How to paint cast iron?

[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!!            

[PekkaNF]

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.

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

[vtsteam]

Just wanted to add one off beat factoid about removing grease and even baked on stuff.

Fast Orange. I've been amazed at what it will do.

We were given a free ten burner commercial range -- a 1957 two oven Garland. It was, as you can imagine buried under layers of cooked on grease/varnish, 1/4" deep in places.

I thought the chrome had rusted off of the gas taps because just a few flakes of chrome were left.

Wrong. I happened to have no cleanser available after I moved it through an open wall (I was just building the house) and no running water, or hot water for that matter. But I had a bottle of Fast Orange. So at lunch, I thought I'd clean the taps, and do a little something on the range every day.

I wiped on the Fast Orange and let it sit 5 minutes, then wiped it off with cold water and a paper towel. Brilliant chrome all of a sudden, in perfect condition. What I thought was rust was baked on grease varnish. I have learned since that this stuff will take off just about any grease/oil/farnish, and even wet oil paint form hands.

It's not just a hand cleaner, anymore.

[PekkaNF]

Exelent! And I can get that Fast orange here (Finland) too. Finally something good about globalisation!

Yesterday I disassembled partly the drill head to use some parts of it. Looks like the moving spindle assembly/body fit is exccelent. Maybe I should try to fix the spindle bearings and that. Really funny english contraption. Some parts are really nicely done and some have shortcuts.

Now, the dilemma: The spindle head has some good fits and I don't want to destroy them. Plan:
1) Grease/gunk removal, I'm going to try fast orange.
2) Rust removal: Fast application of citric/phosphorous acid mix.
3) Wash with metal wash detergent
4) water removal - I'll try IPA

I'm putting here some pictures.

Allication of drain cleaner (PH10 or something caustic soda)

Then I dunked them in mild citric/phosphorous acid mix for overnight.
Pekka

[vtsteam]

Of course, for most machinery work, you would want the non-pumice variety of Fast Orange -- obviously pumice isn't anything you want on bearing surfaces, Though I have used it on external cast iron surfaces where the whole part would be later hosed off..

[awemawson]

It's brilliant stuff with the pumice for hands. I first found it at a welding course I attended some years ago and was amazed how it shifts grime - far better than Swarfega etc. I now buy bulk packs of the stuff on ebay when the price is right.

[PekkaNF]

I think that the pumice nowadays is plastic particles. Least on some I have seen.

[PekkaNF]

Some more progress.

Spindle is shot. Bearings are pretty loose and some parts have clearance.

Drill chuck is Kawasaki! It looks like it is beyond repair, but I'm tagging it along and see if bring myself to disassemble it.

Pekka

[PekkaNF]

There is one thing I wonder:
This three step pulley has two bearings. They seem to be grease lubricated and shielded. However on top the pulley there are two conical holes with stamped "Oil" in them. Is this just case of using old stock pulley after product design? Someone might have changed the bearings.

The spline shaft looks very nice, but awfully skinny for my purpose. I was surprised to find that splined hub was made of plastic that appears to be nylon, judging from the looks of it.

Not sure if the pulley assembly will disassemble civilized manner.

Pekka

[chipenter]

You have come to the same conclusion as me , I just have a head but it's in good condition and the chuck cleaned up like new , now idea what to do with it .

[PekkaNF]

You have come to the same conclusion as me , I just have a head but it's in good condition and the chuck cleaned up like new , now idea what to do with it .

Jeff, yours looks very much same than mine. This looks like pretty good for drills up to 10 mm. The bottom bearing looks like a very standard deep groove ball bearing. It's only a single small bearing and can't take huge amount of axial load. Original circlip had faild on bottom and had been bodged on mine.

I'm not sure yet what to with mine. I'm between rebuilding/improving it littel or making it a tapping stand for this:

[Fergus OMore]

It is quite interesting to know a way to  do these things but it hardly cost efffective. My car repair saved a loss of noclaims bonus and my excess on my insurance cover is more than my cost of raw materials is less than having a whole new drilling  machine. I had a quite uprated staking and rivetting tool which I made to improve on the earlier one which was made from three small car conrods. I had the castings and  all the bits to do the headstock but the motor was a bit more than a complete new drilling machine which was only about £30 with a small vice. No holding down bolts- but who cares?

Whatever turns you on?

Cheers
Norman

[PekkaNF]

Hobbies are normally not that cost effective or they were business. I'll do many things just to learn. Sometimes I learn more sometimes it just for amusement (or disappointment).

