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| Removing runs, at what point? http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=11290 |
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| Author: | Chris Cordle [ Thu Mar 15, 2007 12:09 pm ] |
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Here I am seeking advise again. Please know that I am grateful for all the fine help, suggestions and ecouragement I recieve here. I am currently doing the finish on #2 with ColorTone brushing varnish, chosen mostly for it's safe use in my house and around my children. I must say I am quite pleased with it's flow-out and it is building up quite nice. I am currently on coat 5 with one more still to go tonight. Tomorrow the directions call for a level sand with 800 and possibly, depending on how successful I am at leveling without going through, two more final coats. My question is, at what point should I remove some small sags and runs and what grit would you suggest? |
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| Author: | Jim Watts [ Thu Mar 15, 2007 12:42 pm ] |
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I would scrape or sand the run after it's nice and hard, then sand the eitire instrument if your that close to being finished and proceed as scheduled. In general if I get a sag or run I try to take it out before the next coat. That might be just me however. |
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| Author: | Chris Cordle [ Thu Mar 15, 2007 1:15 pm ] |
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The directions from StewMac are this: Apply 2-3 coats daily, no longer than 3 hours apart. No sanding between coats if timeline is followed. Let set overnite. Day 2. Sand with 320. Directions do not specify whether the goal here is to level or just to scuff. Then repeat with 2-3 top coats. Let set overnite. Day 3. Attempt a level sand with 800 without going through. If level is reached successfully, follow up with 2 more coats. If unsuccessful, 2 more coats and another attempt at level. For me, the big question not answered in the directions is am I going for level between days and should I be removing any sags or runs at this time as well. |
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| Author: | gozierdt [ Thu Mar 15, 2007 2:12 pm ] |
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With nitro, where successive coats burn in well, I remove runs after letting the previous coats set at least 24 hours. If it's a big run, where the center may not have fully dried yet, I'll wait longer, depending on temperature. Sags usually are safe the next day. I like to use a freshly sharpened scraper to remove the material above the surface, then proceed with a normal sanding schedule. The scraped surface also shows if the center is hard or not. If I see any sign of "gooiness" , I stop and wait another day. |
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| Author: | Daniel M [ Fri Mar 16, 2007 9:25 am ] |
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Yeah... Get rid of any surface imperfections as soon as you can. Applying more finish over a sag or run can cause it to dry very slowly, making it very difficult to remove without marring the surface. Olfa knife blades are great for scraping finish. They are sharp & flexible & you can snap off sections just the right length for the job you're doing. |
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| Author: | Steve Saville [ Fri Mar 16, 2007 9:59 am ] |
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[QUOTE=uncleshish].......... For me, the big question not answered in the directions is am I going for level between days and should I be removing any sags or runs at this time as well.[/QUOTE] Chris, Remove the sags ASAP. after the finish is hard I would use a scraper or a razor blade on runs, if I ever had any.  
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| Author: | Chris Cordle [ Fri Mar 16, 2007 1:00 pm ] |
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I was able to remove all the imperfections by doing an initial sanding with 400 and then leveled with 1000. I scraped the couple runs using a razor blade very carefully. Looked pretty good, then the directions called for 2 more final coats. I am now letting it cure for the recommended time period before wet sanding with 1000. The problem I forsee is the final 2 coats left the unavoidable unevenness caused by using a brush and I can't see where wet sanding with 1000 is going to bring it back level again. I can sure see the advantages of spraying, I only wish it were an option for me at this time. |
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| Author: | gozierdt [ Fri Mar 16, 2007 1:20 pm ] |
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Chris, I think that you will need to pick the grit size you start with from experimenting a little with either the top underneath the fretboard, or a separate sample. Lacquer is very hard to brush (and get a smooth result), as you've found out. I suspect you'll need to start out with 220 or even 180, get the surface "almost" flat (only a few evenly distributed shiny spots that haven't been sanded yet), then start up through the grits 320-400-600-1000-etc. The saving grace of lacquer is that it burns into the previous coat well, so if you sand through one coat into another, you don't get a white line around the boundary. You will need to be very careful not to sand through to bare wood with the coarser grits- don't use them at all on the edges. If you do sand through, do a couple of extra coats over that area, then another coat or two over that surface of the guitar, remember where you burned through, , and sand lightly in that area the next time. Don't ask how I know... (at least this process worked for me) 
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| Author: | gozierdt [ Fri Mar 16, 2007 1:24 pm ] |
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I just noticed you're using varnish. I've done quite a bit of varnish work on mahogany boats. I think my comments will still work for you. The burn-in isn't quite as good as lacquer, but I don't think you'll have a problem. You'll want to avoid sanding through as much as possible anyway. |
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| Author: | Chris Cordle [ Fri Mar 16, 2007 2:04 pm ] |
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[QUOTE=gozierdt] I just noticed you're using varnish. I've done quite a bit of varnish work on mahogany boats. I think my comments will still work for you. The burn-in isn't quite as good as lacquer, but I don't think you'll have a problem. You'll want to avoid sanding through as much as possible anyway.[/QUOTE] Gene, Thanks for the tips. As far as the directions go, I've now applied the amount of coats called for before final wet sanding and buffing. Are you recommending that I start off a little more aggressive in grit on my "final sanding" and work my way up to the higher grit? I wasn't planning on applying more finish unless something happens causing me to do so. |
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