Finish sanding schedule..

[nnickusa]

OK, I'm doing my finish sanding, as imlpied by the title.....

I've got a pretty good pore-fill, which I did with shellac and sand paper. Tried the pumice--what a pain--Oh yeah, 1kg LMI Pumice for sale....

My question: How far do you all go with sanding back for a lacquer finish? I've got the Mirotone 3220 HG, and plan to spray soon.... I've rubbed to 280, and have grits at 320, 400, 600, 800, 1000, 1200....

Michael Connor said he only goes to 180 when I was round there the other week....If I recall properly

I'm hesitant to stop where I'm at, mostly because when I used to paint cars with lacquer as a kid, I rubbed back to AT LEAST 600....and then rubbed back again between every 2nd or 3rd coat....

And I think the blackwood on this guitar deserves a really nice finish..

Thanks for any advice...

[graham mcdonald]

280 grit should be fine. Worthwhile spraying some water on the soundboard. That will show up any scratches on the soundboard you may have missed and also any glue that may have oozed out and soaked in when gluing the bindings. That shows up under lacquer annoyingly. I do that before pore filling the back and sides. There are those who maintain that sanding hardwoods past 240 or so is just polishing the wood and actually making it harder for the lacquer to adhere. Little scratches that can't really be seen on the sides and back are much more noticeable on spruce or cedar

cheers

graham

[liam_fnq]

See Allen's tutorial. His results speak for themselves.

[nnickusa]

Yeah, thanks Liam.

i've pored over the entire tutorials section. It's a rich resource, but thought I'd see what anyone else does. My real reason is that on the top, I can still see faint traces of the sanding pattern, and wonder how much they will show up.

French polishing the last one showed up the flaws in my preparation, and i'm looking for greater insight into preventing such an occurence.

One thing that happened with this ione is that I laid down a coat of shellac on the top, and ended up with great big blotchy patches with white edges. I've taken all that off, but wonder if I'm ready to proceed....

Ah well, time will tell...

[Tod Gilding]

Nick I alway's finish with OOOO Steel wool it seems to polish the wood and I havn't had a problem

[simonm]

I met a now retired builder here in Germany who said he never used finer than 220. Given that there are a number of different grading systems, it may not be the same 220 as you have in Oz.

[Kim]

Nick I alway's finish with OOOO Steel wool it seems to polish the wood and I havn't had a problem

I use to do that also Tod but was warned off by a mate who ran a solid wood focused cabinet maker/joinery shop. Very good tradie and really, really, nice work. His thoughts were that its OK to use 0000 wool if your doing a resto where pores will be left open and its a rubbed finish that is 'in' the wood and the surface will still get plenty of air, but he suggested it was too fine for good long term adhesion when using a film finish because it burnishes the surface too smooth, and with expansion and contraction through the seasons, that its only a matter of time before problem areas develop.

The other point he made was that using steel wool carries issues with lite coloured wood, that no matter how careful you are its near impossible to remove every tiny bit of fine steel wool that may be caught in the fibres of the wood. That may not be much of an issue at first but given 'all' finishes are hygroscopic to some extent, he suggested that staining can become an issue as the steel wool fibres begin to oxidise and colour spreads into the wood and finish.

Have I seen this happen for myself?? No. All the projects I have done with wool back in the early days were darker woods i.e; jarrah, fumed oak etc and it was all open pore hand rubbed 50/50 oil and urethane mix and it still looks fine...but the truth is I have no reason whatsoever to doubt Darby's word because its knowing the stuff which others overlook that made his craftsmanship such a draw card to his customers...That said, did he ever ramp it up and bullshit over a beer with his mates?.................


Absolutely!!!

Cheers

Kim

[nnickusa]

OK . I'll finish up the few other bits, and give her one more good going over with 280, and let it lie in the laps of the gods...

The top is what mostly concerns me, as the back and sides are busy enough to hide any little marks, but the top is looking really good now that I got rid of that aweful staining---no idea where that came from...any suggestions?

It was a wee bit cool, and may have been drizzling, but I don't remember...first coat on the top looked fantastic, second on the top---disaster....back and sides fine all the way thru three coats

[Bob Connor]

I only sand to 240.

My first sprayed coat is my "exploratory" coat. Just to give me a look at what needs drop filling and resanding and where I I've left glue (if I'm using Titebond.)

I remember a quote from Rick Turner a few years back, something to the effect that anyone who sands to more than 240 is a wanker .
Not wanting to be known as a wanker I've always adhered to his advice. (no pun intended)

I think that you may run into adhesion problems down the track if you sand to any more that 300. You do need some "tooth" with a laquer finish.

[Tod Gilding]

Thanks For That Info Kim, looks like some changes for myself.

