Replies

1. 
   Mongo_ | Mar 12, 2001 04:27pm | #1

   *
   Use one of the BIN primers the next time you use pine.

   MDF...yes, it can be used, however: don't subject it to areas where it will get wet. Even if it's already primed/painted. It can still balloon. I'd never use it for stool material when trimming a window, for example.

   When choosing a profile to router on the edge of the casing, keep in mind that MDF can be somewhat delicate. Whack the corner of a piece of poplar and it will dent. Whack the corner of a piece of MDF ands there is a chance that a chunk of MDF can fracture right off. I wouldn't use a beaded edge on casing in a high-traffic area, for example.

   It can also split if you try to nail too close to the edge of the board. Pilot holes may be required.

   If you are concerned with painting milled edges, use a paste pore filler on the milled edged of the MDF. When dry, then sand, then prime and paint.

   MDF dust is like fine talc...it'll get into everything. Protect your lungs.

1. 
   Steve_G | Mar 13, 2001 02:25am | #2

   *MDF paints similar to wood on all sides. I woild plan on three coats. One primer and two finish coats. If you're using it on an old farm house, I would use 3/4" and round over the edges of the vertical casing and the vertical ends of the head casing with a 1/8" round over bit. I think you can get it in 5/4" too, so plinths at the bottom and a 5/4" head casing are possible too. I've seen GP Prime Trim (an exterior product) used for interior work too. This stuff will handle moisture and comes in pre cut widths. You will have to hit the edges with sand paper as they aren't always as smooth as they should be for interior work. Check it out at your lumber yard. I'm not sure how it compares $ wise, but it would be alot less hassel and dust than ripping heavy sheet goods.steve

1. 
   Jeff_J._Buck | Mar 13, 2001 05:01am | #3

   *On the last rental rehab we did, in yet another attempt to save the owner a few bucks, I trimmed the whole second floor with MDF ripped from 4x8 sheets. The base was ripped tall, about 7 inches, and the old shoe and cap was reused.....matched the existing old real well. Then, ripped some thinner, about 4 inches, to match the rest of the flat existing trim. Got two BR's and a small hall out of two sheets. Matched the old/existing very nicely, and has since held up well. I was concerned about it living up to rental abuse, but so far so good. No wet locations, and window stool is pine, just to be safe. Owner very happy with cost vs. results. Jeff

1. 
   Mike_Smith | Mar 13, 2001 05:17am | #4

   *all of our exterior trim is GP PrimeTrim..1x4,6,8,10, & 12also 5/4 x 4 & 6...this is my preferred trim...i'll also use cedar or redwood....and we use the other synthetics too

1. 
   Adrian_Wilson | Mar 13, 2001 12:55pm | #5

   *We have a couple of manufacturers in the area who make MDF mouldings to match some regional moulding styles (I wish they had a few simpler shapes though; the advantage is they come in a choice of lengths (7-8' for casing, 12' or better for crown, etc., so fewer joints and less waste than ripping from a sheet). Very clean cut, so no sanding, and it's a nice thick 3/4" , not depot thin stuff. I've pretty much stopped making MDF moulding unless I can't buy what I need.

2. 
   Frank_"Mad_Dog"_Maglin | Mar 13, 2001 02:01pm | #6

   *Kevin,If it were me, I'd make my trim up out of poplar. It's clear, comes in long lengths, is slightly harder than pine and in my area is reasonably priced. It takes paint very well. My local lumber yard as well as my hardwood supplier sell what they call pre cut and milled stile material which is used for cabinet face frames. The largest width is 3" and makes nice casing. Out here it runs about .65/lf.

3. 
   Allie_Bereny | Mar 18, 2001 06:38am | #7

   *How do I put a curve in crown moulding?I have been asked to do some pre-exterior painting repair work on an old Victorian. The gable roofs have a slightly curved kick out at the eaves (a typical detail, I think). Of course, the crown moulding that connects the gable facsia to the roof edge follows that curve. Right now it's pieced together with one inch hunks and aluminum flashing. I would appreciate suggestions on a procedure for fabricating a single piece of crown that follows the curve.Thanks

