Latex primer, as long as it's a high quality primer. Modern paint technology has eliminated the advantage that oil base would have over water base primer. Zinsser water base primers are superior to most oil base primers on the market.

I hope you're using a quality primer over a clean, well prepared surface. That's the important issue.

Michael

Um...what if the house's existing paint is oil based? For that matter, how would you know what's on there? It seems it would get messy if you have to use two types of paint on a single surface.

OK, so I prime the bare wood w/latex primer. Now, what about the existing wood, which has two definite layers of paint, the top one peeling off, mixed with some mildew and lots of dirt etc. Not well taken care of.

What's the next step there? In another thread ("Exterior repaint 101"), an application of Jomax, followed by scraping/sanding, followed by application of Peel Stop was suggested. So in that scenario, I do not use this same latex primer I used on the bare wood for the cleaned up existing paint areas? What if I sand down to bare wood in places?

Thanks for all the help!
-Chris

ChiSue,

We're talking about primer. Water base primer is fine over oil paint and oil base paint if fine over water base primer. In time, real soon, there will be NO oil base paints sold.

Chris,

I was hoping you'd read the tech bulletin I included with the Peel Stop. It's a special primer to keep paint from peeling. Use it over those vulnerable areas and paint over it just like you do any other primer. Use the other primer in areas where the wood is bare or sound. Don't worry if the two primers touch..it's harmless.

Michael

For bare wood...I would use a stain blocking oil based primer. If you have knots in your wood, they will show through in no time if you use latex. My house has painted cedar trim, and will bleed through unless I get an oil base primer for covering cedar.

First determine what type of wood you are painting to see if it is prone to bleed through, and then proceed. For other painted areas, use latex because it is much easier to clean and dispose of.

Peeling areas with dirt and mildew must be cleaned, scrapped and/or sanded properly. Preparation is the key to a good paint job. If not done correctly, it will just peel again. If you have a very bad surface, I would personally take the time and do it correctly, use an orbital paint sander and remove to bare wood. Makita makes a popular one that runs about $80. That way you are guaranteed a lasting result.

Chris, "if" there are knots to cover on the bare wood you had installed, simply use a spray can of Bin for "spot priming" those spots. There's no sensible reason, economically or environmentally, to go out and buy a quart or gallon of oil primer, dip your brush in it 5 times, then store it in your garage for 5 years, wondering, "what do I do with this stuff?"

You can also use the spray BIN to spot treat ceiling stains, spackling, etc. AND, IT'S NON TOXIC!

BTW, you better get to work. Christmas is near!

Michael

Thanks, Michael. Since I have not personally painted anything in years, I was remembering the "don't try to paint latex over oil-based". So, primer is different!

And, now I know how to fix the knot holes that are showing up in our garage door trim: BIN, then latex paint.

Is this forum great or what? (Thanks to the pros who indulge us.)

BTW, could the OP use a chemical stripper instead of sanding? I know -- chemicals are bad -- but maybe he doesn't want to build up his biceps.

Ditto ChiSue--thanks to all the experts for the invaluable help.

Re those knots, what is best for filling in big knots? It didn't sound like the Crawford's putty was good for big imperfections like that.

Thanks,
Chris

Big knots? The putty will work as long as the knots are primed. Just keep in mind, the deeper the void, the longer it will take for the putty to dry. The minimum dry time for Crawford's is 24 hours.

Where did your contractor get that bad wood?

ChiSue,

You can apply quality acrylic latex paint over old oil base paint. The prep work is the most important part. A good cleaning, a light sanding to dull the surface, and a high quality acrylic latex enamel. OR, if you prefer a primer over the oil finish, I would still sand it first, them prime and paint.

I go the extra mile and prime first because I get paid for complete customer satisfaction, and I HATE to return to fix something that I took a risk doing.

Michael

Okay Michael, the "best" painter in our old town swears by oil based primer followed by the best latex or acrylic, I can't remember which it is. How do I argue with him? If it's any help, we're talking about 150 year old homes that are being scraped down to original wood. He only requires the oil based primer over the raw wood. I was doing it your way before he got a hold of me.

