Oil based or latex primer for exterior?

Chris StrombergerNovember 18, 2005

I'm very confused. I have an older house that needs repainting outside. There is some bare wood from a new addition we had put on (so eaves, fascia are bare). There is also existing trim that needs to be sanded and painted.

Let's just start with the bare wood. Should I use an oil based or latex primer? The guy at HD recommended a latex primer, which I got and have primed a small section (lots more to go). I have since read that oil based has advantages. What is the best way to go, and why?

Any basic tips appreciated.

Thanks,

Chris

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Michael_H

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

    Bookmark   November 19, 2005 at 7:01AM
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chisue

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.

    Bookmark   November 19, 2005 at 5:39PM
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Chris Stromberger

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

    Bookmark   November 19, 2005 at 6:13PM
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Michael_H

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

    Bookmark   November 19, 2005 at 6:52PM
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tom_p_pa

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.

    Bookmark   November 19, 2005 at 8:23PM
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Michael_H

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

    Bookmark   November 20, 2005 at 9:20AM
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chisue

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.

    Bookmark   November 20, 2005 at 11:24AM
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Chris Stromberger

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

    Bookmark   November 20, 2005 at 12:15PM
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Michael_H

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

    Bookmark   November 20, 2005 at 4:27PM
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corgilvr

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.

    Bookmark   November 20, 2005 at 5:29PM
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Michael_H

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

    Bookmark   November 20, 2005 at 6:19PM
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infodiva

I can share my experience - I have an old house, and the porch was peeling like crazy down to the bare wood. I stripped it completely, and then primed with a good oil-based primer. Then I painted it with two coats of latex porch paint. In four years, it has not chipped or peeled AT ALL.

At the same time, I prepped and painted on the back of the house. I used a latex primer and two coats of latex paint. It's now peeling. I don't know if it's because this part of the house gets more sun, or what. I do know that I decided, based on the porch, to prime the front of the house with oil based primer. I think for wood that's been exposed to any weathering, and is therefore a bit dry, it's a good idea. But I don't think it's necessarily the only way.

My 2 cents.

    Bookmark   November 23, 2005 at 3:40PM
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corgilvr

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!

    Bookmark   November 23, 2005 at 4:01PM
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Michael_H

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

    Bookmark   November 24, 2005 at 7:34AM
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corgilvr

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!!

    Bookmark   November 24, 2005 at 1:48PM
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jerry_nj

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.

    Bookmark   December 1, 2005 at 9:01PM
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tommy54

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

    Bookmark   April 13, 2009 at 8:26PM
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jts11791_yahoo_com

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.

    Bookmark   June 8, 2011 at 1:50PM
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