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#196
11-15-2016, 04:40 PM
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I've recently tried three different approaches to pore filling.
The first is the traditional approach I've been using for 30 years. It is a solvent/oil-based paste filler. It is thinned with naptha or mineral spirits until it is about the consistency of natural peanut butter. It is also the color of peanut butter and can be tinted with tempera paints, universal tint-alls or similar. After 5 minutes, it flashes off to lose its sheen and is then whipped off across the grain with steel wool or burlap. Usually, one application will fill the grain on many woods. The second is an epoxy-like acrylic, applied much like epoxy-based filler - rubbed on, squeegee off. It seems to take numerous repeated applications to fully fill the pours. Weird stuff. It is a milky liquid that dries to a transparent hard plastic film in about 5 minutes or less. A pain to sand flat, but scrapes very well. I don't like that it takes so many applications, but I do like that it is absolutely transparent and fills gaps and holes as well as the grain, invisibly. The third is the old fashioned colored pumice or plaster of Paris with a French polish. Easy to obtain, simple to apply, but does take many applications. I made the mistake of using un-colored pumice on dark wood and ended up with the pores full of white powder: not the look I wanted. Sanded the filler off, colored it with natural pigments and re-filled. All of them work. It's just a matter of preference and availability of materials. For a surface finish - as opposed to a penetrating finish - for a guitar finish, I wouldn't like the look or feel of open-pored woods that aren't filled. Just me. It isn't particularly difficult to fill the pores, nor is it particularly difficult to find materials to do it. The paste "wood filler" than many home building stores sell for filling nail holes is not the right stuff for this job. 
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#197
11-15-2016, 05:21 PM
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Charles certainly knows volumes more about pore filling than I do, but it sounds like your location may be a sourcing problem. My last build was also walnut and bloodwood. I took a recommendation from this site and used egg whites as a filler. It did take several applications, sanding lightly between slurry coats and using a thick rubber spreader. It dries fast, so 3 or 4 coats a day are easy. I did use a Tru-oil finish so I can't speak to how it would look in high gloss. I'm very happy with the results I achieved. Something to consider.
__________________
BradHall _____________________
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#198
11-16-2016, 06:24 AM
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When the finish guy says he doesn't fill pores because it's obvious and looks terrible, does he mean he achieves gloss without filling by having the finish fill the pores? I've read that you can get away with having lacquer sealer fill pores in walnut if you're willing to sand back a lot between coats.
I conducted a test using thinned MAS Low Viscosity Epoxy as a filler/sealer. Using a small dense foam roller, I applied the Epoxy thinned 10% with denatured alcohol. It leveled pretty nicely and once cured, I sanded back to the wood being careful not to sand so far back that I exposed new unfilled pores. Then I applied a second coat, again using a roller. This time, after curing, I only sanded enough to level and smooth. After top coating, it looked pretty good. You do need to be careful though because if you let it build too much, it starts to get a plasticky look. The MAS Epoxy thinned with DNA is pretty thin though and doesn't seem to build too much. Using the roller makes it more or less like applying paint.
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#199
11-16-2016, 02:34 PM
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will Amazon ship pore filler from Germany to Switzerland?
https://www.amazon.de/s/ref=nb_sb_no...3Agrain+filler
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#200
11-16-2016, 03:21 PM
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Quote:
So I spoke to the guy who will be doing my spraying again today, and his technique is as follows. 1. Sand wood to required grits, he normally suggested 150, (but i'm going to go with Charles' recommendation and go to 220 on the back and sides and probably 400 on the top) 2. add first coat of lacquer, once thats on, sand back almost all the lacquer layer, basically using that first layer as a pore filling layer, using 180 grit. 3. add layer 2 of lacquer. 4. sand this layer using 240 so that the next layer has something to stick to 5. add layer 3 of lacquer, the final layer 6. sand and polish. I'm not sure what grit to sand to after the last layer goes on, i'm not sure how much sanding to do at that point, and wondering if I should just either a) wet sand at 1200 or so, or just go straight to an angle grinder mounted buffing/polishing machine.
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#201
11-16-2016, 03:29 PM
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Bummer about the shipping form Germany... Oh Well.
I've never polished a finish to gloss using a machine. For my untrained hand, it's just too risky. Doing it by hand affords a lot more control and as I like to say, it allows me to make mistakes more slowly. If I'm starting with a decent spray job, I wet sand using 1000, then use Micro-Mesh, going through each grit. The final grit in MicroMesh is 15,000, so it's pretty glossy by then, but I follow that with a car polish called Meguiar's Show Car Glaze. After that, it's like glass.
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#202
11-16-2016, 03:50 PM
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Have you seen examples of his finished finishing work?
If he's using any sort of typical sprayed lacquer, three coats of lacquer, two of which are sanded back, will not fill the pores and will not give you anything approximating a mirror gloss. More than likely, that thin, you'll sand through the finish to bare wood in more than one place attempting to level the finish. At best, you can expect a shiny-ish, pitted surface. I'm still puzzled by his comments regarding filled pores being "always obvious and looks terrible". I'd recommend looking carefully at his finished work to evaluate if it is the finish you want.
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#203
11-16-2016, 05:51 PM
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I'm with Charles all the way here wondering if your man has the right experience for finishing guitars.
