Working with MDF (cutting, painting/finishing, gluing, etc.)

[javeryh]

Is there any reason why using biscuits for joints is a bad idea for MDF?  It looks like it will work nicely but it doesn't hurt to ask...

Thanks.

EDIT:  Changed to general MDF thread.

[elvis]

Biscuits are wonderful for hiding join work, plus they give a very accurate finish.  Nicely line dup edges, and no indication of where you've joined things (unlike countersunk screws and nails, which can often show).

Plenty of cabinet makers use them for all sorts of items.  And as most people will tell you, with MDF it's generally the glue that does all the work.  Nails, biscuits and other things are pretty much there to hold it in the right place until the glue dries.

I'm a "screw and glue" fan when it comes to MAME cabinets.  The only reason for that is that my mates are REALLY rough on my cabs.  It means extra work with countersinking, putty and whatnot, but they take a beating from even the roughest of individuals.

[javeryh]

Awesome thanks.  I'm planning on using biscuits to line everything up and glue all the surfaces (including the biscuit slot and biscuit).  If I feel like I need to get a little more reinforcement I'll add 1"x1" pieces on the inside of all corners.  I was just worried that using a biscuit on the ends of 3/4" MDF might tear it out or something.  I just got back from the lumber yard with it though so I'm about to find out...

[Timoe]

biscuits expand when they take on the glue.  The expansions may likely cause your MDF to split along the endgrain.

[Gambit]

I know that is possible, but never had it happen to myself.  I've seen it alot though in other peoples projects.

I think if you use nice thick MDF and small enough bisquits it should be fine.  Don't over glue either.

[javeryh]

The expansion is a definite concern .. I'm using 3/4" MDF and it seems quite solid... I'm also going to use the smallest biscuits I can find.  Oh well, I'll find out soon enough.

[prOk]

biscuit joinery on edge to edge with MDF is ok, expansion is not an issue provided you use the right width biscuit.   If you're doing edge to surface mdf joinery then a biscuit is not necessarily the best because the sides of MDF is semi finished and smooth unlike the ends and the glue does not adhere well.  I'd stick with the old standby of blocking and air nails before biscuiting.

[javeryh]

Does anyone have any experience with painiting and finishing MDF who would be willing to share?  I'm going to be painting my next cabinet but I'd also like to add some type of thin protective top coat in case something gets spilled.  Any thoughts on paint types, roller types and finishes?

Thanks!

[spacies]

Always prime first.
Then lightly sand.

Try find some acrylic enamel and apply in thin coats with a sponge roller. It will be touch dry in 20 mins and able to be re-coated in a couple of hours. Its great stuff and the quick dry time means you can finish your painting in a day.
Remember to paint indoors if you can as bugs and dust love wet paint.

Lightly sand between coats.

For a finish clear coat, I have used an acrylic clear floor varnish. The satin finish looks great and is VERY tough.

I now spray almost everything but when I first started the roller and brush did just fine.

A handy tip between coats is to put your roller, tray and paint brush in a plastic bag and stick it in the fridge. This means you dont have to clean it between coats and the paint wont dry on the roller etc because of the cold temp.

Dont try to cover it it one go. Take your time and you will do just great!

If you have to use enamel (oil base) then make sure it is thinned out with Mineral Turps and definately paint indoors because touch dry is a couple of hours at least! You will end up with dust and bugs all over it.

[prOk]

for the best finish always spray the paint on vs. rollers.. but rollers are ok if you can't get a sprayer.

[elvis]

Remember to paint indoors if you can as bugs and dust love wet paint.

Good advice.  I painted my first cab outdoors at dusk, and spent the next day sanding the sandflies out of the paint.  Harsh learning experience, that was.

for the best finish always spray the paint on vs. rollers.. but rollers are ok if you can't get a sprayer.

http://benchmark.mameworld.net/cab1/images/036.html

Black 80% gloss enamel with a mohair roller.  Worked just as well as a spray gun, but with easier cleanup.

The only reason I didn't go spray was because I couldn't find a jet-black paint with water cleanup.  If I was doing a different colour, I would have gone the sprayer with water-based paint I reckon.

[prOk]

If I had a nickel for everyone that claimed their roller was as good as a sprayer       You can get decent finishes sometimes with a roller, but it will NEVER be as good as a properly sprayed on finish.

[elvis]

If I had a nickel for everyone that claimed their roller was as good as a sprayer       You can get decent finishes sometimes with a roller, but it will NEVER be as good as a properly sprayed on finish.

I'm not picky.  This is a home hobby for me.  I'm not spraying vintage cars or anything.

[prOk]

How can you say you're not picky, and claim the roller finish is just as good as spraying at the same time?   That just confuses the daylights out of someone that might really be looking for a real answer in the future

[nostrebor]

Spraying vs. rolling will give decidedly different finishes. Both can be done quite well, but the roller method will always have more texture than a sprayed finish. Where you have to be careful is in the fact that a poorly sprayed finish, applied by a novice with a spraygun, can be disasterous. If you have spray equipment, and know the proper techniques to use it, it can produce a finish equal to or better tahn factory cabinet finishes. If you don't have the equipment, and have never sprayed anything, you'll probably get better results with a roller in the end.

I personally spray my cabinets, but I restored cars for years, so I have the gear and the experience.

[elvis]

How can you say you're not picky, and claim the roller finish is just as good as spraying at the same time?   That just confuses the daylights out of someone that might really be looking for a real answer in the future

Goodness me.  What a pedant.

The finishes on spray and roll both look "good enough" to me.  Sure, they are different.  Spray when done correctly gives a flat mirror finish.  Roll will always give a textured finish.

Is one "better than" the other?  I don't think so.  They are different, and at the end of the day it boils down to personal preference.  I like the slight texture the finish has on my cab.  It also helps mask fingerprints a little better than a pure mirror finish that would require constant cleaning to wipe away grubby children's fingerprints.  But that's not to say that the finish is superior in any way to spray.  Again, they're different.  Apples and oranges.

So, when it comes to spray vs roll, I'm not picky.  They're both different, but from a "pretty" or "ugly" point of view, I find both to be "pretty".

If I was a pedantic sod and want a super-shiny finish akin to a showroom car, then sure I'd have an issue with the above.  Me, I care more about the games than the finish of the cab.  Hence the phrase "I'm not picky".

Is that clear enough for you?  Or do I suffer yet another round of criticism for not being anal enough about the finish of a homemade MAME cab sitting in a dark gamesroom underneath my house where no-one but my kids and I venture?