Help with laquer finish

[vinceb]

Hi guys,

been awhile since I've posted here but I lurk and follow you guys' projects some. I'm building a set of six of the Adire kit 61 - I thought about the projects here with the better crossovers but I had the woofers for a year in a box, time to do something with them!

Anyway, I sealed the mdf with shellac primer which went well, then sprayed several coats of primer using spray cans (fraid that's the deal, not a gun). The problem I've got is that while the overall picture is ok, I've got some texture here and there on the 1/2" radius edges and some pits here and there. It doesn't have to be a perfect finish since the room is dark, but I want something I can live with.

What is the best way to proceed to fill and sand the surface to get ready for laquer with some primer already on? I know I should have sanded more before primer now, but at the time I was going to just paint the satin and be done, this laquer bug bit later. So any specifics on grit, sanding block, process, what filler to use, etc would be great given the stage I'm at.

Thanks!
Vince

[EdL]

Vince, If the areas you feel to need the attention are along grain edges, put the spray cans away for awhile and get out the paint brush. Foam brushes work OK at this point.
You (I think) want to add sealer in the areas that need it. Coat/sand, coat/sand until you get those areas looking similar to the rest of the "field".
Let me know if this is headed in the right direction. Try grits in the range of 120-150-180 to see what you feel works best. This will require dispensing some elbow grease.

[PMazz]

If the imperfections are more than what a sealer can handle, try some automotive spot putty. Keep it to a minimum, unless you want to be sanding for a while.

Pete

[RobP]

Hey Vince, if you can get to an automotive paint store, have them mix you a can of high fill primer, then once it drys sand it down with 400 grit use a soft block as not to leave your finger impressions in the finish., that will do the trick. If you want that piano gloss look, have them mix you up a two stage paint system in a can. you could base with the black, let it dry then top coat with high solid clear, wetsand with 1000 grit, re-shoot, wetsand again with 2000 and buff. it will be hard as a rock and ultra shiny.

[BobEllis]

Hey Vince,

Spend a lot of time sanding. Get the primer flat and blemish free with 320 grit on a block. 400 isn't coarse enough for initial flattening. Use a little dish soap in the water, and as soon as the sandpaper starts clogging, change it. Time spent sanding the box (to 220 or better) and primer is the key to a good finish.

Just a minor disagrement here - I don't think you are likely to get a smooth enough spray to go straight to 1000 grit unless you use a pro quality gun properly. Even then... When I have rushed through the grits I got a decent gloss but it looked horrible in direct light looking straight at the surface. Scratches everywhere

Apply a couple of topcoats between sanding again with 320. Only go finer after the topcoat is uniformly dull and wihtout any low spots. You probably should give the finish a week or more to fully harden before going finer than 320. I usually go 400, 600, 1000, 1200, 1500 and sometimes 2000. Be sure to clean up after each grit. You don't want 400 grit scratches when you are rubbing out with 1500. Also, spend as much time getting rid of the 400 grit scratches with 600 as you spent making them, and so on. Going to 1500 or 2000 ought to give you a nice satin finish with a little wax, but by the time I've got that much work in it, I usually polish to a high gloss.

Automotive rubbing compounds and polishes work well. You'll probably want to borrow or rent a good polisher - not the polisher/wax buffer kind you find in Pep Boys, but one with some power. 3M, Meguiars and Menzerna make good polishes. Another polishing option is to buy a buffing wheel and a mandrel to chuck in your drill and use hard polishes. I bought a couple of domet flannel buffs, a mandrel and the two finest grades of Menzerna polishing compounds Grizzly sells for $80 - enough polish for several years. The results were fantastic - I got an incredible gloss, better than I have had using automotive polishes by hand.

If you do this enough to justify a spray rig (the compressor is useful for a lot of other things ) Consider trying PianoLac www.pianolac.com. It is a very high solids water based system that seals MDF in one application, then builds very quickly. Rub out is easier than conventional lacquer, and the gloss is amazing. Also available in clear for wood projects. *** I am just a satisfied customer, no financial or other connection *** Sold in quarts, I spent a lot less than I would have on spray cans and have enough left over for the next project.

[vinceb]

Wow, thanks for all the great suggestions!

I was wondering if the brush with a higher solids primer would help, sounds like it's worth a go on the edges. Ok, this is sad, I have a nice compressor, but the hassle of multiple cleanings of the gun and limited time made the cans appealing. Not to be a wuss here but time is a little short just now and I'd like to be listening to these this year if possible

Thanks for the pianolac suggestion, that might help alot, sounds as though something I could spray and not shoot 10 coats (I just hate laquer thinner, etc) and get what I want. Wait, no, they say to shoot 9 coats if you're going to buff the finish. Well, I'll have to think on this some more, maybe the satin look in the pianolac would be a decent compromise.

Thanks again guys.

[RobP]

Bob, Thanks for the Pianolac link! That is really cool, I am used to shooting custom paint on cars not wood.

Best Regards!

[BobEllis]

Robert,

Pianolac was the first thing I ever sprayed. It took me a few extra coats to get it atomized properly - I overcorrected from big drops that would not flow out to dusty a few times. Arthur, the owner was very helpful and patient with this spraying noob. Now that I have it down I figure I'll use much less base coat. Use less air than you think you should.

The creme pore filler is great. Squeegee it on and it seals MDF in one thin coat you're done - even the seams. Never got bondo or a diluted glue was to seal as well.

[philip_g]

Just curious, I don't see pricing on the website, what does a qt of pianolac run?
Also, for small speakers, do you think an HVLP detail gun would work? I've got a pretty small compressor and 8CFM just isn't going to happen at 40psi.

[BobEllis]

Everything is $18/qt or $50/gallon except the rub cut oil, which is $15/qt, at least that was the pricing when I ordered it in August.

Yes a detail gun works - with less waste than a big gun. I was spraying less than an ounce per coat once I got it dialed in. Cabs are about 1 cubic foot. note that he recommends a 1 mm tip.

[philip_g]

cool!
I'll try that on my next project!