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Build II - Paradox MJ5 - New design!

#1,122
Today I ordered sanding paper ranging from 400 dry and then 800 wet to 2000 wet for sanding the finish. I plan to use the 400 dry first to get the current layers level before continuing. The wet paper will be used to get the finish ready for polishing.

The fifth layer now is cured well enough for sanding (just have to wait 'till the paper arrives) and looks like this:

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As you can see, the top is more wavy than I expected, even more because the first two layers where rather smooth actually. Maybe it's because the layer dries a bit fast at 38% humidity in my heated workshop these days (subzero temperatures outside).

I hope I can get it level well enough, because if it won't level out now, the next layers will I guess aggravate the effect.

The rest of the bass looks okay. The back is smooth although you can still feel the grain (which I like) because I didn't use grain filler as I planned to go for a thin satin finish and changed my plans halfway due to tips to use a gloss finish, sanded and polished afterwards. I can leave the back of the bass like this if I want, I think the result is good as is. The back of the neck is pretty smooth, but has a few dust particles in there and certainly needs polishing for a good feel and playability.

All in all, it's quite exciting because it's a crucial part of building and the finisih can still make this bass awesome (as I think the wood working turned out up until finishing) or get horrible, if I screw up the finish.... kind of whished, with what I know now, that I just oiled it and be done with it, but on the other hand I learned a lot and the reds' killing.

I'll keep you posted!
 
#1,124
Prostheta said:
Don't dry sand. The debris will load up the paper and it will be too aggressive. I would perhaps start with 600 too.
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600 will cut to slow for this point in the finish, and wet sanding at this stage will hide the low spots, and make it hard to see if you are in danger of cutting through the finish. I never start wet sanding until after I put on my final coats.

When the paper loads up a blast with an air hose is usually enough to unload it.
 
#1,125
Prostheta said:
Don't dry sand. The debris will load up the paper and it will be too aggressive. I would perhaps start with 600 too.
Click to expand...

Hopkins said:
600 will cut to slow for this point in the finish, and wet sanding at this stage will hide the low spots, and make it hard to see if you are in danger of cutting through the finish. I never start wet sanding until after I put on my final coats.

When the paper loads up a blast with an air hose is usually enough to unload it.
Click to expand...

Now, who should I believe? :D

I am with Hopkins on the too slow cut of the 600, since my finish is rather rough (opposed to what I think is normal after 5 layers of finish, normally probably clear nitro). I tried wet sanding with 600 on the neck and on the drips between the fourth and fifth coat, it worked but went a bit slow.

Ordered both, will probably start safe with 600 dry and go to 400 dry if I feel is necessary. Right?
 
#1,126
Not to confuse you any more Rob, but personally I wouldn't try to sand anything other than visible surface lint or other minor spot imperfections away at this point. :hiding:

Based on the pictures - to my eyes - the waves and uneveness along the top that you are tempted to fix may result in some unpleasant tearout of the surrounding varnish which may still be gummy/tacky, or worse, opening up of a witness line.

I wouldn't feel comfortable that there are enough layers on there to safely try to begin actually "leveling" - you really want a number of coats on there, with plenty of time for them to cure. By and large you'll be able to get out the waves with additional topcoats of varnish applied.

Lonnybass
 
#1,130
I have a few small witness lines on the side on the treble part of the body (underside) right in the curve where you put the bass on your leg. This is where I fixed an ugly very shallow but wide drip from the fourth layer and didn't dare to sand through completely. The fifth layer did hide them when wet, but now it's dry you can (barely) see them in the right light. Not a bad spot for such a blemish though, I don't think anyone will ever see it there. About half of the drips I fixed went out perfectly well and are completely invisible. In two spots, I cut through the complete gloss finish and hit the wood around where the first satin layer sealed the wood. I got some witness lines in there too, but sanded well enough to blend the multiple layers and I'm having a hard time finding them right now, after applying another layer, but they should be there.

Witness lines on the top would ruin the bass. Don't want that.

If you guys think I can safely add more layers without losing the ability to completely flatten the top later, I feel I just need to go on putting coats on there. It's the fact that I find the result too wavy, that I think more layers would make the surface even more varying in height. True? Or not?

I feel that the back (ash) does need no polishing. Looks good as is. The grain shows some valleys in the finish. Doesn't look bad, really. But if I start sanding it, I would certainly create witness lines around them or go through the finish. Don't want to put a lot more coats on there now it looks okay. Or would more coats even it out, even in the parts where the grain is??

If anybody wants to see a more exposing picture, I can try to make one tomorrow.
 
