help Steve, it's just nice to know I'm not the only one who hasn't had luck with this sort of thing.

I had heard hammerite was a bit poor these days but was going to chance it if I could get the colour she wanted. Glad I couldn't get it now as I'd just be removing that crap to put this rubbish on!

Clean and prep tonight and I'll see what the damage is going to be at my local place. What state do you normally take items to be powder coated, bare metal?

 

[cumbriasteve]

What state do you normally take items to be powder coated, bare metal?

No idea mate but tend to think as clean and free from any other surface material as possible.

At least you have a powder coater, nothing down this way, wish there was.

 

[eSCHEn]

Amazingly for here there's actually two to choose from. One seems to do it in house and the other sends it out away up the country to be done.

Hoping it won't be too ****-stingingly expensive.

 

[eSCHEn]

What state do you normally take items to be powder coated, bare metal?

No idea mate but tend to think as clean and free from any other surface material as possible.

At least you have a powder coater, nothing down this way, wish there was.

Actually Steve I think you might have one. Franklin Steel are one of the ones I'm looking at and I just noticed they have a depot in Whitehaven, here's the relevant page. Don't know if it's any use to you?

 

[cumbriasteve]

Tried them mate, told me they did not do it anymore, I got an impression I was being fobbed off but get my steel from them so know them and always been ok in the past.

 

[eSCHEn]

Tried them mate, told me they did not do it anymore, I got an impression I was being fobbed off but get my steel from them so know them and always been ok in the past.

Ack that's a bugger. Thought I'd spotted something useful there!

 

[marlinspike]

Aldi do a straight to metal paint that is good. Comes in black, cream, and a couple of other colours. Screwfix do a cheap 'No Nonsense', ie. own brand, zinc spray too if you want to save a bit on primer.

 

[MattF]

I have not had much success with water based paints, rust appeared within hours on one item and the other was still wet 3 days later.

Pretty much the same opinion here. Water based paints are one of those things which no matter how many times I see people using them, hear their praises sung etc., I can still never figure out why. I've either just come across a shockingly poor selection personally else water based paints are just complete and utter crap, IMHO, even when aimed at wood use.

re the Hammerite, would never use it, overated rubbish in my opinion, the recoat time is too critical to ensure bonding to the original coat, too easy to end up with layer sitting onto layer and not combined into it.

Plus there's its ability to drag the previous coat off if you're outside of its recoating window.

 

[SmartWerks]

What state do you normally take items to be powder coated, bare metal?

No idea mate but tend to think as clean and free from any other surface material as possible.

At least you have a powder coater, nothing down this way, wish there was.

Powder coaters recently opened in Ulverston

 

[eSCHEn]

Pretty much the same opinion here. Water based paints are one of those things which no matter how many times I see people using them, hear their praises sung etc., I can still never figure out why. I've either just come across a shockingly poor selection personally else water based paints are just complete and utter crap, IMHO, even when aimed at wood use.

Other than on rough sawn wood I totally agree Matt. Absolute poop.

 

[zx9]

This is real Zinc primer http://www.fosroc.com/product/show/galvafroid , we use it for coating the cut ends of Unistrut, you can tell it has a lot of solids (zinc) in it the tins are unbelievably heavy.