Open n Shut case. Cast iron painting advice?

[Bm101]

After a bit of advice on painting bare cast iron if possible. I'm (very slowly), building a bench, real life keeps getting in the way though. I've been looking at various alternatives to a handled legvice. Long story short I stumbled (quite literally), across one of all places on a hotel roof I do where they are refitting all the old aircon and ducting. After cursing it for tripping me, a light went on. So I re-homed it.
Gave it the bath of it's life in vinegar and exfoliated with a wire brush several times in the mean time. I've had problems with flash rusting in the past doing this but washing it then slapping on a semi wet paste of bicarb seems to neutralise this issue. (I'm getting round to electrolysis, I'm sure it's a less aggressive method). Anyway, I bought some Hammerite straight to rust spray paint. Thing is, I'm getting an issue similar to gloss paint where it won't take the sharper edges of the wheel. Would I have been better off putting on an base coat and keying it? It was my first reaction to do this based on previous experience but the Hammerite can says no need. Its had 4 coats and it's thickening up slowly but the same areas remain an issue. Edges, round the open/shut lettering. Ive never really used spray paints so I wondered if it was just the thin layers that are causing the issue. Must say I do like the no cleaning brushes though. (lazy B*st*rd)
It's drying in the kitchen much to my Mrs disgust. So i can keep applying coats. Just wondered if gently keying it would help or just keep applying coats.
It's Dark Green btw. Same colour Im gonna paint the Record 52 vice! Just don't tell anyone I love my kneecaps.
For the traditionalists it's as close to British Racing Green as I could find if that makes you feel better. :shock: (sorry :| )

http://imgur.com/a/yvrb2

I tried taking a pic of the painted wheel but the wet paint's just reflecting the light so I gave up and had a cider).
(homer)

Cheers as always
Chris

 

[blackrodd]

Suggest you give Wallace a shout or pm, he's restored some iron in his time and will no doubt save you some work.
Regards Rodders

 

[n0legs]

Zinc phosphate primer is great on cast iron, but a can of U-Pol etch primer from Halfords will do well.
Painting sharp edges is a problem as the paint migrates away from them. Try softening them a bit with some abrasive paper, "breaking the arris" I believe is the term.

 

[Bm101]

Thanks guys. Might see if I can pick up a small tin and touch up with a brush. Think the issue is the spray is so fine. The brush on Hammerite is thicker if memory serves. If I can get an coat or two on the spray might take after a gentle key on the paint. I'll pick up some etcher for the vice while I'm there to save same issues. Thanks again.
Chris

 

[Phil Pascoe]

Yes, a small grindingstone in a battery drill or a dremel will do. Flapwheels on angle grinders are excellent and quick for the accessible parts. No paint will cling well to a sharp corner on anything.

 

[Bm101]

Quick update and one more question.

Nolegs, diolch yn fawr iwan.
U-pol 8 sprayed on the visible faces of the vice. Would you suggest a primer might also be worth using or would this be going backwards/sideways? If I get time tomorrow I'll test a corner with the hammerite to see how it takes. I'd like the paint to be as durable as possible and I have other bits and pieces I can use the paint up on so its not a major issue if I have to pick a can up on the way home.
If it goes well I might cut my losses on the wheel, wait a week for the paint to dry properly and etch that too now I have the paint. While I know the vice is going to get used, the wheel I ain't so sure will work so it's a no brainer to spend much money on it. Probably cheaper to just buy a flywheel tbh. Ah well. I enjoy the little experiments, its all a good learning curve.
So, I'll probably end up the only bloke in the country with a green vice for no reason lmao. Div.

(Oh btw, the lumpy bits where the support rods come through the face of the vice look like that because i faced them in melted wax, to keep the paint off. Never trust masking tape on stuff you can't wrap it round a few times. Always seems to 'leak' especially with oil based paints. No idea if the wax will work it struck me as a getaround today. I'll let you know if it works. Just don't tell the Mrs her scented candle from the front room is wrecked.) :|

Cheers as always!
Chris

 

[n0legs]

Dim problem

A primer coat over the etch won't hurt. I always do, you'll get a better finish.
Plus having a few coats of normal primer allows a little re-sanding without exposing bare metal again, should you need to remove some dust and you will have a good key for the top coat.
I like the wax idea :wink: I can't see it not working, a little heat when the paint is dry and bingo unpainted bars.

 

[Bm101]

Cheers fella. Will do.
Much appreciated.