40 years ago - probably oil paint on woodwork - acrylic now?

[Rob G]

I have a bedroom that is being fully repainted - it is in a refurbished old cottage, and was painted about 40 years ago so I am assuming the paint would have been oil based.

I have acrylic paint that near enough matches the existing woodwork paint. I see that I should 'rub down' the existing paintwork to key the acrylic to it but what does that actually mean, and then should I use an acrylic primer over the oil based paint?

Thanks for any guidance.

 

[Millwright]

To rub it down simply means flatten the surface, use 120 grit (you might need to give it more attention if there's chips etc). Then your water based will go on top fine, you'll need two coats with a 320 grit rub down between coats. Depends on which paint you're using, some benefit with their own undercoat. Hope that helps.

 

[ericmark]

Since the wood paint I am using is thinned with white sprit, I would assume still oil based? We some times get a water based paint, real pain, as we use a brush can which saves washing out brushes, but it does not work with water based paints, brushes still go hard.

But as far as changing type, in the main paint which is 5 years old or more it does not matter, as said flatten the surface, 1 year old I am finding a problem with, some thing cause the paint to peel on some benches, which are always outside, we have tried to sand off all loose with a belt sander, and the hand remove any which looks poor, we put the seat in the compressor room so quite warm with good ventilation, and still each time we try and paint the old paint start to peel, I have 7 benches to paint, only one is a problem.

The paint is rather expensive, we are a heritage railway so must be in GWR colours, and it seems for years we got it wrong, and we used a colour too dark, seems it had been matched to some thing made dark by the smoke of the years. But it means a wood sealer first, then undercoat, and then a couple of top coats. Time is important, and the instructions with the paint tells us how long before next coat minimum, and how long maximum before we need to flatten the previous coat. Which were followed by the letter, and it still did not last the year.