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We were just awarded a small contract
for some built in casework and the
specfications call for construction out
of MDF with us supplying the finished
installed units primed and ready for
finish painting by others and I was
hoping to hear from some others
regarding what you all feel is the best
primer to use for MDF. I have seen both
excellent and poor paint jobs on
casework constructed out of MDF on
projects we’ve installed but built by
others so I looking for recommendat
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I use MDF primarily for paint-grade raised panels for wainscoting.
While it does machine well, I use a paste pore filler on all cut edges that will be painted. You can still get a decent finish by just sanding and priming, but it's still a bit rough. The pore filler brings it up a notch. This could be important since you're delivering this primed only.
I use a good quality oil-based primer and follow it up with two coats of oil-based paint.
*I use zinsser shellac based primers. They dry quicker than alkyd, cleans up easier, and knocks down better than alkyd.
*Jerrald - is there some way for you to find out who the painter will be and ask him/her which primer and how much prep? Seems like you might avoid a lot of finger pointing later if you could coordinate efforts now. Just a thought. - jb
*I would agree with Jim, you really should check to see what the top coat is going to be and get his recommendation, to avoid trouble down the road.If the topcoat is to be oil or acrylic, the oil base primer would work for both, as would the fast dry primer.If they were going to use a lacquer based product or epoxy based, you would need the primer for those products.
*Thanks for all of the advice you all have contributed so far. Now I'll fess up and be honest with you all. I already have some of my own strong opinions on primers and my reasoning behind asking was to get some second opinions and also hopefully open up some new horizons I hadn't already considered or explored. My company in addition to fabrication, and installations for interiors we also paint although we paint effects. What I mean is that we if it's a straight forward walls and trim job we generally sub that out but if it's and effect, faux finish, or mural we do that ourselves. Most of the jobs whether we do the painting or not I usually write the specifications for the project so that we know it's going to be done right. I often find I know a lot more about painting paints and primers than a lot of the painting trade contractors I see out there in that I am always reading to keep up on new materials and techniques as well as trying them out myself. We only started seeing and using MDF in some of our installations about six or seven years ago so the book is still wide open on it as far as I'm concerned except for one thing. Latex ( water-based) primers just don't cut it on MDF. They all seem to sit on top of the surface instead of "bonding" with it and scratches and scuffs right down to the MDF substrate when using water-based primers seem all to common and easy. While I have a lot of specific choices for primers based specifically on the material being primed and the intended finish coating generally speaking what I like and have been pleased with so far with regard to MDF are Zinsser White Pigmented Oil Based Primer Sealer (AKA Cover Stain) and Benjamin Moore Alkyd Low Lustre Metal & Wood Enamel Primer. I like the Zinsser White Pigmented Oil Based Primer Sealer because it available just about anywhere and it has a fair amount of body to it for a primer that penetrates and bonds well. I like the Benjamin Moore Alkyd Low Lustre Metal & Wood Enamel Primer because it tenacious in bonding to a wide range of surfaces in addition to MDF, has a lot of body for a primer, and has a outstanding reputation for protection against moisture.While there won't be any MDF machined shaped exposed edges on this job I like Mongo's idea of using a paste pore filler so I'll give it a test. Using the Metal & Wood Enamel Primer from Ben Moore with all of it's body sealing the edges have never really been a problem but it's certainly worth a test.Reinhard's recommendation of Zinsser shellac based primer I like too although I find the shellac based primer doesn't seem to have as much body as the oil based but that's sort of a subjective based opinion in that I have never actually used the two together in a side by side real time comparison. As for the quick dry aspect of it that's one of the reasons I sometimes prefer the slower time of the oil. When we're on a job installing trim that for some reason hasn't already been primed it’s a little bit easier to keep a "wetted out" roller of the oil based around all day than it is the shellac based. While the oil dries in about an hour the shellac based just dries a little too fast unless you are going to clean up each time you use it.I also agree with both Jim and Barry on meeting and or working out the finish process with the painter whenever possible. I can't tell you how often we find that we could have saved our clients or co-workers a lot of trouble and or work if they had checked with us first regarding our specification or requirements for a project. While that's not always possible in real world situations working together with other trades rather than working around other trades is preferable in our minds which is jus one of the reasons we prefer a design build approach to project management.Thanks again for the comments and I'm wondering any of you have any comments or experience regarding Hascolac by Schreuder? I love the paint and find it performance superb but I find it a tough sell at times because of the price. Their Primer/Undercoater is fantastic and now
*Jerrald: I've not run across Hascolac, do you have a number or web site for them? I would tend to agree with you about the difference in build up between the oil and shellac based products.I haven't used acrylic(latex) on MDF either which is why I didn't mention it, but since we know oils days are probably numbered, what with all the changes in the formulation, I have tried the the newer 100% acrylic's with some success.Anyway, I don't know if you tried the 100% acrylic primer or not, but while they are getting closer they just don't seem to have the same durability and leveling of a good oil, yet.
*Barry you can find information regarding Hascolac by Schreuder at http://www.finepaints.com. I've only seen the paint in and around the NY metropolitan area and even at that it's still sort of hard to find but I think it's great stuff. I would categorize the finish as being "marine" like in that it will really hold up to severe environment conditions. On of the neat things about it too is that the finish while thin is extremely tough and it levels so well I often say it's impossible to leave brush marks when using it. They also have a product called Swedish putty that we've use to give a glass like finished surface to a built up molding installation we did last spring that you might want to check out too. I haven't found a acrylic primer that I like on MDF yet even though I have acrylic primers that I like for a lot of other surfaces. There is something about the surface density of MDF that just seems to make for a poorer bond than with oil based primers. I was wondering if a pre-wetting of the surface or the use of a flow treatment like Flotrol might improve the acrylic primers bonding power or maybe there is a new acrylic primer out there I just haven't heard about yet, which is I guess why I started this discussion