Wood finishing question

[dsrviola]

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Hello all,

I can finally see the light at the end of the tunnel! Cabinets are almost ready for veneering (all sides except the front baffle.) I'm planning on painting the front baffles to match the black frames on the accuton drivers that I'm using. (I'm guessing the closest finish would be an eggshell finish.) The front baffle is very complex. (see picture) I'm filling cracks/ breaks between pieces, but since it's plywood (and mare than a little complex) it's never going to be perfectly smooth. It's my understanding that you're not supposed to sand primer. I was wondering if there was some kind of hard core (thick) primer that I [i]could[i] apply and then sand until smooth. I was just planning on using black from a spray can for application. (shrug)

Any comments or suggestions greatly appreciated. Thanks!

[PMazz]

Bondo is your friend.

[CraigJ]

How about Dennis H's idea of using drywall compound. Also, sanding primer works for me, especially when I use multiple coats of primer.

Craig

[jliedeka]

I would try to sand the wood as smooth as possible before priming. You can sand primer but I only do that to get rid of any caterpillars. Primer doesn't really fill in even small voids very well. Whatever your wood looks like is going to show, to some extent, through the finish. Eggshell is probably better than gloss for that but you still want the wood smooth and clean.

Jim

[dpc rep]

--------------------------------------------------------------------------------

Hello all,

I can finally see the light at the end of the tunnel! Cabinets are almost ready for veneering (all sides except the front baffle.) I'm planning on painting the front baffles to match the black frames on the accuton drivers that I'm using. (I'm guessing the closest finish would be an eggshell finish.) The front baffle is very complex. (see picture) I'm filling cracks/ breaks between pieces, but since it's plywood (and mare than a little complex) it's never going to be perfectly smooth. It's my understanding that you're not supposed to sand primer. I was wondering if there was some kind of hard core (thick) primer that I [i]could[i] apply and then sand until smooth. I was just planning on using black from a spray can for application. (shrug)

Any comments or suggestions greatly appreciated. Thanks!

Your level of finishing experiece and access to equipment, along with the budget allowed are going to determine what products you use and how the final outcome appears.

To fill the cracks/crevices and voids you are going to need a 2 part filler. "bondo" will work, but is made for filling larger areas and greater thicknesses. If you can find an automotive paint and body store near you they will have a 2 part polyester putty (often referred to as "metal glaze", "skim coat", or "glaze coat" ... every manufacturer has a different name for it) that is a little thinner bodied than body filler and sands much smoother for a better final finish. There is also a sprayable version of this type of filler (manufacturer, Evercoat, called Slick Sand) that works best when sprayed, but can be brushed or rolled when thinned properly. Any of these types of fillers are meant to be sanded before priming and all of them require some sort of primer on top of them before finishing.

The only primers that are not meant to be sanded, in general, are for architectural type coatings (house paint type coatings) or certain epoxies and polyurethanes for industrial applications. This is not to say that you cannot sand them, but they are not really designed to be sanded because they are either not designed to fill, or they dry to hard or soft to be sanded easily.

If you use the filler above to fill and smooth out all the endgrain and voids, you can actually get a pretty good finish with aerosol cans from a hardware store. The primer is a low build, but if all the imperfections are smoothed out before you prime, it should only take a few applications with sanding in between. Once it is primed and sanded smooth you will be ready for your topcoat. If you get a semigloss or satin, you can spray it smooth until it is covered and then back off your distance a little more and put a kind of texture on top of your already smooth, covered finish.

Hope it turns out like you want, and keep us posted with your progress.

Brad

[Alan P. Oliver]

This might help, I would use a 240 or 320 sandpaper with sanding block.Then use a sanding sealer, or thin 50/50 chosen paint cutting back, with 320/400 lubricated abrasive paper (zinc stearate).Then use chosen paint neat, apply light coats cutting back once again, this time use progressively finer wet/dry paper. 3 or 4 coats should do. Hope this helps. Alan

[seattle_ice]

If you coated the entire thing - front, back, edges - with a coat or two of thinned fiberglass resin, then sand with 60 grit, then skim it all with a layer of hi grade body filler (Bondo, but not bondo brand), then skim it all with finishing putty, you will get a very good quality base for primer.

It is a lot of work, but not horrible, and that is how I have finished many custom boxes in cars for years. The resin soaks in to the wood (particularly the edges) and creates a great base for the body filler to bond to. It also makes the wood very moisture resistant and more dimensionally stable.

My .02 cents

[Lurkalot]

I echo Seattle Ice's suggestion. I use West System Epoxy #207 to coat all machined edges of MDF and Baltic Birch plywood, as this coating very effectively seals those porous surfaces, and provides an excellent substrate for primer and paint.

[seattle_ice]

I echo Seattle Ice's suggestion. I use West System Epoxy #207 to coat all machined edges of MDF and Baltic Birch plywood, as this coating very effectively seals those porous surfaces, and provides an excellent substrate for primer and paint.

You don't necessarily have to use an epoxy resin, although for the minimal difference in price you get a very strong, waterproof coating that still will sand to a very good substrate.

When I do a car box from MDF that is going to be painted, I always lay a layer (or two or three) of woven fiberglass mat over the whole thing, embedded in the resin. This provides a layer on top of all the seams and helps bond it all from shifting from vibrations and road shock. Then I thin some body filler down a little and trowel the entire surface to smooth it out.

Home speakers obviously don't have to withstand anywhere near the same kind of environmental conditions, so that kind of treatment would probably be labled as serious overkill. But if you are going for a high-gloss paint job on some expensive speakers that you have put a lot of work in, you would be hard pressed to come up with a stronger, smoother surface.

Overkill? That's just how I roll. :roll: