An ornamental garden gate in softwood. I gave it a few coats of aluminium primer and best quality grey oil undercoat. Mrs W chose a top coat of Farrow and Ball exterior gloss which to my surprise is water based. Anyway it doesn't go on, won't film at all.
Oil and water don't mix. You could try a good wash over with sugar soap and then have another go?
I used oil based primer then water based gloss and there was no problem, but there was a delay of three weeks between primer and gloss.
Bill
I've certainly put modern water based gloss down on old oil based gloss without any problem. Another +1 for sugar soap, and perhaps a better rub-down?
Yes, all these water paints say they are suitable for previously painted surfaces. Maybe I need to prime the undercoat, mad as it sounds. TW
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Thanks, I knew it! LOL!
With less volatile solvents these days I've found that oil based paints take a long time to fully cure/harden - a week or more.
A coat of PVA on top of the oil paint.
Very simple: just paint it again. After a few goes you get full coverage.
NT
My other main observation with solvent based paints comes from cleaning the brushes. I use white spirit and after using to clean the brushes decant it into plastic bottles for future use for brush cleaning.
The pigments/solids in some paints will drop to the bottom of the bottles within a matter of a couple to three weeks leaving most of the white spirit a clear but murky colour. The thin pigment/solid layer at the bottom of the bottle will remain intact when pouring off the top nearly clear white spirit.
With other solvent based paints the pigment/solids seem to stay in the white spirit solution for many months (> 6 months) with the settlement occurring in distinct layers. When pouring off the clearer solution at the top of the bottle the pigments/solids that have sunk to the bottom of the bottle readily mix again.
If its wood, it will probably crack in fewer years than you anticipate as modern wood is crap. Somebody down my road had their gate dipped in some kind of stuff that feels almost like teflon. Its very thick and probably expensive to do!
Brian
The one which caught me out was oil based paint over an acrylic paint, it kind of never dried and went rubbery. Brian
How long was the undercoat let to dry/cure? Often the manufacture will give a drying time or re-coat as 24 hours BUT at ambient temperatures of
20C. If painting at this time of year outside you would have to adjust the times, especially for the night time temperatures.
It's in a unheated shed, but undercoated 4 days previous. you'd think it would be fine, didn't clog the 180grit paper. TW
I have an email from Farrow and Ball who say that likely it is exactly as you say. Low temperature and slow cure. TW
25 years ago the old gate was rotten. I thought it must have been the original softwood gate but at 100yrs old is that even possible?
Anyway a young man made me a new one at a very reasonable price and took considerable care over it but it only lasted 15 yrs, I suspect because as you say - crappy modern softwood.
The new one is assured 'Joinery Quality' SW, whatever that means. I hope for the best.
TW
Pre-war fences and gates around my way used to be made of oak and were left unpainted with preservative or paint.
If your gate was 100 years old it may have also been oak and painting it may have lead to its demise by trapping water between the (flaking) paint and the wood..
I gave waited a while then gave it a coat of some other oil eggshell and waited again and finally the water paint is sort of going on. It will be okay.
Thanks all TW
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