| Gallery, Projects and General > How do I?? |
| How to paint cast iron? |
| (1/5) > >> |
| PekkaNF:
I have a crappy pilar drill that might evolve to a different drill or threading stand. I have practiced rust removal. I think I have it covered. But how to prime and paint them? Bearing in mind that we are talking about old uncomfortable piece of cast iron that has just it's paint removed with drain opener and then dunked in vinegar, citric acid, or phosporous acid to remove rust. Smaller parts are blasted with soda. Now the interested part: When and how to remove oil/grease? And How? Old tools are doused with oil and such. I have used car cleaning shampoos and solvent wash. I also have silicon remover. It removes grease, but is really expensive for it. I bought small steam cleaner. Steam and detergents seem to work. I see epoxy being used and recommended for basecoat. Followed by automotive 2 part acryllic paint. I have nothing against 2 part paints or spraying and very tempted to go this way. BUT I imagine it could be a pain to remove if screw up well. Suggestions about going 2 part spray paint route? I just want practical surface with minimum fuss, nothing like display quality just clean, practical and easy. Pekka |
| DavidA:
Pekka, Use acetone. Or maybe IPA (Iso Propan Alcohol) both are good for removing grease. I would suggest tricholoethelyne, but it is banned as a solvent here unless you capture the vapor. I don't know if you are aware that a good way to dry parts after washing in water is to rinse them with IPA. It takes up the moisture. Dave. |
| Fergus OMore:
Arguably the best or certainly one of the best methods is to follow Prof. Dennis Chaddocks book on the Quorn. If the drill stand and whatever is heavily oil damaged, the only sensible way is to remove ALL the old filler/paint and whatever. to come down to bare cast iron and start again. When I did my lathe bed, I used a jet wash and detergents to get most of the oil/grease and rubbish off. At least it is possible for the dog to see the rabbit. If you have a metal receptacle big enough, I would have a caustic soda boil. This is how the paint, plastics and varnish factories get rid of the burnt on residues. What you are actually doing is making a crude cheap soap cum paint stripper. You could put your mother in law in as well- if the fancy takes you. You now have a situation with a clean set of castings and no mother in law. You now have to phosphate with a pre-clean which is probably nothing more than phosphoric acid and hydrochloric( muriatic acid) which might have a fancy name. It needs to be washed off and dried thoroughly before filling. I tend to use a concoction of fibreglass resin and a decent filler. Most good car body people will sell you their brand. Use what the trade uses! With the filler set hard, it is time to progressively rub down until the whole thing is just beginning to show the high spots of cast iron. You need finer and finer grades to get there. Obviously thee will be holes and low spots and the quickest way to find them is to spray a mist coat over a primer. It is easier with a contrasting one because it needs rubbing off. It will leave a few low spots to be filled. This time use a cellulose putty and after rubbing down again should start showing 'truth' with no high or low spots and ready for a proper number of primers rubbing down every 2nd coat. Finally, it is time to put on the gloss, again rubbing down every 2nd coat. When you re satisfied- Throw the cat out and do two coats -one wet over wet and --run away. Actually, I've just done a scratch on the front wing of my Audi A4 Avant S Class and am ready for the clear over base because it is silver. You'll enjoy - I think Norman |
| Pete W.:
Hi there, all, I second much of what Fergus has written. When I bought my drilling machine, it was caked with thick grease reinforced with fine brass swarf. I scraped off as much as I could with a variety of instruments (wooden spatula and iced lolly sticks) and then soaked the castings in hot caustic soda solution. Followed up with several good warm water rinses and dried by brushing with methylated spirit. That got me back to a paintable surface. This was back in the early 1970s and I don't remember what I used for a primer but my top-coat of choice in those days was Valspar 3-hour enamel. Or was it 4-hour? It doesn't matter because they subsequently changed the recipe and then I think it disappeared from the market. I believe the original Valspar was alkyd resin based. I was told that the traction engine restoration folks would dilute Valspar 50/50 with genuine turpentine and then flow it on with a sign-writer's mop (that's actually a soft brush). It would self-level and then dry to dust-free in seconds! I guess you'd have needed several coats. Another thought - there's a place in Portsmouth called 'the strip joint', they dip old doors or furniture in a stripping solution that removes the paint. (It also removes the filler and the glue!!!) The process is preferable to sanding off the old paint, especially if it's old enough to be lead-based. I guess there are similar emporia in most big UK towns & cities. If you have them in Sweden Finland, maybe one of them would take on your castings??? Edit: I'm sorry, I got your country wrong. I hope I haven't caused an International Incident!! :bow: :bow: :bow: |
| PekkaNF:
--- Quote from: DavidA on August 08, 2014, 03:08:31 PM --- Pekka, Use acetone. Or maybe IPA (Iso Propan Alcohol) both are good for removing grease. I would suggest tricholoethelyne, but it is banned as a solvent here unless you capture the vapor. I don't know if you are aware that a good way to dry parts after washing in water is to rinse them with IPA. It takes up the moisture. Dave. --- End quote --- Thanks. That is a good one. I have acetone and IPA (not very clean/industrial/has some water). Why I didn't come to think of alcohols, they soak up water. One day I used electric leaf blower to dry car underparts prior to rust protection paint. Noisy but pushes loose water away from all crevises. Does cast iron really needs filler? Most (cheap) car body fillers are not epoxy, but polyester filler and that is incompatible with most of the acid base paints and some other chemicals. Not too keen on them. Pekka |
| Navigation |
| Message Index |
| Next page |