4. 
   Pete_Draganic | Mar 18, 2001 06:44am | #8

   *MDF is a greatly versatile material and seemingly underated. I've used it a few times in place of paint-grade wood. It is a heck of a lot more inexpensive and durable. It is a good idea to at least slightly round over sharp edges to prevent chipping. I capped off a couple hundred feet of half walls in a commercial build-out I did a few years back, with excellent results and a major savings vs poplar.Pete

5. 
   Stan_Foster | Mar 18, 2001 12:28pm | #9

   *Allie: Its a lot of work making curved crown, but it can be done.I am assuming you want to do this yourself with limited tools at your disposal.In your situation, I would make a pattern of the desired curve for the crown. Measure the depth and height of the existing crown. Place your pattern on some redwood or cedar stock that is milled to the depth of the crown and cut out the curved profile.Depending on how much curve you have and how wide your stock is, you can usually get your curved crown in one piece, if not, there will be minimal joints.Now on the end of this curved rectangular stock you have just cut out, trace the profile of the existing crown on its end, holding this profile at its correct angle.Now the fun part. Run the back side of this curved stock against your table saw fence and set your fence and saw blade height to remove the waste side of the profile you have traced. Keep this stocks edge perpendicular to the saws table ,at the blade, as you make a pass through with the stock.Then move the fence over the width of the saw blade, reset the height to cut just to the line, and make another pass, again keeping the stock perpendicular to the saw table at the blade.Continue repeating this until you have removed all the waste side of the line. You now have a curved crown that has a few dozen steps that need to be scraped down to the crown profile. I just trace the parts of this profile on a one of those triangle edged paint scrapers. You can grind three different segments on this scraper blade to match three different areas of the crown.With a dremel tool, belt sander, bench grinder, or whatever, grind out the profile and sharpen the edge. This will make short work of smoothing out the saw kerfs. A little sandpaper of rough grit wrapped around different diameters will finish the profile, making it ready for finer sanding.This does work and it looks much more professional than many small pieces.

6. 
   Stan_Foster | Mar 18, 2001 01:31pm | #10

   *Allie:; Heres a drawing showing what I said in post #9.

7. 
   Rick_Keevil | Mar 24, 2001 04:05am | #11

   *As a trim carpenter I HATE it. It's heavy, pick up a bundle of base? better get help. Pick up one piece, better get help, (both ends on floor). The dust! Nasty, toxic(at least seems it). Nails leave a crater, needs to be sanded before finish. It also splits eaisly, especially neck base or any small detail. I actually charge more to install, much prefer the fresh smell of pine dust.

8. 
   Pete_Draganic | Mar 24, 2001 04:26am | #12

   *Rick,So, does this mean we should put you in the "don't like" column on the MDF worksheet?Pete

9. 
   Chris_Koehn | Mar 24, 2001 07:26pm | #13

   *I would jast add one thing to the excellent advise offered on the MDF thread (having yesterday ripped up a sheet and trimmed a few doors with it..) When it is power nailed it tends to mushroom out a bit at the surface, which requires sanding down with a sanding block. The sanding, I discovered, changes the texture slightly, which alters the way paint sticks. If you are doing multiple coats (as suggested) it will probably go away- I'll let you know in a few days..Also my wife reminds me that if you look around a bit you can find MDF without any formaldehyde binders. If you don't you can successfully encapsulate the formaldehyde with paint- but you should do it pretty quick, and treat all sides. Formaldehyde is being identified more and more as an indoor air pollutant (esp. in new homes where many materials can off gas it, such as cabinets and counters made from particle board) and in high enough concentrations it can do nasty things to your bod.

10. 
    Adrian_Wilson | Mar 24, 2001 07:52pm | #14

    *Try carving any mushrooms off with a sharp chisel.....cuts them down flush in one easy movement, fill and a light sand....voila. You can get low formaldehyde and no formaldehyde MDF (Medite II and Medex are two).

11. 
    GACC_DAllas | Mar 24, 2001 08:17pm | #15

    *I'm with Rick,I HATE the stuff. We built a whole house full of cabinets with this crap (at the request of the client) and I swear I will NEVER do it again.If you can't afford real wood, then save your money until you can.I wouldn't use reconstituted lumber anymore than I would put re-tread tires on my truck.Garbage. And the dust IS toxic.That's my opinion.Ed.

