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MDF already gets wide use in interior applications anyway (cabinets, substrate between wood veneers, etc) so any other interior application like crown moldings/baseboards don’t present huge problems, especially as a paint-grade material. A couple of suggestions to ease any potential problems… pre-condition the wood by storing it in the area it is to be used, upwards of three weeks if possible, and by all means back-prime the pieces- which should be done regardless. MDF is slightly less stable, but over time and with a willingness to do some touch-up later on, the results should be fine. Easy on the trigger finger if using a nail gun tho… since there is essentially no “grain” to clamp down on the nail by friction. Otherwise, go for it and good luck.
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I do agree with Ed that MDF is probably the worst stuff you could possibly work with as far as dust is concerned. I try to cut it outside or with some kind of dust collector. On the other hand, we use a lot of pre-primed MDF trim and have never had any trouble with it. It's harder than pine or poplar and the quality of trim we get is super. It is also very inexpensive. Less than 1/2 the price of real wood and already primed! If you don't control the climate in your house, you will have trouble with any wood product shrinking or swelling. I don't have trouble with nail holes either. I think it is great for paint grade trim....Just my opinion! I find the Plum Creek brand to be the best for milling your own trim.
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While I prefer stained wood trim, for paint grade applications, MDF just can't be beat.
A couple installation tricks:
1. backer board/blocking. The stuff is not very strong, nor ridgid, so lotsa blocking between the studs is a big help. When installing crown, you definitely need to install a triangular block underneath the MDF to support it and to provide a nailing backer. I also use construction cement/glue as well.
2. Not too much sanding. It is really ready to paint, and is very soft, so easy on the sanding.
*Sorry Mike, I'm left coast. Native SF. Moved to the Sierra Foothills 'bout ten years ago. Dave
*Hey Ed, Sorry for misreading your post. As I mentioned earlier MDF is certainly not my product of choice for trim. It's just as you say, a carpenter can get into a situation where a customer or contractor can't be swayed into using a real wood product whether it's trim, cab doors or whatever. Often times people will listen to my recommendations and sometimes not. All I meant was that I generally have to go along with what they want, and I felt that by doing this does not make me a poor carpenter, maybe just a poor salesman. Mad Dog M.
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I'm about to order interior trim for an entire house and have heard bad things about MDF from wood trim suppliers. In particular is a tendency to expand and contract with changes in humidity. This could be a problem with base trim and crown moulding where long lengths would buckle away from the walls. I'm wondering if anybody has had these problems and if pre-primed stock has the same problems. Is it safe to use as door and window casing because of the short lengths (no miters). Have you used it successfully in baths and kitchens? I'd really like to hear from experienced MDF users, not die hard wood lovers.
Thanks, Dave
*Hi Dave, I have both had those problems you mention and used mdf succesfully. The material came from two different suppliers, the one we had trouble with we found out later stored the moulding outside under a shed. It was out of the rain but exposed to humidity from all sides. A couple of weeks after installation and painting it shrank enough to crack the paint on the miter joints of the casing, the worst joints opened up nearly 1/16". We filled the cracks and touched up the paint and the last I new it was still ok.We used mdf from a different supplier on two other jobs, one whole house and one master bath addition. The bath job had some approx. 6" crown the longest runs were 17', it still looks great at least two years later. The whole house job still looks fine after about three years. This second supplier stored the molding inside in a fairly controlled enviornment. Oh yeah all three jobs were pre primed.I think mdf is very stable if protected from moisture, but the thing about expansion and contraction is since its a homogenious [sp?] product, no grain, it will move alot more in length relative to solid wood which moves across its width primarily and very little in length. The joints that opened up on us were a uniform crack which indicated that the piece shrank in length, solid wood seems to always open up on the heel of the joint when it shrinks. Assuming you can get molding thats been stored right the only other problem I have with mdf is it tends to pucker around every nail you shoot and will look like crap if you dont sand it back down. good luck, Chuck
*David,I'm sorry sir, but if MDF is your bag..........then you are no carpenter. Carpenters are woodworkers. Maybe you're just a "Trim Man". There is no place for MDF in Fine homebuilding. My opinion.Ed. Williams
*I disagree with Ed. There are many good applications for this stuff, and I have found it to be very workable, and fantastic paint grade material. I'm a dedicated woodworker, but I realize that with an open mind, there can be room for these manufactured products.Also, we may as well get used to them. The future doesn't look all that woody to me.Ed, you do use drywall, don't you?MD
*I would have to disagree with Ed also, Though MDF is not my first choice to use for trim, I have to go with whatever my customer (contractor or homeowner) requests. Does this classify me as a "Trim Man" and not a finish carpenter??? I can give them my opinion, but they are the boss. I have installed MDF door and window casing and even some crown moulding in homes with no problems with joints opening up or long runs buckling from humidity. I am in an arid climate however. What I dislike the most about it is the fact that it does dull sawblades and router bits quicker than wood will, and The fine powder like dust generated when cutting and milling it will make you search out a dust mask. MDM
*When it comes to paint grade finishes - I don't think MDF can be beat - not to mention it is an envornmentally (in some ways) friendly material.Stocking the MDF for a few days prior to use will acclimate it to it's new home - minimizing the expansion/contraction thing.Good LuckBuz
*MDF already gets wide use in interior applications anyway (cabinets, substrate between wood veneers, etc) so any other interior application like crown moldings/baseboards don't present huge problems, especially as a paint-grade material. A couple of suggestions to ease any potential problems... pre-condition the wood by storing it in the area it is to be used, upwards of three weeks if possible, and by all means back-prime the pieces- which should be done regardless. MDF is slightly less stable, but over time and with a willingness to do some touch-up later on, the results should be fine. Easy on the trigger finger if using a nail gun tho... since there is essentially no "grain" to clamp down on the nail by friction. Otherwise, go for it and good luck.
*Thanks all, for your responses. I'm goin' for it. Though I love wood and working with it, I've always hated covering it's natural beauty with paint. Since all of the trim will be painted, MDF really seemed like the appropriate material. Dave
*Looks like I stired up the dogs,I'm sorry you guys, but I just can't stand the stuff. It just don't seem right. Have you read the warnings about the dust? I'll fight tooth and nail not to have it in any house I build. I don't always win......we just did a whole kitchen (doors, bulkheads, drawer fronts, the works) out of MDF last year. Then they just put a sanding sealer on it. Ugliest thing you ever did see. I'm still appologizing to the men on our crew for having gotten us involved with that one. Never again. Also never again, that laminate covered in metal. Did a pool house kitchen in that stuff. Never again........Sorry, I'll fight MDF all the way into the future.Ed. Williams
*......hey Ed ..cool your jets....I love MDF... and poplar...and oak....and luan...and Trex...it's all part of the wonderful things we have to work with...I'll give you one...which would you rather use for interior trim , MDF ("dirt board") or factory prime finger joint...and the correct answer is........ MDF, but back prime it, edge prime, don't let in get into a situation where it's going to wick water (same with any cellulose material)..hey , David David Giuliani - ..are you from RI ? do I know you ?