How to hide screw holes and seams?? - AVS Forum
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post #1 of 35 Old 05-29-2011, 07:59 PM - Thread Starter
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Making my first "boxed" sub now. All 4 of my previous subs have been "sonosubs", so very easy on the finishing touches for a new. Well this new one has me stumped. I'm eventually going to have a piano-black finish on it hopefully. But I don't see how that's possible with all the seams and counter-sunk screw holes. How do I make it flush and smooth? Is that what wood filler is for? And how is it really applied?

Thanks guys.

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post #2 of 35 Old 05-29-2011, 08:30 PM
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Piano Black is so time consuming. If you have alot of screw holes on the exterior then personally I'd just finish another way. Piano black will end up magnifying ALL your imperfections and you'll likely see every single screw hole even when you think you sanded it well.

If I was doing piano black again I'd definitely give myself the best chance of having it turn out well by building my enclosure with NO screws on the exterior. Rounding over edges helps alot with seams.

Anyway, get ready to sand/wetsand your entire enclosure 6 or 8 times over, depending on how many clear coats you put on it.

You can use bondo (as per directions) on screw holes. It sands down as good or better than anything.
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post #3 of 35 Old 05-29-2011, 08:31 PM
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I have no experience, but I clearly remember seeing someone use bondo. It works for cars. I don't see why it won't work for subs.

Edit: someone beat me to it.
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post #4 of 35 Old 05-29-2011, 08:37 PM
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I use wood putty applications. Only add about 1/8" layers at a time until dry, then sand once they are sticking out.

I also keep a bucket of sawdust from the same plywood and mix it with wood glue to fill voids and seams. Works well and sands out nicely.
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post #5 of 35 Old 05-29-2011, 08:49 PM
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Bondo works great. I've done many boxes and use it every time. Bondo up the holes and seams for a nice finish for your piano black!

Blasting brown notes for 10 years and counting!

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post #6 of 35 Old 05-29-2011, 08:55 PM
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Bondo is far better as long as it will be hidden under a finish. It is the most stable, works well, cures fast, and sands well. I literally have filled thousands of holes and seams on cabinets in my career with Bondo.

That said, a piano black finish is still the hardest to do.

Sealing/filling the MDF after an initial round of filling and sanding is key. I believe there are auto finish products that help-special filler primers, IIR.

Perhaps an epoxy repair product like Abatron, thinned a little to soak in on the first coat, then a second coat on top. After that, level sanding with nice flat blocks or pads. At this point, the cabinet is ready to spray the first primer coats and then on with the time consuming process of black laquer.

Prep work is paramount here.

Best regards,

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post #7 of 35 Old 05-29-2011, 09:18 PM
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Quote:
Originally Posted by servojohn View Post

Prep work is paramount here.

I agree totally. One of the best ways to 'prep' I can think of for piano black would be to use no screws on the outside. Why fill screw holes when you don't have to? For a first timer doing piano black you can pretty much guarantee you'll see most of the filled holes. I guess it's always a learning curve, I know I learned alot when I painted piano black the first time. Wish I would have known what I do now... and alot more.
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post #8 of 35 Old 05-29-2011, 09:50 PM - Thread Starter
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So the viable options to fill screw holes and seams are:

- Bondo
- wood filler
- wood glue mixed with material's saw dust

?

Is bondo readily available at auto shops? Is there a special "wood kind" that I need to get?

In terms of LFE, size does matter!
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post #9 of 35 Old 05-29-2011, 10:00 PM
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Did someone say Bondo?

I <3 Bondo!!!

Seriously, Bondo works great, doesn't shrink, is easy to fill and sand and drys fast. The picture below is my THT with just over 150 screws in the top. The end result was a nice smooth after some work with the random orbital and palm sander.

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post #10 of 35 Old 05-29-2011, 10:15 PM
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Bondo works great. If you're going to do piano black, it's a lot of time and work, and if you don't know how to hide an imperfection, it may be too much to take on.

You will need to bondo, sand, prime a couple of times, sand, probably prime some more and sand some more, then lay on a number of base coats.

After the base is laid on, you will need to apply a number of clear coats, sand, wet sand, then polish. It's a lot of work.

Also, myn's bondo job is scary
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post #11 of 35 Old 05-29-2011, 10:39 PM - Thread Starter
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So is there a special kind of Bondo for wood? Or can I go to NAPA and just get automobile Bondo?

In terms of LFE, size does matter!
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post #12 of 35 Old 05-30-2011, 02:41 AM
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Quote:
Originally Posted by Favelle View Post

So is there a special kind of Bondo for wood? Or can I go to NAPA and just get automobile Bondo?