12. 
    Bucksnort_Billy | Mar 25, 2001 04:08pm | #16

    *Put me in the don't like column, too. I've made a bunch of cabinets out it, cause that's what was spec'ed, and I don't even want to go back to see how they've held up. Last summer, we trimmed a house in it, 3/4" 16'lengths factory pre primed. All the base, door, and window casing. No cross nailig miters. If I had known about the trick of chisling off the nail poofs, I would probably still be there. And ripping a house full of trim from those heavy sheets, and then running 8' pcs of base... Yeah baby, we're saving some money now.Used #2 common for base in my own house, oil-based primer from Duron, and haven't seen any bleeders, yet.

13. 
    Mongo_ | Mar 25, 2001 05:44pm | #17

    *MDF is good for what it is.What it isn't:*Cabinet carcass material*A product to be used near water*Face frame or door stiles, or anything that needs to hold a threaded fastner (hinges, etc).*A whole bunch of other stuff*Anything structuralWhat it is (to me):*A good substitute for raised panels for wainscotting, etc, when paint grade is spec'd.*A pain in the lower back to lift.

14. 
    Allyson_Stiles | Mar 28, 2001 03:59pm | #18

    *I'm another in the "don't like" column. JUNK. Thankfully, we don't get asked to install it anymore. We work on customs, and money usually isn't the issue, especially on finish carpentry. I wouldn't istall it even if asked though. Ditto Rick, Ed and Bucksnort Billy.Billy

15. 
    Art_B | Mar 28, 2001 10:13pm | #19

    *Another b JUNK vote, it's a step down from cottonwood and salvaged old pallets even, and can't even be burnt legally.

16. 
    calvin_ | Mar 28, 2001 11:15pm | #20

    *So, you're telling me I wouldn't like working with mdf. on an upcoming new house trim out. The owner would like me to be happy. I don't think her price showed much savings or not. I can get FJ primed pine that takes paint decent and prep is minimal. I think I'll introduce her to this thread, it's informative.

17. 
    Jeff_J._Buck | Mar 29, 2001 12:39am | #21

    *Give it a shot Cal.....I like the stuff. As with everything...has it's place. Big diff with the premoulded crown......it's much more floppy than wood. And I'm guessing it would break, as opposed to bend real far. Need for a helper goes up. And....I have a Senco nailer. 15 gage. IThe brand of nails I think is Spotnails. I don't have a problem with the mushrooming. Maybe it's the nailer and/or nails. And it can't be beat for tablesaw cut raised panels. Jeff

18. 
    Bucksnort_Billy | Mar 29, 2001 12:58am | #22

    *Jeff, I must be missing something, like, you're getting the good stuff and I'm not. I get the poofs with a pin nailer, as well as a SFN40(could be the Spotnails, I'm using a generic and obviously MDF non-friendly brand). When I've table sawn raised panels I'ne had to prime and sand, prime and sand and then, prime and sand again to get the milled surface smooth. I don't care for the way it machines, or for the way it splits when it's end nailed. The painters I work with don't like it much, either. Cal, just say NO.The stuff is great for jigs, though.

19. 
    Adrian_Wilson | Mar 29, 2001 01:15am | #23

    *Obviously, opinion is divided. I still say it's great as a carcase material, and when veneered, is a premium carcase material; some of the new hybrid sheets are good too (since we've digressed from MDF as a moulding product only). Great paint finish, great machining qualities, and the nail poofs have never been an issur for me. Dust is the only downside.I HATE plywood, on the other hand. Just did a bar with a mahogany plywood top, with a heavy moulding around the edeges. The only reason I used it was because I couldn't get veneered particle core or MDF. Dicking around trying to get perfect 40" mitres on ply is no fun; a sheet can vary in thickness up to 1/16" in different places, it warps, it's just crap...and don't get me started on core transfer and voids telegraphing through the surface. My left arm just went numb thinking about it.Loving the new boards, near the river....

