I moved into a previously owned house that has many decorative wrought iron items, including a swinging entry gate. As expected, many have rust.
Given the numerous "nooks and crannies", how does one prepare those surfaces for spray painting. Sanding and steel wool will be an improvement, but I am sure rust will remain. Is there a coating, to be applied on the rusted surfaces?
Most appreciative, for any guidance!
Hammerite claims to be ok direct onto stable rust.
Wire brushing to remove the really loose rust, followed by Jenolite and then by Hammerite. Jenolite is a strong solution of phosphoric acid that comes as either a liquid or a jelly. Follow the instructions. It forms an impermeable coating of iron phosphate when applied to rust. Basically, the rust goes black and glossy. Hammerite is...well...Hammerite!
Does normal hammerite claim that? They do sell a specific "direct to rust" version.
Otherwise apply a rust eater to convert/stabilise the rust before painting ...
80% Phosphoric Acid is also available on Ebay for around £10/litre. Liquid form has the consistency of water. I've just wire brushed, painted on the acid and then left for 24 hours before over-painting
POR15.
Evil stuff to work with (don't get it on you), but given that it stands for "paint over rust", it seems to work well.
HCl also works. Both require protection against touch if left unattended. R inse thoroughly, and watch as it dries & rerusts. DAMHIKT.
Hammerite is overpriced gloss paint, and there's no such thing as stable ru st.
NT
I have my doubts that anything is completely going to cure this. I had a gate etched and then repainted with hammerite some years ago, but the rust did come back in the same old nooks and crannies. I tell people its the 'rustic' look...:-)
Brian
If you can remove the items, take them to a local galvaniser they will acid dip them a galvanising should keep the rust at bay?
Richard
Iron phosphate is both stable, and provides a very good base for paint.
It is not however, galvanising. Or zinc passivating:
"Ferrous materials, including steel, may be somewhat protected by promoting oxidation ("rust") and then converting the oxidation to a metalophosphate by using phosphoric acid and further protected by surface coating. *As the uncoated surface is water-soluble*, a preferred method is to form manganese or zinc compounds by a process commonly known as Parkerizing or phosphate conversion. Older, less-effective but chemically-similar electrochemical conversion coatings included black oxidizing, historically known as bluing or browning. Ordinary steel forms a passivating layer in alkali environments, as reinforcing bar does in concrete."
And there you have it. The phosphated surface is stable, and can be painted, but if the paint later fails, the phosphate will wash out and corrosion start again.
Only three finishes have I seen withstand corrosion in outside conditions, and they are zinc galvanising, and zinc, or cadmium passivating.
But phosphated iron and paint is a very good alternative, if done carefully.
The best option would be to grit blast back to bare metal and apply an epoxy based paint system.
..after galvanising or passivating...
Strangely there's lots of "apply direct onto rust" paints and varnishes available in France. One that you may find in the UK is Owatrol.
I have used a similar produce "Vernis pour Rouille" successfully both on our boat in France and on some outdoor bare steel here in the UK.
Hammerite is an expensive con. Doesn't last any longer direct to wrought iron than an ordinary oil based gloss paint.
Might do - but any paint will flake off much sooner.
I am assuming that most of it cannot easily be removed, or I would have recommended powder coating.
If the OP's objects are Wrought Iron then you would not be able to galvanise them by dipping, but somehow the term Wrought Iron has become to mean mild steel bent into fancy shapes and welded or even pop riveted together. Somehow this has managed not to become a concern of trading standards.
G.Harman
By painting phosphoric acid on you create a phosphate that's not well adhered, and you say water soluble. That's what your paint goes on to.
I don't know how many diyer paints are actually not vapour permeable, I doubt household gloss would qualify.
NT
snip
-Er, no! Present day Hammerite is not the same as the old stuff. I sometimes see old tins of original Hammerite on market stalls (often with foreign labels). This would be a better bet that the modern stuff, but I haven't been able to find any of the old-type thinners for it. Contrary to the instructions I found it better to thin the first coat so it would go into the nooks and crannies and then follow up shortly after with an undiluted coat.
No, Its VERY well adhered. That is the whole point of phosphating.
and you say water soluble. That's what your paint goes on
Most oil based exterior paints are watertight.
That's why we paint things.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.