I haven't tried it, but all auto parts stores have bondo on the shelf, and that is what folks are recommending.

I just bought some today, but I noticed that there was a product called "Bondo Home Solutions all purpose putty" right next to the normal automotive bondo. So I bought the home stuff to give it a try. Maybe they enhanced it to work even better than the normal stuff.

-Max
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post #13 of 35 Old 05-30-2011, 04:31 AM
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why even use screws???

Tim
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post #14 of 35 Old 05-30-2011, 07:01 AM
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Quote:
Originally Posted by notnyt View Post

Bondo works great. If you're going to do piano black, it's a lot of time and work, and if you don't know how to hide an imperfection, it may be too much to take on.

You will need to bondo, sand, prime a couple of times, sand, probably prime some more and sand some more, then lay on a number of base coats.

After the base is laid on, you will need to apply a number of clear coats, sand, wet sand, then polish. It's a lot of work.

Also, myn's bondo job is scary

This is correct. I have achieved a decent piano black finish, and the best way to do it is a perfect sanding, multi-layer primer, cure (~1 week), sand with 320-400 grit, if you sand down to wood on some areas repeat process, apply multi-layer base coat, make a shelter so dust doesn't adhere to it during drying, cure (~ 1 week), sand, repeat base coat process if you see primer after sanding, apply multy-layer clear coat, cure (~1 week), wet sand (800 grit), apply more multi-layer clear coat, wet sand (800-1000 grit), polish, repeat clear coat if not perfect yet.

Have fun
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post #15 of 35 Old 05-30-2011, 07:03 AM
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Quote:
Originally Posted by tundrSQ View Post

why even use screws???

Getting a brad nailer is where it's at. There are still holes but they are tiny easy to fill holes as opposed to 1/4" diameter screw head holes.
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post #16 of 35 Old 05-30-2011, 07:20 AM
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Quote:
Originally Posted by Favelle View Post

So is there a special kind of Bondo for wood? Or can I go to NAPA and just get automobile Bondo?

Yes, the least expensive lightweight bondo from there or the hardware store is fine.

If you haven't built the cabinet yet, avoiding screws and just clamping up the assembly would be better for a piano black finish. As mentioned, if fasteners have to be used, a small finish nailer will be much better.

Also, miter all the joints so no MDF edges are exposed where they might be seen. The different texture, expansion, and factory finish makes it much harder to hide under the finish.

Layering a few coats of epoxy like the Abatron product will help provide a harder, sealed, and smoother base(if sanded with leveling blocks and pads) for the primer/paint/clearcoats to be sprayed. You will still have multiple coats to spray as mentioned previously, with sanding/leveling inbetween coats. A good worklight that can be moved and adjusted will help, using it from the side to highlight imperfections in the surface currently being worked on.

Best regards,

John
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post #17 of 35 Old 05-30-2011, 11:11 PM - Thread Starter
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Thanks guys! You've been a big help!

In terms of LFE, size does matter!
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post #18 of 35 Old 05-31-2011, 03:45 AM
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Quote:
Originally Posted by Favelle View Post

So is there a special kind of Bondo for wood? Or can I go to NAPA and just get automobile Bondo?

There are different "grades" of bondo. For most applications, the normal cheap stuff is fine.

BUt you can get a "finer" grade that will have less "holes" in it. It is for finer auto body work, and would be the best choice for a piano finish.

It is a little bit more expensive.

Jjust be sure to keep your applicators clean and smooth on the edges.

If you don't need to match the wood (like in a stain grade finish) then bondo is the best/fastest/cheapest solution.

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post #19 of 35 Old 05-31-2011, 03:51 AM
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It would be easier to glue on a layer of 1/4" or 1/2" MDF over your enclosure first rather than try and fill all the screw holes.
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post #20 of 35 Old 05-31-2011, 05:21 AM
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There are very nice laminates that simulate a piano finish. You would be limited to square corners but someone with limited experience would be more likely to be successful.

T6

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http://www.avsforum.com/avs-vb/showt...1#post19489740
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post #21 of 35 Old 05-31-2011, 09:00 AM
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Quote:
Originally Posted by Fatawan View Post

It would be easier to glue on a layer of 1/4" or 1/2" MDF over your enclosure first rather than try and fill all the screw holes.

+1, The more time I spend filling in holes, seams and smoothing out all types of ply wood the more I think a thin layer of MDF will save hours and hours.

FWIW, I hate bondo and I instead use Miniwax wood filler. It seems to mix with the hardener better and can be applied easily. Bondo never wants to play nice for me.


For really small spots. Glazed putty found at an automotive shop comes in a tube no mixing needed just squeeze and apply. That stuff rules for finishing.