Don't argue with him. He won't listen.

He's probably not 35 years old either, so don't spend time trying to introduce him to a new, improved work method. I'm much older than 35, but I truly enjoy learning and doing what modern paint technology offers me.

Get the facts for yourself and then do what you're comfortable with on your jobs. I know by my experience and proven research that Zinsser makes water base primers that outperform conventional oil base primers. That's a proven fact, through research and field trials.

I use and guarantee what I know is best for my paying customer. I don't argue with other painters in town, I just perform my work in a professional manner using the highest quality materials avaialble to me.

Besides oil base primers and paints being messy to work with, they are environmentally unfriendly and currently being banned in some states. Consider that.

Michael

Thanks! Isn't this what makes these forums so good? I live in PA with lots of temperature and humidity changes. Does that have any effect on the primer/paint issue?

Michael, what about glazing compound that is oil based? The can says to use an oil based primer under and over the glazing. What do you do with glazing compound?

Thanks in advance and Happy Thanksgiving!

info,

the difference is very simple. The prep wasn't adequate before you painted or there was a moisture issue, or loose paint over a poor surface that wasn't resolved prior to priming. It's not the primer or the paint, it's always....preparation and prevention.

Happy Thanksgiving!

corgilvr,

Both water base and oil base are labeled for ideal paint conditions regarding temp and humidity. The applicator is then responsible to decide the "best" window for painting.
Most production painters ignore the label advice! Someday I'll send you a pic of a new store front spray painted in direct sun by one of the largest painting firms in Ohio. A pathetic sight!

Glazing compound that is oil base never dries (remains flexible - supposedly). Therefore, when using it, always prime according to the label. If you don't, the putty will bleed through the topcoat. In this case, which is rare in my community (newer homes), you need to use the oil base primer under and over before painting.

If you read the label on that putty, you'll discover that there are not many days in PA that you can actually use it! ):

I've never re-glazed a wood window. My community is newer, 1975 to present. No need to buy glazing compound. I saw a can on a shelf a few months ago. It was labeled, "best if used by 12/97" that's how well it sells here. LOL

Since the EPA is cracking down on oil base anything, I'm sure manufacturers will be introducing new glazing compounds like siliconized acrylic, etc. that will adhere to water or alcohol base primers.

Read the article below.

Happy Thanksgiving to you!

Michael

Here is a link that might be useful: Old stuff

Thanks, Michael! Our homes are all built prior to 1875!!!

I'm hoping this is the last glazing I will do and will follow directions! Some of the old reapirs just come off in strips. I love to glaze!

Please know that I really try to listen to all you experts! Ask ten painters, guess how many different answers I get? I know you aren't signing a contract with me so I really appreciate your time!

Thanks bunches and a Happiest Thanksgiving to you Michael! You are such a valuable resource to us!!

What is the difference between an interior and exterior primer, oil or latex? It seems both have an appropriate top coat that gives the finish its look, washabilitiy, mildew resistance, sun tolerance, ... you know stuff that is either inside or outside. There are a lot of common needs too. Again, why are there two types of primer, interior and exterior. Yes, I have seen some that say they are good for both, which makes sense to me.

I have a bunch of interior latex kilz primer can I use it on the exterior of my house

I have cedar shakes that are on the house for 10 year and were fastened with stainless steel nail that show. What type of primer should I use oil or latex followed by a solid stain.

My experience in painting over rougher textured T-111 or board and batten exterior siding that's been stained and weathered is to clean and prep as appropriate ( sanding, scraping etc. ) followed by an oil based primer, followed by several coats of a good latex paint. When I've done that knots and stains do not show through , the latex sticks well and it looks great for many years. I know oil based paints are not good for the environment ( I am an active environmentalist) they are not healthy to breathe, they are harder to clean up and they are going the way of the dinosaur. I would like to learn more about these water based primers like Zinsser and if they are as good as claimed, that may be what I use from now on. My next job is painting over a pine ,tongue and groove sided house that has weathered, mildewed and peeling Sikkens Cetol on it. At a crossroad: oil or latex primer? Also want to know more about these emulsions (?) that are added to the topcoat for bonding like Stix. Great thread, Thank you all for your participation.

