thirdstone

Sorry about the photo I took it with my phone , it looked ok on the small screen. Hopefully i won't see them again but if I do I will take a photo then burn the wood. What happens is that I spray a wet coat and as it drys these bubbles appear . When sanded flat the void that is under the bubble goes all the way down to the wood base so you can't sand them out . when sanded they resemble white rings.It only happens on the front of the wood not the back, same piece of wood At the moment I have sprayed about 6 coats of wood sealer and i am wondering if I should chance another attempt with the lacquor or buy some rustins clear coat.

The latest drama , I was still having problems so I rang up the producer of the lacquor and was told that to keep the lacquor open for longer, to allow the thinners to get out I should increase the lacquor content. This I did the a reatio of one part thinners two parts lacquor. This reduced the amount of bubbles but still not good enough.Next was to use acetone as the thinners and spray from a further distance than normal with low pressure. The idea put to me was that this would make the majority of the thinners evaporate before it reached the wood. It works but the result is realy bad. I think even the lacquor was going off in the air as well resulting in very dry finish. In despiration I rang a renown guitar builder in Aus I know, I know I should have done this earlier but........... Guess what ; some pieces of mahogany react badly with nitro and thinners and you just have to go very slowly and be very careful with the sealing. Its so unique that the back of my piece of wood is not affected just the front. Back to square one ( for the 8th time)

Rustins wood bleach will bleach the wood but not the stain. You will have to sand it out. You could try rubbing thinners into it but I don't think it will get it completely out.

After spending a small fortune on prep wash , different brand lacquor and matching thinners, and a new spray gun i did'nt get anywhere. Next I played around with spray gun settings and I foud I could reduce the problem by droping the pressure to 18 psi and spraying very dry ,but not a very nice finish. I guess that this allowed the solvent to escape before the lacquor set. This is the crux of the problem I think, being that the solvent is still trying to evaporate but the lacquor is curing blocking the release hence the bumps. I increased the thinners ratio from 50/50 to 1 part lacquor to 1 . 5 parts thinners and it is spraying better but a bit too early to be confident that I have resolved the problem as I am still spraying a bit dry.Next is to spray a wet coat and see what happens. The weird thing is that I have used the same lacquor/ thinners set up before with no problem. Chunkylad what mix ratios do you use for your lacquor?

Still having problems, bought a new gun but no improvement. This is a pic of the problem.

I think I may have the answer. I will add this for referance for other people. from http://www.woodweb.com/knowledge_base/Bubb...er_topcoat.html woodweb.com Bubbles in lacquer topcoat What causes bubbles in lacquer topcoats? September 26, 2000 Q. I run a medium-size refinishing shop and from time to time we get small bubbles in our final coats. We use regular sanding sealer with two or more coats of various nitrocellulose lacquer. Retarder, different dry times, stripped pieces or virgin woods don't seem to have a connection. -------------------------------------------------------------------------------- Bubbles in the final topcoat can be caused by many things. Wood species also plays a part in this problem. More porous woods, such as oak, mahogany, and walnut, for example, will tend to bubble more than less porous woods or woods with tighter grain patterns. Most causes for bubbles can be directly related to stain not being properly dried prior to applying sealer and topcoat. What happens is that the stain is still releasing solvent after the sealer and topcoat have been applied, thus causing bubbles. The solution, of course, is assuring the stain has had sufficient time to dry before topcoating. Another cause is using a sealer and/or topcoat that is too high in viscosity. A lacquer or sealer works much better at 17-18 seconds viscosity in a No. 2 Vahn viscosity cup. Add a good grade of lacquer thinner and retarder in the right proportions to achieve the proper viscosity. You want just enough retarder to keep the lacquer open long enough to flow and rewet overspray when spraying a piece, but trying to achieve this with lacquer retader alone will not fix the problem, and will sometimes make it worse. Your ratios for thinner and retarder will vary depending on weather factors including humidity and temperature. This will be a trial-and-error process on your part to make it work. I will add that a nitrocellulose lacquer and sealer finish is more forgiving than a conversion varnish or similar finish. Bear in mind also that your stripped pieces may still retain some of the wash solvents down in the pores of the wood if you are not letting them dry long enough. There are many things to consider with this problem. Look closely at what I mentioned above and see if any of these causes may at the root of your problems. -------------------------------------------------------------------------------- From the original questioner: Thanks for the quick responses and advice. I have tried all the solutions in the past but without any consistent results. I know that as temperature and humidity go up it seems to happen more frequently. You're right that retarder alone increases the problem. I have had to re-strip many a piece before giving up on that as a solution. If any of you have any more advice, I would like to hear it. If it makes any difference, sometimes I can get satisfactory results from spraying the tops on their sides (only happens on horizontal surfaces) letting them de-gas easier. I'll try some retarder in with my regular thinner on the next tops and see if I can get the right combo. -------------------------------------------------------------------------------- Make sure that you are using a reducer that is of the same brand as your finish. You didn't say if you were stripping or not; if so, make sure all of the methylene chloride is out of the wood. -------------------------------------------------------------------------------- I often find that thinners and reducers can cause the problem you have described. A "hot" or fast-drying thinner with the incorrect air flow (fast or excessive) can cause the thinner to flash off too fast, leaving solvents under the dried film with nowhere to go, thus causing bubbles or pinholes. Viscocity means everything in situations with minimal air flow. Not knowing what products you're using other than nitrocellulose, I would suggest that you keep your lacquer warm and off the concrete to lower the viscosity, and if any reducer or thinner is needed, I suggest you use it sparingly. Also, while spraying, make sure you apply a wet coat, and check the air coming out of your gun. Too much can cause air to get trapped under your finish. -------------------------------------------------------------------------------- May I ask if you are using a lacquer that has lot of acetone in it? I did new and refinsh work for over 20 years and know what you are talking about. What are you using for a retarder? Also, what is your brand of finish (if you want to tell us), or are you in a state that requires low VOC's and you have one of "those" lacquer formulas that are a little temperamental? Bob Niemeyer, forum moderator -------------------------------------------------------------------------------- Since you said you have the problem on just the tops and not the sides, what I am about to recommend should help a lot. When spraying the top of a piece, many people have a tendency to apply too much material. Lighten up on the top some, don't cross-coat it or overload it with material. Just spray a medium wet to wet coat and that's it. Allow all coats to flash off or dry in between and also take the advice mentioned previously about reducing your material. Hope this is of some help. -------------------------------------------------------------------------------- You say that you see it more when it is humid; are you sure that it is not fiber stand you are seeing? There is bubble relaxer out on the market. Contact your supplier or look for more suppliers on the 'Net. I have used acetone to get rid of the bubbles and that seems to work. Finally, check the air pressure of your gun; too much will often cause bubbles.

