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Sanding Grain Filler On Stained Body....


GregA

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Hi All,

Here is the deal. I am currently in the finishing stages of my Les Paul build. (after 3 and a half years!) Although I am doing all the actually work, I have accessed the help of a professional luthier to ensure that I don't screw it up too bad! (this guy has done work for many professional players in our area)

His sequence of events in regard to grain filling is somewhat different from what I have read about and would like a bit of advice....

We have stained the mahogany back and neck (a beautiful dark cherry) and then sprayed a single wet coat of clear lacquer. We will then be grainfilling with an oil based filler, using a credit card to remove the excess, and letting it sit for a day. Then we will be carefully sanding any excess filler. Now, I know this is significantly different from the accepted method of either filling before staining or wiping the grain filler off with mineral spirits before it completely sets up. At this stage though, I have nothing but confidence with this guys knowledge and approach but have just one question. Clearly this creates a massive issue in regard to sanding through the lacquer into the stained wood. Has anyone done this and just how difficult is it to pull off without sand throughs? I am will to go inch by inch slowly to ensure I am "careful" but was curious as to just how hard this is going to be. (clearly any edge area is going to be particularly picky) Also, in the event of a sand through, what are my options? I have plenty of the dye left over I used for the body. Is there any chance of recovery if things go a little sideways?

Anyone pull this off before? Basically I am nervous as hell (as I am sure you can tell) and would just like some opinions!

Thanks all!

I will be posting pics when I am FINALLY done!

Greg A

Edited by GregA
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We have stained the mahogany back and neck (a beautiful dark cherry) and then sprayed a single wet coat of clear lacquer. We will then be grainfilling with an oil based filler, using a credit card to remove the excess, and letting it sit for a day. Then we will be carefully sanding any excess filler.

Yep that sounds right to me. You dont really need to be worried about sand throughs. That sealer is hard as a bugger! you'll know when you've done enough B) . Just sand flat , it's really easy to do and I dont think you'll have any problems. Espicially with an experienced helper :D

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We have stained the mahogany back and neck (a beautiful dark cherry) and then sprayed a single wet coat of clear lacquer. We will then be grainfilling with an oil based filler, using a credit card to remove the excess, and letting it sit for a day. Then we will be carefully sanding any excess filler.

Yep that sounds right to me. You dont really need to be worried about sand throughs. That sealer is hard as a bugger! you'll know when you've done enough B) . Just sand flat , it's really easy to do and I dont think you'll have any problems. Espicially with an experienced helper :D

Good afternoon folks,

I'm a part time picker who spent 25 years as a furniture maker and finisher. The first thing tht I learned is that is no one right way to do any of this stuff just a lot of basic rules to follow.

I wouldn't have used lacquer as an undercoat, I would have used lacquer based sanding sealer. Just my way of doing it. As long as your filler will bite to the laquer you should be okay. Be really careful sanding cause if you cut through it will show from across the room with a dark stain. You can take off the filler with solvent (turpentine or mineral spirits) and burlap and avoid the cut through problem even if it's dry. You just have to let it re-dry for a day before you re-coat it. Doing things the way you are doing them avoids a lot of problems that you have when you fill, stain and seal.

I have always hated working with grain filler. Nasty gooey crap, but it's the only way to get that mirror finish.

If you do sand remember to still wipe it down really well with a solvent. I've had a lot of jobs where I've had to go back. After I hit the first coat of top coat I find all the smugy places that I didn't get all of the filler off, but were camoflaged by the sanding.

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No gutterballs with this group! All the above sounds like the path to a beautiful finish. Specially the slow, careful part. BTW, you are at the part of finishing that makes me VERY nervous. After dozens of new and redos, I still hold my breath.

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Thanks for the input everyone!

If I do happen to sand through to the colour coat, what are my options? I have more of the base colour dye....could I not just re-stain it, then spray clear? It probably wouldn't be perfect but I imagine it would at least lessen the "eyesore" effect somewhat.

Thanks again,

Greg

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Alright..........here is the sad update! Information needed!

After letting our oilbased filler sit for a couple days we gently went at it with 400 grit sandpaper on the back.

Here is what happened! No matter how lightly we went at it with the sandpaper, if lightened the tone dramatically. It is now clear that sanding a stained mahogany back with just one coat of lacquer to seal the stain doesn't work if you plan on sanding...

So...I am in the process of sanding down the back and neck to the mahogany. Luckily I still have the dye that I originally used so getting back to where I was will not be a complete hassle.

Now.....so here is plan B:

1. Re-dye the back. (dry for a day)

2. Spray a wash coat of clear lacquer. (dry for a day)

3. Brush on the Oil Based grain filler.

Now here is the information that I desperately need clarification on...

1. When applying the grain filler how long should I wait untill I wipe the excess of the "field" of the wood? (I'm not touching it with sandpaper again) The Doctor mentioned that it can be done the next day no problem but I was wondering if this is different for oil-based filler. I seems like this stuff hardens like concrete over a day or two and am concerned about waiting too long.

2. What should I use to wipe off the oil based filler? I need something that will not effect the lacquer.

Thanks for all the help guys....

Greg

Edited by GregA
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Thanks fotr the compliment guys.

Here's what I would do.

