Painting cast iron guidance please

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Painting cast iron guidance please

This topic has 7 replies, 7 voices, and was last updated 25 January 2017 at 10:20 by Nicholas Farr.

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24 January 2017 at 20:58 #279976
choochoo_baloo
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@choochoo_baloo
As part of my ongoing Myford ML7 maintenance, I have decided to repaint one of the badly painted cast-iron raiser blocks. Firstly the before:

And the newly bare cast iron:

Having watched this excellent video of Myford restoration, https://m.youtube.com/watch?v=sVXvBxLG6fU , the chap says a 'spot putty' needs to be aplied to replicate the 'spray putty' texture originally applied by Myford?

I was planning to simply spray red oxide primer, then finish with spray gloss Myford grey. Can someone elaborate why or indeed if, I should do this puttying stage, and generally whether my plan is correct for cast iron.

Thanks in advance.

Edited By choochoo_baloo on 24/01/2017 20:59:35
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24 January 2017 at 20:58 #32885
choochoo_baloo
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@choochoo_baloo
24 January 2017 at 23:24 #280008
duncan webster 1
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@duncanwebster1
The putty stage is to fill in the surface irregularities to achieve the very smooth finish that traditional machine tools had. It has no other function, if you don't mind the surface being irregular don't bother.Isuppose it helps when cleaning. Various people have recommended using car body filler.
25 January 2017 at 08:03 #280025
Hopper
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@hopper
For a surface like that you can just spray on a couple of coats of primer, sanding between each coat until you get the desired smooth surface before spraying on the top coat. Might even work better if you brush a good thick coat of primer on there then sand that down. I would not mess about with spray putty for a surface like that. Myford would have used it for convenience and speed to keep labour costs down. Not so much a priority in the home shop.
25 January 2017 at 08:06 #280026
Tractor man
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@tractorman
I’m told that raglan used to apply a thick filler to rough castings and leave them overnight in an oven to allow it to even out nice and smooth prior to painting. A lot easier than all the rubbing down of P38 that I had to do to get my 5 inch looking like new. If you can get a my ford in the oven of course. Mick
25 January 2017 at 09:19 #280037
Journeyman
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@journeyman
You can get a high build filler/primer spray for car body work wich fills small imperfections. Have used it on model boats with some sucess.

John
25 January 2017 at 10:01 #280043
Martin Kyte
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@martinkyte99762
'IF' you use filler primer rather than Isopon body filler, do check that the final paint you intend to use does not react with it. I did a motorbike tank once with high build filler/primer spray and the top coat softened it and then sealed it off when the top coat dried.(does that make sense) I wound up with a soft spot under the top coat and had to strip it all off again. You can buy sealer coat to stop this happening.

regards Martin
25 January 2017 at 10:20 #280047
Nicholas Farr
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@nicholasfarr14254
Hi, cast iron should not be difficult to paint. Use an appropriate primer for the paint your going to use as a top coat. Fill holes or uneven surface by one of the methods above first if you think you need a smother finish, but be sure to remove any grease etc. This photo **LINK** shows my Yankee drill press after just cleaning down and degreasing and then just sprayed up directly onto the bare metal with a Hammerite rattle can, the stand with the cast iron brake disc was done with plasti-kote primer and top coat rattle cans. I had no trouble with either of them taking to the cast iron.

Regards Nick.

P. S. You can see the condition the paint was in, on this drill, by scrolling left on two pictures in the link.

Edited By Nicholas Farr on 25/01/2017 10:42:22
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