If a pore filler isn't used then spraying and sanding back until pores are filled is needed to get a mirror finish. In fact, this is needed even with pore filler  . There's no set number of coats.Pore filling using standard materials/established methods generally does not disturb the glossiness of a finish. In fact some arguably make the gloss and grain pop more. Here's a link to photos and video of preston Thompson using eggs whites ala what Brad hall suggested, to pore fill koa: http://pktguitars.com/acoustic-guita...fret-0-guitar/ I personally use foam rollers and varnish for my finishes. The pore filler that was recommended by Bruce sexauer is zinsser seal coat that is basically a shellac and is 100% wax free. Any dewaxed shellac would also work to fill. Good luck! Sam Last edited by Sam VanLaningham; 11-16-2016 at 10:55 PM.
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#204
11-17-2016, 04:10 AM
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Quote:
Actually, the only examples of his work i've seen are with a satin finish lacquer. Its not the same as high gloss, but it looked pretty reasonable. Because its requested so rarely by his clients, he doesn't currently have any high gloss lacquer and has had to order that specially. Along with that, unless I do the job myself with spray cans, he's the only guy around i've found that can do it. From what you, (and Sam below) have said, i decided that a pore fill was/is definitely in order or at least super helpful, so after plenty of searching online I've actually just this morning found a place in the UK that sells Aqua Coat water based grain filler, same stuff that LMI sells, i've seen a few positive reviews on this, and seeing as the absolute earliest we could spray the guitar next week would be thursday anyway, i've shelled out the extra postage charge for the 'fast' shipping (unfortunately no estimated timeframe) and hopefully i'll get it and be able to get it on before thursday and because of this new development i'm not in a rush anyway. Quote:
as mentioned previously he hasn't ever sprayed guitars before, hes a furniture guy so although he has his method, i'm basically adapting it/modifying it to what I need. I just need to work out what that 'method' actually is/should be! As I just wrote above, from what you and Charles have said, it does sound like pore filler should be the way forward so after finally finding some "nearby" i've put the order in and hope it arrives as soon as it can. On a side note, I was considering/its been suggested to me that perhaps I could/should have gone the french polish route. This is something I also have 0% experience in, but perhaps its something I need to look into for future projects, at least as an option.
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#205
11-17-2016, 09:15 AM
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The Aqua Cote should work fine. It appears to be very similar to the product I described previously called Brite-Tone that is packaged for and sold by a Canadian company. I found it took numerous applications, but worked well.
Probably, it will be compatible with whatever lacquer your finisher plans to use. Ideally, you/he should do some test samples to ensure materials and process work and you get a result you like. Even with a pore filer, more than three sprayed coats will be required for a mirror-gloss result. I'd suggest researching typical processes and sequences used for making mirror-gloss finishes: there is more to it than the sequence you have suggested. French polish is an accessible finish, something you could do on your kitchen table. (I don't recommend spraying lacquer in your kitchen.  ) It is "low-tech" and requires simple materials, a bit of know-how and practice.
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#206
11-17-2016, 09:30 AM
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I recommend French polish. You built the guitar from scratch, why not finish it yourself?
I fill the grain by French polishing. Pumice works but you need to be careful to not use too much or it will be visible. I just apply more coats of shellac until pores are filled to my desired level. Sometimes I stop at about 95% filled to give it that antique look. I don't mind the extra coats required to fill the grain by rubbing since the process is enjoyable. Also, my time is free so I don't mind. You can finish the guitar with less than 30 grams of shellac flake and a liter of grain alcohol. You need cotton rags, some oil (I use olive oil), and 400 or 800 grit wet/dry paper. Sand every 3 or 4 coats to level. The process is relatively clean, low emission, impervious to dust contamination, and easy to touch up. You can polish and wax it to finish or just stop and accept the finish "off the pad". (You can drink the leftover alcohol.)
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#207
11-17-2016, 12:43 PM
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I don't know if thin CA is easily available, but it works quite nicely as a pore filler. Put a little puddle (test on scrap to determine how much) of CA in the center of the plate, then use a plastic card to spread in around, covering the entire surface. Get it as smooth and as thin as you can, it dries really hard and you will need to sand it smooth.
You also have to work very quickly, and keep the card moving, it cures in less than 5 minutes, maybe less than a minute, depending on the CA. Test it on scrap first, it's not a difficult technique to learn, but it's not likely to get it exactly right the first time, and it's unpleasant to have to sand it off and start over. Most importantly, although CA is technically non-toxic, it is an extreme irritant. This has to be done in a well ventilated area, preferably outside, with a small fan behind you blowing the fumes away.
__________________
Rodger Knox, PE 1917 Martin 0-28 1956 Gibson J-50 et al
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#208
11-17-2016, 02:44 PM
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Quote:
You just have to look at the last 10-15 posts and my total and utter complete lack of finishing knowledge to see why I had planned for someone else do the finishing, especially if i was aiming for the high gloss finish I decided to go for on this one. If that wasn't the plan, i would have gone for a simpler oiled finish which I would have been able to manage myself. Quote:
I did end up buying some Aqua Coat pore filler but i've just read another recent thread on here where the results with a french polish finish and the Aqua Coat apparently didnt turn out so great
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#209
11-17-2016, 03:46 PM
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I think using pore filler and french polish are mutually exclusive. As I understand it, the process of french polishing fills the pores and there is no need for separate pore filler.
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#210
11-17-2016, 03:53 PM
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Quote:
Charles, Earlier in the post he mentioned that the spray guy is planning to use a 2 Part Polyurethane. As I understand it, those can build pretty quickly in relatively few coats.
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