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post #22 of 35 Old 05-31-2011, 12:48 PM
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Lots of bondo and sanding and bondo and sanding and bondo... you get the idea. Bondo the whole surface lightly then sand down, you'll start to see where the dips and bends are in the wood. You'll have to do this over and over until you get a perfectly smooth face for each side. If you just fill the holes and sand it down then paint it wont turn out like you wanted. Don't forget primer/blocker
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post #23 of 35 Old 05-31-2011, 04:51 PM
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This is my opinion from a guy who use's body filler every day for the last 15 years.

Start with the regular ol bondo, fill all your holes as best you can as well as the seams (your going to have to go over a bunch of screw holes and seams again to make them perfect) Then use the light weight metal filler for your second coat. It sands easier, and is about half the density as regular bondo. It will flow out to fill in imperfections. Thats the way to do it. DO NOT START OUT WITH THE LIGHTWEIGHT FILLER FIRST! you WILL be making yourself much more work, I promise you that. There are no air bubbles in bondo if you mix it properly on a clean surface with the proper amount of hardener. Pinholes are caused by dirt, improper mixture and improper hardener amounts. You have to kneed in the hardener until it's completely uniform in color. If you do get some air trapped or dirt, the light weight filler will fill the pinholes with a light coat and an easy sand off.
Then go to your primers and do as what every ones else is stating. prime, sand, prime sand etc.
I've done well over 50 subs boxes for myself as well as customers, as well as speakers, and all sorts of audio gear. For me, I have all the air tools to make it a breeze to do piano black, as well as spray booth and everything you'd need at your disposal.

If it's good enough for a 2011 ZR1 vette, then it's good enough for a freaking sub box lol

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post #24 of 35 Old 05-31-2011, 04:56 PM
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Could you give me a link to a brand of "light weight metal filler"?? Sounds like a product I need to buy tommorrow for my new waveguide and subwoofer boxes finish.

I also still looking for the best primer in a rattle can.

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post #25 of 35 Old 05-31-2011, 05:09 PM
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yup, this is the stuff I use at work and when doing boxes :

this is what I'd use for full weight filler : http://www.eastwood.com/evercoat-rag...er-gallon.html

as this for the lightweight : http://www.eastwood.com/metal-glaze-...mp-bottle.html

Both are pretty much the cream of the crop in autobody. I've used pretty much everything that is made that would be sold in a supply store and these 2 are used at pretty much every shop I've ever worked at because they work great.

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post #26 of 35 Old 05-31-2011, 05:09 PM
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Quote:


Layering a few coats of epoxy like the Abatron product will help provide a harder, sealed, and smoother base(if sanded with leveling blocks and pads) for the primer/paint/clearcoats to be sprayed.

I took one of those counter top high gloss epoxy boxes and mixed/poured it over each side of my new subwoofer box to create a very smooth surface. With the 90+ deg heat here it hardened in about 4 hours, I did 2 sides each day. Great way to sealed/smooth the birch ply.

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post #27 of 35 Old 05-31-2011, 05:11 PM
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Quote:
Originally Posted by penngray View Post

Could you give me a link to a brand of "light weight metal filler"?? Sounds like a product I need to buy tommorrow for my new waveguide and subwoofer boxes finish.

I also still looking for the best primer in a rattle can.


there isn't a best in a rattle can, they are all crap compared to even a crappy 2 part system like U-pol.

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post #28 of 35 Old 05-31-2011, 05:13 PM
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Penn, I have a half decent napa spray gun I'll never use since Sata gave me 6 new ones for free . It's a 1.7 tip, perfect for thick primer. If you want it, I'll send it to you for nothing.

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post #29 of 35 Old 05-31-2011, 05:16 PM
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Quote:
Originally Posted by N8DOGG View Post

there isn't a best in a rattle can, they are all crap compared to even a crappy 2 part system like U-pol.

I understand that

Quote:
Originally Posted by N8DOGG View Post

Penn, I have a half decent napa spray gun I'll never use since Sata gave me 6 new ones for free . It's a 1.7 tip, perfect for thick primer. If you want it, I'll send it to you for nothing.

Thank you very much! What compressor/spray system do I need to buy for that though?

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post #30 of 35 Old 05-31-2011, 05:24 PM
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Quote:
Originally Posted by penngray View Post

I understand that



Thank you very much! What compressor/spray system do I need to buy for that though?

pretty much anything will work. The bigger the compressor the less time it will take to fill it back up. I've used those small 3 gallon ones at a low pressure and you will have to stop to let the comp catch up but it will still work. The only thing you may need to buy will be hose fitting, as the one I use at work is a High flow but anything will work fine. I'll get it cleaned up at work tomorrow and ship it out before the weekend. PM me your address.

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