Venom300 Posted February 17, 2006 Report Share Posted February 17, 2006 Hey I am new to this whole guitar thing and i keep working on this guitar but everytime i sand it this happens on one spot or another. is this because i sprayed it wrong or is it fixable... somene please let me know. I wanna be done with this guitar as soon as possible. Steve Quote Link to comment Share on other sites More sharing options...
RAI6 Posted February 17, 2006 Report Share Posted February 17, 2006 A sharper, and a little closer, picture might help.... Quote Link to comment Share on other sites More sharing options...
skatz Posted February 17, 2006 Report Share Posted February 17, 2006 it sorta looks like b4 you started to paint you didnt sand it well enough and the paint is uneven. Quote Link to comment Share on other sites More sharing options...
mikhailgtrski Posted February 17, 2006 Report Share Posted February 17, 2006 Hard to tell for sure, but it looks like you had some sags in your finish. Are you spraying polyurethane? It doesn't burn into the previous coat, so you'll see the layers if you sand through the top one. But yes, a better pic would help. Quote Link to comment Share on other sites More sharing options...
Venom300 Posted February 17, 2006 Author Report Share Posted February 17, 2006 Hard to tell for sure, but it looks like you had some sags in your finish. Are you spraying polyurethane? It doesn't burn into the previous coat, so you'll see the layers if you sand through the top one. But yes, a better pic would help. Yeah the pic is bad i will admit but was the best i could do and still get the imperfection to show up. Yes i am spraying urethane. That is rather helpful. How do I fix This Particular problem easily? On like a scale of one to ten of being a problemm, what would you, as a better builder place this at?.. this way i know how much of a pain in the ass it is gonna be. I appreciate the feed back Steve Quote Link to comment Share on other sites More sharing options...
Southpa Posted February 17, 2006 Report Share Posted February 17, 2006 (edited) What I see are separate layers of poly showing thru your sanding as mik mentioned. Each layer constitutes 1 shooting session. Its difficult to tell which way it is going just by looking at snapshots. If the areas are getting larger as you sand then you may as well strip it down and start over. If they are getting smaller then you might be able to salvage most of your progress by taking them out entirely. There could be a number of reasons why this occurred. 1. The guitar wasn't sanded flat to begin with. Any low / high areas remain throughout the finishing process. 2. The finish was sanded unevenly and/or too vigorously. Its clear that you broke the barrier between layers. 3. The finish was applied unevenly. All or any combination of the above could be the reason. You have to prevent it from happening again. Check the flat surfaces with a straight edge. If you find dips and high areas that coincide with the little "islands" then surface sand the entire face until flat. The poly finish has to be thoroughly scuffed with 320 or finer grit paper between shooting sessions. Use finer grit on edges and go lightly. You have to balance your sanding with the amount of finish you are applying. Too thin a finish and too much sanding = breakthrus! Thick is OK so long as its laid down on a flat level surface. When I spray poly the first few sessions are done on a hanging guitar. The rest is done with the guitar laying flat and level. The poly spreads out nicely and levels itself. However, I'm still careful around curves, body carves etc. Everything must be done with "evenness" in mind. If you start with an even surface then everything else is easy so long as you stick to the rules. When spraying make sure your spray pattern overlaps evenly. When sanding make sure its done with even pressure and sanding patterns overlap evenly. Constantly monitor your progress and the condition of your sandpaper. And above all know when to stop! Edited February 17, 2006 by Southpa Quote Link to comment Share on other sites More sharing options...
Venom300 Posted February 18, 2006 Author Report Share Posted February 18, 2006 alright now thats more helpful. I sprayed the first couple of coats with the guitar hanging up but then moved to having the guitar level. Is there any way to figure out how to get it level or is it just a practice make perfect type thing. and yes its just getting bigger each time i sand. So guess i'll just respray the back since thats the area where i am having my problem. I appreciate the help you guys let me know if you have any other usefull tips for spraying poly or can tell me where i can get a cheap laquer kit. Steve Quote Link to comment Share on other sites More sharing options...
Setch Posted February 18, 2006 Report Share Posted February 18, 2006 Those are witness lines, where you cut through one coat of finish into the coat below. The way to fix them is to lay your coat down smoothly and thickly enough that you don't sand through when levelling. Some witness lines will buff out, but not all, so you're best to avoid them if possible. Nice even coats, and extra care on the last few should stop this happening. Quote Link to comment Share on other sites More sharing options...
Southpa Posted February 18, 2006 Report Share Posted February 18, 2006 (edited) Is there any way to figure out how to get it level or is it just a practice make perfect type thing. You mean the finish? or the guitar itself while spraying? When levelling the guitar you can use a bubble level, I prefer an angle finder and make sure its level in every direction. Its nice if the table you lay it on is level to begin with. Otherwise I use an assortment of shims, blocks, whatever to get things right. Once the guitar is perfectly level gravity takes over when spraying. Avoid too much buildup around edges or you WILL get a series of sags, curtains etc. running down the sides. But the center flat portions will settle out nicely to a smooth mirror finish, to such an extent that you very likely won't have to do any wetsanding...job FINISHED! I do all my shooting outside so there is some risk of windborne dust, debris, insects landing on the surface. I try to avoid windy days. This method takes a bit more time because you can only work on one side of the guitar at a time. That means waiting until the first side has cured hard enough that whatever you lay it on won't make any marks. Edited February 18, 2006 by Southpa Quote Link to comment Share on other sites More sharing options...
Venom300 Posted February 20, 2006 Author Report Share Posted February 20, 2006 (edited) Is there a certain place you take the guitars so that they don't get any debris on them. I almost got a glass finish on this one the last time but there was specks of dust so i just figured i would sand. If you have any tips on how keep debris away I would love it.... it would make a lot of my work a lot easier. Steve Edited February 20, 2006 by Venom300 Quote Link to comment Share on other sites More sharing options...
Southpa Posted February 20, 2006 Report Share Posted February 20, 2006 Easy, just stick a cardboard box over it right after shooting. Or make a little tent out of plastic, like a tiny greenhouse. Quote Link to comment Share on other sites More sharing options...
Venom300 Posted February 20, 2006 Author Report Share Posted February 20, 2006 Easy, just stick a cardboard box over it right after shooting. Or make a little tent out of plastic, like a tiny greenhouse. Sweet I appreciate the news.. I'll try that and tell you how it works. I was alway mad because i like the shine without sanding but stuff always got in it. I didn't really think keeping it in a box would help but i guess i was wrong. Huh guess that why they don't pay me to think. steve Quote Link to comment Share on other sites More sharing options...
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