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| Five little helps, spraying glass http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10102&t=14658 |
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| Author: | Bruce Dickey [ Sat Nov 24, 2007 6:06 am ] |
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Nitro, laying down like a mirror, is a wonderful thing. It doesn't always. It likes to crawl, or fisheye. Anyway, hopefully someone will learn something, and leave a comment if you like. 1. Warm shop 70 degrees, plus warm Nitro, waterbath to 140 degrees, F, of course..... 2. Fill the soundhole with a flat object, like a butter dish lid. I've found when using a cupped dish, that it disrupts airflow. I'm thinking a balloon would also disrupt flow a little. Flat is good, air flows evenly. 3. Thin McFadden's Lacquer #L-3721 with Retarder/Thinner. (I use Sherwin Williams R/T #K27) Makes it flow and helps it dry a bit slower so it can flow on the surface. Without it I was spraying crystals. 4. 0000 Steel Wool to sand lacquer. Unbelievable help to getting the lacquer to lay out flat. When you do have those problem areas hitting it with steel wool gets it all sanded, seems to remove the lacquer where needed. I've wet-sanded and wet-sanded only to have glossy pits remain. The steel wool get's it done. Remember to bang the steel wool periodically to unload it of dried lacquer. I just sprayed two bodies after using this technique and wow, it's laying down so smooth. 5. Blowing off the instruments before spraying works great. But, since it's somewhat static clingy, tiny particles find their way back to the surfaces. Tack Cloth from the hardware paint department eats the last little bits of dust particles. Ask in any paint dept for the goo impregnated cloth, it works. |
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| Author: | A Peebels [ Sat Nov 24, 2007 10:14 am ] |
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Thanks Bruce. Good advice, Al |
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| Author: | joe white(old) [ Sat Nov 24, 2007 1:25 pm ] |
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Bruce, Since you invited comments, I'll add mine. While the steel wool is working for you consider this. The steel wool probably isn't "leveling" the lacquer as you would like. You mentioned glossy pits when using wet sand paper. The steel wool may actually be just reaching down into the pits and "scuffing" them instead of leveling out the small pit or fisheye. A fresh piece of 1000 grit wet/dry paper with some sort of flat backer will eventually get you leveled out just fine. When you see those little shiny pits,you know that you need to focus on that area a little more with the paper to get it nice and flat. On the tack cloth issue, there are tack cloths available called "non residual". These are formulated to be a little less tacky and are also less prone to leave some of the sticky residue behind which could easily ruin a nice clear job. |
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| Author: | KenH [ Sat Nov 24, 2007 2:46 pm ] |
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My first few Nitro sprayings were ok, but not what I had wanted. It wasnt until I started letting the third coat sit for a couple of days, then wet sanding with 1200 grit wet/dry paper that I was able to achieve the gloss that I wanted. I also do this to the 6th and final coats. After the final coat I let it sit for another few days before buffing. I'm still using Behlen's stringed instrument lacquer, which requires no thinning. It comes ready to spray from the factory. |
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| Author: | Bruce Dickey [ Sat Nov 24, 2007 3:20 pm ] |
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Thanks Joe, I just seem to never be able to sand enough to get all the pits out, especially with rosewood. I know part of my problem is prep with either an epoxy coating / fill or get the vinyl sealer that McFadden's recommends. Having no fisheye or crawling would help immensely. I have the spraying part down pat, it's what happens after the lacquer is on that is problematic. So sealing better would be part of that equation. Who knows I may just try shellac again as a sealer? The 0000 was just the ticket on the back of that rosewood SJ though, it's perfect now. Nothing like the whole back after ten coats of lacquer, just a little one inch by six inch area near the neck. It nailed that. |
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| Author: | vachterm [ Sat Nov 24, 2007 6:47 pm ] |
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So Bruce and the rest of you, how many shots of Nitro do you end up doing per guitar? just interested... Udi. |
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| Author: | KenH [ Sun Nov 25, 2007 12:56 am ] |
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with me it is 6 or 7 |
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| Author: | Bruce Dickey [ Sun Nov 25, 2007 9:45 am ] |
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Udi, I'm doing 12 to 13 coats. It's possible that these others spraying 5 or six coats are using a larger spray nozzle. It's important which nozzle is one the gun when you purchase it. I'm using a 1.8MM tip. Some of the automotive guns run 2.2 or 2.3 MM tips. I gave up on the Porter Cable Gravity gun with just a 1.5 MM tip. I have been toying with the idea of upsizing tips and spraying more lacquer per coat. Wow, it's pretty shocking to read that in five coats it's done..... |
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| Author: | Bruce Dickey [ Sun Nov 25, 2007 10:09 am ] |
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My glue pot doing double duty. 140 degree F lacquer sprays nicely. 
69 Tele Thinline Klone, someone gave me this body. I thought honoring the gift by completing the guitar would be good. I stained this will oil based stain. What a mistake. Fisheye/Crawling lacquer city. But I have it by the tail now. 
My son just graduated college, this is an OSJ for him. Check out the gloss before buffout. Only two more days. Can I make it before Christmas? |
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| Author: | vachterm [ Sun Nov 25, 2007 10:31 am ] |
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yeah,Bruce, thats exactly the reason i asked... i started out doing a thousand coats coz it seemed like thats what people where doing. than i kindda got the feeling that i could easily do with 5 or so. so it sparked my interest... |
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| Author: | MikeP [ Sun Nov 25, 2007 12:05 pm ] |
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The negative side of retarder is that it can greatly increase the curing time of the lacquer. I only use it when its too cold or too hot for proper spraying. When using oil based stains you need to wait at least 5 days for it to fully cure, maybe longer if the conditions are preventing a proper curing cycle. I've found that using the highest quality thinner helps a lot. |
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| Author: | Steve Kinnaird [ Sun Nov 25, 2007 2:48 pm ] |
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Bruce, that guitar is looking great. I want to agree with the gents above, and sound a caution about mixing that retarder in there. I was forced to borrow some lacquer from a friend, on an emergency basis. He had premixed his formula with some retarder purchased at an automotive supply. (This tidbit of info came out later.) Fisheyes all over the place. I called him and asked what was up, and he told me his mix formula. Said he had been using it for years. When asked if he had trouble with fisheyes, he said he usually did, and just thought it was part of the territory. When the gun was cleaned out really well, and some straight McFadden's shot through, all went smoothly again. Compatibility IS an issue. Advice would be a good thinner, used fairly sparingly, and the butyl cellosolve when necessary. (But even more sparingly.) Keep us posted, Steve |
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| Author: | Bruce Dickey [ Sun Nov 25, 2007 3:38 pm ] |
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Okay Steve, one question, what size tip you using? I think I could spray straight McFadden's too but I'll have to change out guns. It is possible to shoot yourself in the foot while reloading your pistol. Maybe I'm doing that? On the Tele above, it was definitely the oil-based stain I used from Lowe's Home Improvement that caused the fisheye crawl. The SJ above didn't have the same problem though, so I may have dodged that bullet with the high dollar Sherwin Williams product. It was $27 a gallon. |
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| Author: | Dominic [ Sun Nov 25, 2007 6:36 pm ] |
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I've always used a clean dry hand to do the final wipe of a surface before finishing. I was advised to do this by the manufacturers of a spray finish for surfboards I was using and the reasoning was that your hand can feel the surface better and does not leave anything behind as long as it is dry. Works for me. Dom |
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