painting over old oil based paint?
#1
10-15-14, 06:51 PM
painting over old oil based paint?
hello
i need to paint over an old wood exterior window frame, i think the old paint is oil.
i have been told the rule is to never put latex over oil (correct?)
i will sand and scuff up the paint to the best of my ability.
the frame is black so if i use a primer i would need to use a dark primer but as far as primer goes i only see white as a choice? is there such a thing as a darker primer for surface prep when the finished color will be dark?
what would be the best way to go about this, and what is the usual method for painting over old oil paint either exterior or interior?
also what are the best type brushes to use for oil / to use for latex?
thanks for the help
i need to paint over an old wood exterior window frame, i think the old paint is oil.
i have been told the rule is to never put latex over oil (correct?)
i will sand and scuff up the paint to the best of my ability.
the frame is black so if i use a primer i would need to use a dark primer but as far as primer goes i only see white as a choice? is there such a thing as a darker primer for surface prep when the finished color will be dark?
what would be the best way to go about this, and what is the usual method for painting over old oil paint either exterior or interior?
also what are the best type brushes to use for oil / to use for latex?
thanks for the help
#2
10-16-14, 03:44 AM
Basically you should never apply latex over oil base enamel on the interior unless you first coat it with a solvent based primer. The exterior is different as it's generally ok to apply latex over weathered oil base paint. If the the sheen is scuffed up [sanded] and the oil paint is clean [including rinsing off cleaner residue] it should be ok to apply latex paint directly to the old oil base paint.
Natural bristle [usually hog hair] is best for solvent based coatings. Nylon, polyester or a nylon/polyester blend are best for water based coatings. I prefer the n/p blend. There is a big difference between a quality brush and it's dime store counterpart. While a quality brush might seem expensive, it will last a long time if you clean and store it properly. Even though I have yrs of experience applying coatings with a brush, I'd be hard put to do a good job with a cheap brush.
Natural bristle [usually hog hair] is best for solvent based coatings. Nylon, polyester or a nylon/polyester blend are best for water based coatings. I prefer the n/p blend. There is a big difference between a quality brush and it's dime store counterpart. While a quality brush might seem expensive, it will last a long time if you clean and store it properly. Even though I have yrs of experience applying coatings with a brush, I'd be hard put to do a good job with a cheap brush.
#3
10-16-14, 06:01 PM
Thanks for the detailed explanation, it helps a lot.
So provided the exterior is cleaned and scuffed well would it be ok to just topcoat with a black latex and forgo the priming?
What are your recommendations for good quality brushes in both natural and poly? I don't mind paying a few extra dollars for good quality rather than fuss with inferior products. (Btw, what about good quality rollers)
Also, what's the solution for a darker primer when the top coat will be a dark color like black?
Thanks for the help
So provided the exterior is cleaned and scuffed well would it be ok to just topcoat with a black latex and forgo the priming?
What are your recommendations for good quality brushes in both natural and poly? I don't mind paying a few extra dollars for good quality rather than fuss with inferior products. (Btw, what about good quality rollers)
Also, what's the solution for a darker primer when the top coat will be a dark color like black?
Thanks for the help
#4
10-16-14, 06:16 PM
Group Moderator
You can have primer tinted.
Purdy tends to be the top of the line brush and that's mostly what I have. Drawing a blank on roller covers at the moment, we'll have to rely on Mark for that apparently
Wait, Wooster?
Purdy tends to be the top of the line brush and that's mostly what I have. Drawing a blank on roller covers at the moment, we'll have to rely on Mark for that apparently
Wait, Wooster?
#5
10-17-14, 03:57 AM
I'm also partial to the Purdy brand. Yachtsman makes decent low priced natural bristle brushes. Generally the price of the brush is a good indicator of it's quality and it helps to prick the correct brush for the job at hand. I forgot to clarify earlier 
natural bristle brushes are for solvent based coatings only! water and latex paint will swell the natural bristles making the brush useless except for a duster.
When tinting white primer to go under black [or other very dark colors] it's best to tint it a medium to dark grey - there is only so much tint you can add to primer or paint.
Wooster is probably the roller cover brand I use the most. Sureline is also a good brand, again price is usually indicative of the quality. I'm an old school painter and don't like the synthetic roller covers, I almost always use a lambswool cover. They are the most expensive and will wear quicker if abused but I like the way they disperse the paint along with the fact that they have less roller spray.
natural bristle brushes are for solvent based coatings only! water and latex paint will swell the natural bristles making the brush useless except for a duster.When tinting white primer to go under black [or other very dark colors] it's best to tint it a medium to dark grey - there is only so much tint you can add to primer or paint.
Wooster is probably the roller cover brand I use the most. Sureline is also a good brand, again price is usually indicative of the quality. I'm an old school painter and don't like the synthetic roller covers, I almost always use a lambswool cover. They are the most expensive and will wear quicker if abused but I like the way they disperse the paint along with the fact that they have less roller spray.