#1,131
Lonny,
I wasn't really suggesting doing a full level sanding just yet. Just a light sanding to knock the tops of the high spots down. I don't think witness lines should be of any concern at the moment as they will disappear under the next coats.

If he started knocking down the high spots lightly right now, it will slowly start to level out through the finishing process, which will save quite a bit of time down the road. There will have to be at least one more coat applied after the final level sanding anyway, to get rid of any witness lines that appear, which there most likely will be.
 
#1,132
Hopkins said:
There will have to be at least one more coat applied after the final level sanding anyway, to get rid of any witness lines that appear, which there most likely will be.
Click to expand...

So you say I would have to do one more full coat after the complete level sanding and polish afterwards? Or sand completely level, coat, another sanding round and then polishing?

I'm at 5 (thick) coats of PU varnish now. What do you reckon is a nice total? Would 6 be enough? Or eight? Seems so thick already..
 
#1,133
roberthabraken said:
So you say I would have to do one more full coat after the complete level sanding and polish afterwards? Or sand completely level, coat, another sanding round and then polishing?

I'm at 5 (thick) coats of PU varnish now. What do you reckon is a nice total? Would 6 be enough? Or eight? Seems so thick already..
Click to expand...

Yes, you will have to do one more coat after its level, unless you can manage to get it level with no witness lines.

Its not a big deal really, after your level sanding apply one more coat, then sand and polish that coat starting at about 800 grit, working up to 2000.

Getting the finish level usually means sanding through a couple of layers on the high spots leaving the low spots there. This pretty much means you will have witness lines that will require another coat to cover up. This doesn't happen with a nitro lacquer because each coat burns into the previous.
 
#1,134
Hopkins said:
Lonny,
I wasn't really suggesting doing a full level sanding just yet. Just a light sanding to knock the tops of the high spots down. I don't think witness lines should be of any concern at the moment as they will disappear under the next coats.

If he started knocking down the high spots lightly right now, it will slowly start to level out through the finishing process, which will save quite a bit of time down the road. There will have to be at least one more coat applied after the final level sanding anyway, to get rid of any witness lines that appear, which there most likely will be.
Click to expand...

Completely agree! Emphasis on light sanding :cool:

Lonnybass
 
#1,135
Got some shop time again tonight: the sixth layer of varnish is on :smug:.

When I came back at the shop, I noticed the waviness on the top wasn't as bad as I 'remembered' and it actually looked quite doable to sand flat. So that made me feel better.

Next I decided to dry sand the back of the neck with 600 grit paper, because there were a few dust particles present in the last layer and the finish didn't feel smooth. This was also a test for the top, which I decided to leave untouched before varnishing this time though. I actually did get the back of the neck rather level, say 80%, very quickly. I indeed got some witness lines, but they disappeared when cleaning with naptha, that's a good sign. This whole process gained me some confidence again. I also did some spot repairs on the body.

So I put on the sixth layer of varnish. The witness lines seem to disappear, the finish seems to smoothen out well at first sight. Now let's wait for 24 hours to see how it turns out.


Oh, and I also fixed the problem of having to wait for three weeks while the varnish cures: I recently got a vision of my next build, a short scale six string with a hollow body (yeah... it's a guitar :hiding:).
Got the sketches ready, working out the specs, to be starting with the final drawings very soon :hyper:.
 
#1,138
wraub said:
AWWRIGHT! A new build thread... ;)

Glad the finishing is going well, really looking forward to the completion of this.
Probably not as much as you, though...

wraub
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Cool isn't it? I'm really excited about the idea and the build, but being a guitar, its build thread won't be on TB alas.
And I do indeed look forward to the completion of this build more than you can imagine ;).

Lonnybass said:
You're doing great work Rob. Finishing is often three steps forward and one step back (or sideways). Can't wait to see some more pictures. Excited things are working out so well on the bass!

Lonnybass
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Well, I got my confidence back and my hopes up, whether it'll turn out okay or not is still like Schrödinger's cat (pun intended towards this bass' name :smug:).
 
#1,139
roberthabraken said:
Cool isn't it? I'm really excited about the idea and the build, but being a guitar, its build thread won't be on TB alas.
And I do indeed look forward to the completion of this build more than you can imagine ;).



Well, I got my confidence back and my hopes up, whether it'll turn out okay or not is still like Schrödinger's cat (pun intended towards this bass' name :smug:).
Click to expand...


Is there some rule that TB builds must only be basses?

As for Herr Schrodinger... If you just don't look at the bass, it'll be perfect.
:D

wraub
 

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