Wood Trim - Spraying Latex on Oil

Twister

Guys -

I'm spraying acrylic latex (Sherwin-Williams Pro Classic Acrylic Latex in a white semi-gloss) with an airless sprayer over an oil-based Sherwin-Wiliams eggshell that was sprayed on about 4 years ago.

I've asked around about how to do it and was told that in order to get the latex to adhere to the oil that I'd need to either scuff up the oil painted trim with sanding pads or use a product like Paso. I used the sanding pads.

Question: I was using 'fine' sanding pads because I didn't want to overscuff the trim, but after I vacuum off the sanded paint/powder, the wood trim feels exceptionally smooth. Are 'fine' sanding pads coarse enough to get the latex to adhere or should I try 'medium' grit sanding pads?

chrisn

You should be OK

__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Brushjockey

Smooth is good - what you want to see is "deglossed"- the shine taken off. That will give the new paint something to bite into (actually called "TOOTH")
If it was on a varnish coat ( and sometimes on an oil paint coat ) I like to use a conversion layer- a bonding primer.
Call it insurance.

__________________
"It's better to come here with questions before you screw up than to come here after and ask how to fix them."- JS

Twister

What's a bonding primer?

Brushjockey

Zinsser 123, BM fresh start, Glidden gripper,
Help me out here folks..
A primer whose main function is adhesion...

__________________
"It's better to come here with questions before you screw up than to come here after and ask how to fix them."- JS

Gymschu

Well-stated Brushjockey. Yeah, if I have the least bit of doubt about paint adhering, I use a BONDING primer. BJ mentioned the good ones, I like Zinsser 1-2-3, it's cheap and does what it's supposed to do........give the topcoat something to bite onto.

chrisn

I would also agree with the primer, if I was doing it, but I wouldn't be spaying.

__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

kkeith

I never trust that scuffing is enough to provide a grip-able surface when applying water based paint over an existing oil based paint. Especially if the existing oil based is only 4 years old. I would only use an oil based primer or enamel undercoat brushed on as a conversion coating. I have found the water based bonding primers to not always hold adequately. Having to guarantee my work as a contractor, I can't take that chance.
I don't know if you are a DIY or pro, but if you don't have much experience spraying, you could make a real mess with overspray and buildups and runs. If you are good at spraying, you can't beat the finish of sprayed enamel. I suggest using an Fine Finish Tip which is different from a regular spray tip.

jsheridan

Hey Kevin, welcome to the forum. You'll like it here. There are a lot of HO regulars here who seem to have a good handle on things and are here to seriously learn new things. Makes it all worthwhile. Good first post.
Joe

__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

kt82

"re:"I suggest using an Fine Finish Tip which is different from a regular spray tip."
when using the FF tip with Pro Classic Latex do you find you have to thin the paint
I am painting 1980 laquered oak kitchen cabinets . I have sanded (scuffed) and now want to prime
would I get better adhesion with the S-W oil base primer or a water based bonding primer like 1-2-3?

Twister

For what it's worth, I'm not a professional painter but in the spraying I've done (using a 212 FFT [fine finish tip] and Sherwin-Williams Pro-Classic) I found I did NOT have to thin down the Pro-Classic. The paint bucket said that the tip size was .15 - .17 but the .212 FFT worked like a champ. I've got ceiling crown that looks as smooth as glass.

Good luck!