Garden fence advice

[hazey3]

Hello everyone, i'm new to this site. I'm looking for a bit of advice. We recently had a wooden picket fence put up. I wanted to paint it in a light colour so chose pale jasmine cuprinol garden shades. We gave it two coats and it looked lovely. We didn't put on any undercoat or primer as the person who put it up said the wood had been treated. Anyway after a few weeks the paint started to go brown (like cigarette smoke stains). We gave it another coat and it happened again. This has happened a few times now. Does anyone know why this is happening?
We have decided now to paint it black so have got the cuprinol black ash. Should it be ok to paint straight over and do you think it will cover it ok and stop going brown? Any advice would be appriciated. I'm so sick of painting this fence so hope the black will be ok.
Hazey3

 

[misterhelpful]

If you were told the fence had been treated I would assume it has been pressure treated. The chemicals used in this process can bleed through any subsequent coatings, especially light ones like you have used. This usually only occurs with freshly treated (new) timber, and if I recall correctly, Cuprinol actually advises you on the tin to allow treated timbers to weather for a few months before applying their product (at least they used to). You might be ok with the darker colour but it could be worth waiting a while to ensure those chemicals have dried out thoroughly and by then it may be safe to use the lighter colour again.