Is it possible that bubbles in the lacquor in the gun pot go through the gun in the spray??

okay the progress so far , and its not good. After grain filling and sand sealing flat still getting bubbles forming in the lacquor as it drys I thought it might have been a reaction to the chemicals used in the bleach that was used to bleach the mahogany so I neutralised it the 3 different ways that rustins recommends. That didn't help. Next I went and bought a different acrylic lacquor and prewash but again that didn't help. Next I suspected that the Compressor was blowing out oil (water trap was clean) so I sprayed air on to a sheet of white paper , clean as a whistle. I am running out of ideas with no progress in sight.

Your dead right. I have to be honest and admit that after thinking about this quite a bit I realised that after grain filling I should have sand sealed to completely fill the grain. After the initial post I drop filled and resprayed , what a complete disaster , hundreds of airbubbles appeared as it was drying. I think that after wet sanding the lacquor I must have been a bit slack in drying the body befor respraying. I have now completely sanded off the finish and am in the process of filling and sealing the grain. Before I spray againg its gonna be flat as glass.And dry as .........., well you know!!

Grain filled Mahogany

Thanks for the thought , I do have a water trap but I must admit i have not checked it out for a while. The rustins plastic coating is getting tempting. I thought of using it this time but as you know I went for the nitro. I`ll give it one more go then it will be the rustins if I fail again..Kev

Well its all gone to hell again, Looks like I have some MAJOR moisture problems with my spray rig. I have been having problems with airbubbles coming out of the clear causing pinhole marks. I was getting close to resolving these by drop filling and sanding back, I did another coat of clear and the thing went mad with airbubbles. I tried sanding back but no use as the bobbles go right down to the base. UnFu****g beleivable. Back to striping the burst off.Again , This is getting a joke!! The proof

Okay guys , I have sprayed clear nitro over a sunburst and the clear has got some pin hole problems. I know the cause , being that I let it dry under a heat lamp ( so i'm learning as I go) I have sanded back with 400 wet and dry and most of the holes are gone but there is still quite a few left showing.I sprayed another coat , this time with body layed flat ,result is a small improvement. Now my question is , other than drop filling every hole to fix it, is it possible to spray a clear filler / sealer like sanding sealer or schallac to fill the pin holes? kev

Since that last photo I sprayed one more coat of yellow which gave it a very slight increase in yellow brightness. I did want the yellow to be brighter but i am in the ball park of what vintage Gibbo jrs are now after years of fading in terms of yellow tones. There is still clear to spray over which will bring it to life a bit more.Chunkielad the burst is trying to replicate the finish on the 55-57 LP Jr and thats what they look like. The major veriation they have is in the thickness of the outer black/brown (actualy very dark brown). I prefer the thinner version so thats what I did. The original guitars were hand sprayed in what I would imagine was quick time going on the unevenness of some guitars...Kev

yeah me too the woodwork looks very nice, good to see someone using something othr than flame or quilted maple. Dunno about green or blue(please not blue) though. Second thoughts green would work,Green on top and clear on the back and sides and oiled neck would be my pick.Green and gold very Aussi. Kev (Syd)