I got Alkyd top coat that is intended for industrial machines. It's one pack system, only thing I don't like that its thinner uses xylene.

But now this project comes to halt. Work and car/commuting problems will keep me busy, least this week.

Pekka

[awemawson]

I'd be interested to hear your issues with xylene Pekka.

I've been spraying quite a bit of xylene thinned paint recently - did you see those blue spars on the tractor flail?

Is it a performance issue or a heath issue?

[Pete W.]

Hi there, Pekka and Andrew,

Xylene is used a lot in microscopy (one of my other vices!).  It's used to remove congealed immersion oil from objectives and some microscope manufacturers recommend it for cleaning the complete microscope stand.  Others do not, e.g. Vickers Instruments recommended alcohol.  It was recommended to me for dissolving old grease from a microscope focussing mechanism.
A common problem with older microscope stands (the only type I can afford!       ) is that the grease goes really really hard and forcing the focus knobs can cause damage!          

I haven't acquired the H&S sheet for xylene but it's unpleasant stuff.  I wouldn't either store or use it indoors.  Good ventilation is IMHO highly necessary.

I bought a litre from an eBay seller who claimed to use 'European Union Approved packaging - it arrived in a standard polythene bottle with a twist of kitchen roll around the screw cap!  I kept it in the small shed but by the time I got round to using it, most of it had disappeared! 

[awemawson]

Got mine in 5 litre cans - two of them !

[PekkaNF]

Oh, it's just that the paint distributors here make a point when solvents are way more nasty than "industry standard". It's it really very complicated to avoid all exposure and risks, therefore I try to use ppe that is good enough and avoid exposure (paint outside, use respirator etc.).

I don't think it's really that harmfull when proper precaution is observed. But still, I would not bring it inside house.

I have 2,7 litres of paint, and 3 litres of solvent (smallest cans). Now, I need to find out what would be right container to store thinned and ready-to-paint mixture (usually tehnd to mix a little more than needed) and I don't like pouring any of that back into the original can.

Pekka

[PekkaNF]

Bit more preparation and paint removal. It has been raining here and mys "shop" is outside with these dirty works.

I tried fast orange and it does removes grease, gunk, dirt really nice when assisted with a nylon brush. It does not seem to remove the paint I have on cast iron though. I have one sticker removal spray that has citric oils etc. and it does good job removing sticky glue.

I found out that unheated liquid drain opener right from can is a lousy pain remover. It does something but not very fast and if you let it soak for hours you exchange paint for rust.

First two pics on this experiment.


Then again when I used four litres of 70C water, laced with 0,3 litres of granulated drain opener (caustic soda?) and applied it to preheated chunk of cast iron and paint was removed in 15 minutes excluding few corners and spots. I applied some steam and that too was cleaned fast.

last two pictures on this episode

I'm very sure that drain opener/caustic soda/alcaline would be a really bad idea on aluminum, thin it would bad also copper metals?

Grit blasting would have worked really nice on these I had the means.

Pekka

[PekkaNF]

A little update. I wonder if anybody reads this, because this is pretty basic.

Anyways, I washed the stuff, Dunked them into heated mild phosphoric acid and dried with hot air blower.

Then I taped and masked the heck out of them and hung them.

I got no runs, but some parts were left a little on thin side. I didn't fill or sand them at all.. Just sprayed one thin layer, let dry 30 mins and sprayed final layer. This is recommended on this paint. It has some inhibitors and its possible to paint it on wet on wet as a single medium.

I'm pretty happy with it. I didn't try to make it a show piece, just nice to work on.

Some pics.

1) Masked and hung

2) First thin layer, had to give small tired compressor a break.

3) Second layer.

4) Unmasking took almost as long time as masking it. I was afraid to glue masking tape somewhere painful to reach.

5) Masks out. Have to let them dry overnight.

Haven't done much spraying long time and it shows. Next time I might even use filler. happy I didn't use it today. This was my only whole day off and weather report is threatening plenty of rain for the rest of the week.

Pekka

[awemawson]

Looking good Pekka 

You'll have a fine little bench drill when that's all back together

[PekkaNF]

Thanks Andrew. I'll appreciate it. Many are showing some real skills. I'm just tagging along with this one.

Not sure if I am going rebuild this as a drill or convert this to a taping stand. Depends a little how arbor dimensions work out. It needs a modification.

Pekka

[spuddevans]

I wonder if anybody reads this, because this is pretty basic.

Oh yes we are reading it all, and while I don't have any projects to apply your techniques to (yet), I am making mental notes for when I do have need of it.

Tim (quietly following along)