1) make sure that everything is sanded perfectly. Any scratches will show.

2) Stain the puppy. Let it dry. Oil based stain should go 24 hours in a warm dry place. This is Minwax type stuff. If you're using a hotter solvent stain like Campbells's give it a couple of hours. To be safe let it sit overnight.

3) Shoot a "dust" coat over the whole thing and see what it does. I'd reccomend sanding sealer if you've got it. If you're going too fast it will go white on you so do the back first. If it looks good go ahead and shoot a very light coat on the whole thing. Wait until it is dry to touch and shoot a decent coat. Sand this out with 220 grit sandpaper. Use the grey kind cause it has a lubricating agent that keeps it from clogging.

4)Wipe it off with a clean uncontaminated dry rag..

5)Look it over and make sure you didn't cut through anywhere.

If you did don't worry, just reshoot it, and repeat three and four.

6) Wipe the nasty gooey gunk all over and leave a good skin on the body. Let it flash, this means let it haze over. This doesn't usually take too long. Like minutes not hours. Take some burlap and wipe against the grain Just take off the top not what's in the pores. You'll get a feel for how hard and long to go at it with a little experience. Look at it in reallly good light and make sure you haven't pulled too much off. If you have wait overnight and recoat it. When you hold it up to the light you shouldn't be able to see any dips down ino the pores.

7) Let if set up overnight and tomorrow when it has started to petrify wet a piece of burlap with solvent (use wht the can recommends as a thinner) and wipe with the grain.

Get it really clean, I just rushed one and had to restrip it cause it ws cloudy when I top coated it.

8) Shoot a sealer coat. Again, I'd use ssanding sealer. Let it dry and shoot another.

9) look at it. If it looks like a decent finish then go to your top coat. If it looks like it needs more finish then hit itt again with the sealer. Remember to sand lightly and wipe down between coats.

It is easier and faster to build with sealer than lacquer.Sanding sealer has stearates in it which make it less difficult to work with but softer.

10) when the sealer looks like a decently finshed ax go to your lacquer.

11) You should have to do a minimum of sanding in between coats. Just need to take care of any Murphy's that fall out of the air into your now mirror like finish.Keep building until you're happy with it. If you do a decent job of building with sealer you can probably get a No1 job with less than ten coats depending on how much you thin it out when shooting.

12) If you are an **** retentive like me give it about a couple of weeks and go at it with a buffer and polishing compound. 3M Finess it or Mauquire's are the ticket and what the pros use. If you've been very good you can get away with not rubbing it out, but it really does make it turn ito a slippery devil when you do.

Take your time. Any effort to rush things quarrantees a screwed up mess. It does take a lot of clock time, but not that much work time. Lots of wait till tomorrow. Just be glad you're not doing a twelve foot by four foot conference table.

A really good reference book is Bob Flexner's finishing book.

I learned my chops from Bobberit Jackson, who was one of the best finishers who ever walked the planet, and left us this year before the SOB could answer all of MY questions.

I hope this isn't flogging a dead horse. Feel free to disagree with me because ther are lots of differing opinions on this stuff.

Happy finishing.

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Thanks Doc!

You have been a huge help!

I have a couple small questions. After you wipe with clean burlap, I assume there will still be a lot of haze. I have heard of people actually using a rag with mineral spirits to wipe off the excess after about an hour or so. So basically doing the procedure before it full sets up overnight. Any opinons on this? I guess the biggest problem would be pulling the fill out of the pores but I assume you could just let it sit overnight then go at it again the next day. My thoughts are that this would ensure that the "field" of the wood is filler free in the end.

Also, the filler we are using is the actual stuff that Gibson used in the 90's. There is no label at all. We used naptha to thin it. Would that do to wipe the pore filler off?

I apologize for so many questions and truly appreciate your insight.

Thanks again,

Greg

Edited by GregA
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I would wait for a little while after I'd wiped the thing down the first time to get the leftovers off. Rub it with your finger and see if it's almost completely dry. That's when you go at it.

The nice thing about using burlap is that it is aggressive on the filler but soft enough to not mess up the finish.

If naptha is working for you, it should be safe as long as you don't flood it.

This is not an exact science. If you wait too long the stuff, as you have discovered, petrifies and you wind up working yourself to death. If you do it too fast or aggressively you pull out the filler. Just take your time and use really good light so you can judge what you're doing as you do it.

To really see if you have gotten all of the haze off take a clean rag, wet it down with denatured alcohol and wipe a healthy wet coat on. It will make it look like it will with a coat of finish but should not affect either the filler or the finish. Look at it in the light and get down and bounce the light off of the surface. You should be able to see any problem areas.

**It is always better to take off too much filler than to leave any excess on.**

The whole reason to use a pate filler is to keep from having to use finish to fill the little pores. In time, if you just used laquer it would dry and shrink down. You want to just minimize the settling by putting something that dries hard as a rock in there. If you look at an old finish under a magnifying glass you will see that the grain has eventually shrunk in some no matter how good the finisher was. The reasons that polyester gets used are 1) it builds really fast and 2) it doesn't shrink much, so the filler stage isn't as critical. IMHO it still looks like plastic crap. Nothing beast a nitro lacquer finish.

Post some pictures so we can see the end results! Good luck and happy trails.

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