I love oil paints and I'm pretty ticked that they're going the way of the dinosaur and not being replaced by anything with properties even close to what is being crowded out. Drying time and leveling are my major issues - I'm way over 35 and I'm not as spry as I once was. I need the longer dry times these days or there WILL be brush marks. Where I live (in a desert) acrylic paints dry in about 30 minutes (compared to the 1 hour it says on the can).

That said, acrylic paints are generally way more appropriate for exterior painting than an oil based type. They are more flexible and far less prone to cracking and chalking.

I'd stick with a good exterior acrylic primer and a good exterior acrylic paint.

Will strongly consider that. Thank you.

Professional, licensed painting contractor here. Only age 30, we do very high end work. I do surface testing myself using scientific method and also read a TON of textbooks, literature, etc.

The best primer to use is oil-based or alkyd-based, and I’ll tell you why.

THEN, I’ll tell you why unfortunately some in the industry LIE. And it has to do with money, special interests, and EPA regulations.

1. IN SHORT: Oil-based primer is better than latex primer because of the binder (oil), preventing moisture from intruding into the wood. (Oil and water don’t mix) Wood swells and expands when it’s surface gets wet. The oil primer prevents the rain from entering wood. This prevents paint chipping and peeling. Latex primer- even if it bonds great to the wood- still doesn’t prevent rain from soaking into the latex paint and latex primer, and then into the wood. When the wood expands, the paint chips/peels because paint has low elasticity.

For a more scientific explanation: Ever seen how accidental oil spills in the ocean, result in the oil sitting on top? This is because oil and water do not mix. They cannot mix.

This is because water (liquid H2O) is held together by hydrogen bonds. Whereas oils and fats not have any polar part and so for them to dissolve in water they would have to break some of waters hydrogen bonds, which they will not do, so they remain separate.

All of the paint advancements in the world, cannot change the fact that the binder in latex paint remains water, thus it is WATER SOLUBLE. This is a problem when it rains.

You can paint interior cabinets (just not in bathrooms) with a urethane acrylic (water based) paint and it’s generally fine. But outside wood, where it’s going to rain? It’s a very, very bad idea to use latex based.

WHY THE INDUSTRY LIES:

Paint Manufacturers (Corporations) receive money directly from our USA government as well as European governments, in order to promote what they call “environmentally friendly policies”.

As oil-based paints are less “environmentally friendly” due to a higher VOC count, this results in paint manufacturers and paint stores feeling obligated- generally FINANCIALLY OBLIGATED- to push customers to purchase latex primers over oil based primers, even when oil based primers are much more effective according to science.

Oil-based solid stains have actually been cut out of circulation completely… you cannot buy them in the USA anymore. For oil-based semitransparent stains (which are much better than water based stains), only a few states manufacture them and our state needs to have them shipped in. This is because of EPA regulations.

I want to reiterate that I am certainly in support of helping the environment, and I understand the importance of that. I think both sides of the aisle can and should agree on that. However, I don’t agree with government corruption or misleading consumers in order to push incorrect claims. Any agendas should be based on truth and honesty, nothing else.

There’s a reason the girl, in a comment above, mentioned How she had applied oil based primer to her deck and siding and it held up perfectly, whereas the latex primer and paint over that had peeled. Because latex primer on wood outside, fundamentally does not work on a molecular level. Corruption and EPAA regulations and government funding are the reason why companies incorrectly tell you to do this. But if you get a skilled and intelligent painting contractor, that really knows what they are doing, they’re going to tell you otherwise. And again, I’m 30, I grew up in a time period where I could do experiments/ tests on both oil and latex primers and come to factual conclusions based on the data. I have no bias, except I want to do the best job and make the most money obviously. And jobs hold up better and look better with oil based primer on EXTERIOR wood.