How to paint steel windows so they don't stick?

I am in the process of painting casement steel windows (opening outward). These have an overlap where there is a problem with paint sticking. They also have a some spots of rust, necessitating rust proof undercoat (I am using oil-based rust-coloured Dulux undercoat as I haven't found any acrylic rust proof undercoat to actually be rust-proof).

I then prime with acrylic Dulux exterior undercoat and then top coat with acrylic Dulux weathershield X-10. However I have problems with the paint sticking on the overlaps.

One window I left open for a week recently (weather mid-20's or warmer every day) and the paint still stuck in spots when I closed it, particularly where the rust-proof undercoat was.

I have decided I should apply it with a pad to get an even coat, and already have sanded off any excess old paint blobs before undercoating. Perhaps I should use ESP over the oil-based undercoat the help the acrylic undercoat stick?

Other ideas I have had are: 1. rub candle wax on paint before closing. 2. Spray paint with oil on the overlapping bits (spray can or my Wagner HVLP sprayer). 3. Use thin oil paint on the inside of the casement overlap (saves one layer of primer). I tried this yesterday when it was 38 degrees (and 40 today) so it should dry ok - haven't closed the window yet. 4. stick non-stick cooking paper on with painters blue masking tape on the overlap for a while (tried this and it's a bit fiddly and stops you opening the window as the tape doesn't stick to the cooking paper very well and it would probably blow away if the window was open).

Are there any tips to prevent the paint sticking on the overlapped areas?

Waterbased acrylic wouldn't be my choice for this application as it is thermoplastic, and will remain sticky for a long time, the hotter it gets the stickier it gets.

I would have used a solvent based enamel, but I suppose that doesn't help you now.

Probably one of the best things to put on there now is talcum powder, ie Johnson's Baby Powder, just rub it on the inside of the frame, should help.

Whatever you do, don't use anything slicone based if you want to ever re-paint the windows again.

use the wattyl killrust line.....all enamel........never water based paints:oo:

Hi

Remove ANY extra coats of paint where they are likely to touch. If you do this, you will increase the gap between the two "opposing" layers of paint then the chances of the paint sticking is minimised as there is no pressure or less pressure against the two surfaces.

Thanks for the replies. I have removed excess paint and put a top coat of turps based enamel and it is much better.

I have painted some steel windows before with acrylic and not had a problem - I think this particular window had a crap paint job done in the past and one of the earlier paint coats did not stick very well to an underlying coat. Some parts of the earlier paint coat flaked off when I was removing excess paint - I could tell it wasn't any of my painting because of the colour. This was on the underneath of the opening casement so I didn't prep very well there before I painted.

Anyway I'll be using turps-based enamel in the future, at least for the parts of the window that might stick.

good to hear all is well.....remember to use ONLY enamels, when next time they need painting at least you will be able to sand them smooth. also the paint build up wont be as thick as acrylic

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Originally Posted by Slobba

good to hear all is well.....remember to use ONLY enamels, when next time they need painting at least you will be able to sand them smooth. also the paint build up wont be as thick as acrylic

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I've done 4 more windows now - all with Wattyl KillRust then White Knight Rust Guard on top (to get a flat white finish). Not a great fan of White Knight paints but theirs is the only flat white rust proof paint around AFAIK.

I suppose previously the windows were done with enamel so I haven't bothered with undercoat (except over new Norsdjo Super Putty) and it is sticking perfectly. Saves time too.

I have noticed that the oil-based paints don't fill cracks as well so prep is more important. For example, some of the old paint has very fine crazing in it - I have concluded that you need to strip any crappy paint before repainting.

BTW, I have been masking the window with masking tape and paper and using spray cans. The spray cans go a long way - I'd about it's less than one can per window. Saves a lot of time. You spend more time masking but the coats are quick and easy to apply. KillRust applies better than White Knight but doesn't come in flat white. My windows are not up to being done in Gloss!

I have a can of White Knight Rust Guard in the same colour to touch up with a brush all the bits where the spray doesn't penetrate (fine cracks and holes). I am using Ezyclean brush cleaner which is another great time saver for cleaning brushes of oil or acrylic paint.

Obviously spray cans cost more but I am happy to pay a bit extra to save a lot of time. What's more is that I now enjoy doing it rather than hating it - so it is getting done far faster. I reckon the 4 windows I've done with spray cans and masking took about the same time to do as one window with brush with no masking. (Brush with masking is probably fast as well but the application is not as even by my unskilled hand.)