[Allen]

Never finer than P320 on any wood Nick as you will start to loose adhesion with lacquer. And I only go there on a softwood top to take out any really fine scratches that might show up under gloss like that dark Western Red Cedar top on that Bass Uke in the Gallery. That is in conjunction with a light wipe with a damp rag to raise the grain. Done a couple of times until its really smooth.

On hardwood it's either P180 if the wood is quite hard and P240 if it's a bit softer.

You need to get a bit of build on the instrument before you cut back with any sandpaper. I wouldn't ever cut something back unless it was a very large piece of dust or a run until I got several coats on with the way I thin my clear.

If the instrument rests overnight, then you must abrade the surface for good adhesion if using Mirotone 3220.

Use P320 or P400 dry to cut back between your 1st and 2nd spray sessions. That way you can see what's going on. Low spots with still be shiny. If you try wet rubbing you've got no idea until you clean everything up and dry it off. Stay away from edges and whatever you do....DO NOT CUT THROUGH!

[kiwigeo]

The only time when you should go finer than 320 grit is when you're polishing a turd.

[nnickusa]

Ok, I'll stay at 280, since I'm there. I've done a few damp rag/sanding sessions, and reckon it looks pretty sweet. When I wipe it, it looks really smooth, so I think I've got the worst out of the top....I piked today on the spraying, but am gonna take the gun down to try a few runs with water and see how it goes. it's a new gun, and I haven't sprayed in many years, so I'll not jump right into spraying the guitar, I think....

It's supposed to stay clear, warm and dry this week, so I ought to have plenty of time.

Bob, what is the issue with Titebond? That's what I'm using so I don't want any rude shocks...

[rocket]

Martin,, you know full well that you can't polish a turd, just as you can't make strawberry jam out of pig sh.t.
Rod.

[nnickusa]

Rod,

I've seen some truly mind-boggling things made out of "cow-pies" and "buffalo chips".....

I think one might have to be from Texas or Oklahoma to truly appreciate these items, but people do do strange things..

[Nick]

Martin,, you know full well that you can't polish a turd, just as you can't make strawberry jam out of pig sh.t.
Rod.

The guys at Mythbusters managed to actually polish up a turd in one episode but I seem to remember it could only be "poo of lion", nothing else would hold together & take a shine! And remind me not to have toast if I'm ever at your place!

[Nick]

youtu.be/

[Allen]

Bob, what is the issue with Titebond? That's what I'm using so I don't want any rude shocks...

PVA's are not invisible under finish, and will end up much lighter than wood not contaminated with it. So if your glue clean up and prep afterwards was not meticulous, you will be in for some disappointment. You should be able to spot any potential problem areas if you have wiped down the wood with a damp cloth. They do show up that way.

[Bob Connor]

What Al said.

I use z-poxy for grain filling so I usually see any glue before I get to the finishing schedule.

If you don't sand it all off it will stand out like dog's balls under finish though.

Regards

[auscab]

One thing that happened with this ione is that I laid down a coat of shellac on the top, and ended up with great big blotchy patches with white edges. I've taken all that off,

Blooming is one name for it.or the main one used
Close the doors and windows and heat the room. Or heat the shellac like it was HHG ,shellac container in a tub of hot water.
I bought some cheaper metho a while back and with the weather lately I have been getting it a bit. I was doing some drawer fronts last week and it started to show up right across the whole surface. I put it in front of the heater and half an hour later it was gone. I have polished over mild cases of it and sealed it in because I did not notice it and have not been able to get rid of it without rubbing right back

How much for the Pumice ?

I've been playing with silica mixed with a oil based sanding sealer and a little colour for grain filling with the credit card method . Under shellac. All my tests have been on US white Oak , pretty darn good too.
I bet the pumice used that way would be worth a try.

[nnickusa]

Hey Rob,

$5. Plus post. Ought to go in a small satchel, I'll check the cost. It's a pound not a kilo. $7.05 on LMI, plus your first born child for postage

[auscab]

I'll take it thanks. Let's pm details.

[kiwigeo]

Hey Rob,

$5. Plus post. Ought to go in a small satchel, I'll check the cost. It's a pound not a kilo. $7.05 on LMI, plus your first born child for postage

Pumice can be sourced here in Australia....alot of places sell Liberon brand pumice.

[kiwigeo]

The guys at Mythbusters managed to actually polish up a turd in one episode but I seem to remember it could only be "poo of lion", nothing else would hold together & take a shine! And remind me not to have toast if I'm ever at your place!

For some reason right now I'm thinking of Nick polishing his lime green Commodore.....

[Ormsby Guitars]

The only time when you should go finer than 320 grit is when you're polishing a turd.

Obviously I must be polishing turds...

I end at 400 grit. Anything coarser shows up under stain.

400 between coats when needed, and foam backed 600 before the final coat, then 2000 straight up before buffing.