20. 
    Jeff_J._Buck | Mar 29, 2001 01:23am | #24

    *I don't know? I haven't used a whole bunch of the stuff...but maybe I have been getting lucky! For tab'e raised panels...I just cut it on my portable DeWalt, and have the DeWalt 40 series(I think that's the one...comes in a cardboard sleeve)...the face I just sand with the finish paper, the blade marks start at about 120 grit and work up. I do notice more poofing with the moulded stuff, than flat stock I cut from sheets...but still not bad enough where I won't use it. Then again...I do remodeling...not new const or cabinetmaking.....and I expect little problems as a part of the work day! Maybe I'm immune to it! Which brings up toxic......that dust can't be any worse than 100 year old ceiling dust that probably has a little black plague left in it! Jeff

21. 
    GACC_DAllas | Mar 29, 2001 02:06am | #25

    *Jeff,Don't you just love the old asbestos plumbing insulation? I eat that stuff for lunch. I guess a little MDF dust ain't nothing to some folks. "I'll use that MDF stuff if it saves you a few pennies in the short term. If it gives me long term health problems, then at least you saved a few quid. However, I can't be there tomorrow, my back is killing me from carrying all that money saving MDF".St. Joseph, watch over us.Ed.

22. 
    Mongo_ | Mar 29, 2001 02:48am | #26

    *bb (Jeff, too), For the milled (raised) portion of the raised panels, try using a paste pore filler. I use a pore filler from Bartley. I brush it on with an acid brush. Takes a minute or two per panel. Let it sit until dry, then sand. Glass smooth finish. Prime, paint, and paint. Done. I once looked upon this as an inconvenience and a job slower-downer...now I simply make my panels first and treat them with the pore filler. While that's drying I do the stiles, rails, whatever else needs doing. Sometimes by that time the pore filler is dry enough to sand down, other times it need to sit overnight.I've also done the pore filler and let it dry "some." Maybe an hour or two while I do the stiles and rails. It's dry enough where it won't transfer when touched, but still soft where it can be indented with a thumbnail. I've then gone ahead and assembled the stiles, rails, and panels, and simply sanded down the pore filler the next day with the raised panels in place. Not a big deal.Paint grade raised panels is what I really like using MDF for.I'll also chime in that I haven't had the volcano problems that others have written about when nailing MDF. Who knows why? 15 ga nails, BTW.

23. 
    Frank_"Mad_Dog"_Maglin | Mar 29, 2001 02:52am | #27

    *BB,I agree with what you're saying about the MDF raised panels. In my area you can't find many painters that want to go through all the steps involved in sealing the milled surfaces. There is one painter I know of that will finish them but if you figure the extra labor he charges to do so, the customer surely isn't saving anything.As far as in the shop, I still don't see any advantages of MDF over paintgrade wood raised panels. The MDF not only creates all that talcom like dust, but it also dulls carbide cutters alot quicker than any hardwood. I've sold alot of paint grade cabinet doors over my competitors for the fact that I make my panels out of wood.

24. 
    Mongo_ | Mar 29, 2001 02:54am | #28

    *Ed, The dust is an issue...and a phenomenal pain in the rear. And nose. However, I don't use MDF because it's inexpensive. I use it because for large runs of paint grade raised panel wainscotting, it's more stable than wood. (cough...was that a chunk of lung?)For trim? Paint grade it's still poplar for me.Take care, my friend...Mongo

25. 
    calvin_ | Mar 29, 2001 02:58am | #29

    *Ok, now I might not mind it but don't get the crown if I'm gonna put it up solo. Now to the homeowner question. How's it hold up to dogs kids and like that? And a different colored snot on the kleenex. Let the painter prep it and warn them (homeowners)cuz they're painting. Got it. And the mdf is supposed to be less where your from, than primed fingerjointed? I thank you again. This new stuff is confusing. I can understand its place in cabinet work. Are the tolerances of the trim consistant? I'm always turning over stock wood trim to match up the relieved backside assuming maybe then it'll be from the same mill. So, how's it match up with different pcs?Appreciate the information. I'll get a pc and give it a try.

2. 
   kelvin_potter | Mar 29, 2001 03:10am | #30

   *
   Was looking at using Mdf sheets ripped down for window and door casing. I was going to use No 2 pine but the knots always bleed through even though i use Sherwin Williams best paint and primer. I guess i'm suppose to pretreat with shellac? I saw someone on this old house use Mdf to build up a crown molding why not rip the sheets into base and casing. I have an old farm house and i was just using pretty plain trim, with a single router cut ogee on top. I've used the mdf to build up bookcases that i have trimed with solid wood. I cant remember how the edges held paint. Seems a little porous. What would you do? Any suggestions would be appreciated.
   Kelvin