Back to where I was a couple of days ago. Back to wood top cleaned up This time I was able to spray the outr black first whic in hindsite is the way to go black outer Then I sprayed the transition brown (with a touch of red) At first I used the template method but after a couple of passes I thought I would spray freehand . This worked out well , I set the gun to low lacquor output and droped the press to about 20psi ,I did this so I could control the flow better. Then it was just a matter of spraying the yellow all over. Not yet finished but going ok. A bit darker than I wanted .

Well it was good, back to bare wood again after some bizarre flakes of dryed paint came off the template and embeded themselves down to the base coat.

Yep its still going. The burst has been giving me hell though. last count was 3 times back to wood after not getting the right tone of yellow. I have tried to do this with out resorting to lacquor by using wood stains and sealers but I have been unable to get the yellow bright enough. This is dispite bleaching the mahogany. This is pic of the burst with just the black; Body bleached and black stainWhen th yellow was applied it was a bit too dark ,I almost left it as it looked a bit like those 70 sg's that had a burst on them, any Wolfmother fans will know what I mean as stockdale uses one. The next thing I tried was also to put a coat of white lime on the top .Its oil based and so I sealed it in with schallac , I think it would have produced a good yellow but ultimately I lost my nerve as I thought of the long term consequenses. i did find a sealer that would carry the stain and maybe I will try it again on some other project. white lime So I managed to track down a supplier of Nitro and compatible stains in Australia ; Durobond and now I have resorted to a nitro finish. To start with I bleached the body "again" and grain filled with a yellow grain filler then i sprayed the yellow on the front and brown on the back , then clear over. This allows me to rub any bad overspray off if it hapened. Unlikely as when I did the parimeter black I had a teardrop template covering the body. It was about 10mm above the body.I know the usual practice is to do the yellow last but that is the colour I was having prblems with and I wanted to get that sorted first. The two dark lines between the neck and pup will rub off, Just an unusual overspray. I still have the transition brown to do but at the moment I am happy with the result so far dispite having to use lacquor.

Yeah I know but the inlay was staring at me from my computer and it was too easy to hit the buy button. and it was Easier than silkscreaning. I don`t think it detracts too much,it was never going to be an exact replica. Having lots of problems with getting the yellow bit of the burst bright enougth. One burst already sanded back and on to the next one. The non availability of the correct stains in Australia is stressing me out. You guys in the USA have it too easy . Any other Aussi people out there chime in with where I can get some dyes that can be disolved into lacquor (nitro) I have discovered that Feast Watson stains can be disolved into their sealer so I will give that a go.

Thats the one HG,any pics of it finished?? I contemplated extending the neck tenon through to the pup as well but decided against it as it (I thought ) would have caused finishing problems getting the neck to match the body. is that a maple fretboard on top of a mahogany neck?? Kev

HG I had the same problem tracking down LP Jr single cut plans but I came to the conclusion asyou. ie same outline as LP but with 1/4 inch added to the treble side neck cutout . This is to enable the full width tenon. Its interesting to note that PRS single cut does away with this feature. To my way of thinking they did this to enable mass production. That part is a bit vulnarable with out the neck fitted. They may also think that it aids neck access but I expect it would be a weaker neck join. There is a LP Jr doublecut plan on the internet which I suspect might be useful , I havn`t checked but it might be simply a matter of filling in the upper bout. Another observation is that the controls are the same position to the upper two of a LP. So to summerise I think that when Gibson designed the Jr they just took a LP 55 blank ,left off the maple cap and only drilled the two upper control holes, then they fitted the full width tenon as its less complicated than the LP join and didn`t require the big angle. The P90 got fitted as the humbucker was not yet designed. Why they fitted a dogear and not a soapbar I don't know but I am glad they did. Kev

Not tru(sic) , tru oil over water based stain works better as the tru oil won,t pull the stain out. Best result to yellow up the neck if you are going to spray lacquor is to add the stain to the clear lacquor.

Buy a pre slotted fretboard for a start, costs a little more but saves tool costs and it will be more accurate. If you buy fret wire in a coil you don,t need to bend it thus saving again on tooling. IMHO the minimum is a small soft head hamer , 6" hand smooth file and sidecutters and a radius sanding block to get the fretboard even radius. Thats the minimum. I would add to make life easy , a fret press is the best way to get em in, a proper fret file ,the fret saw to fine tune the fret slot depth after radiusing, diamond sharpening stone for leveling and if you re binding the neck the stew mac tang nippers are the ducks guts. alot of practice will go along way to getting a first up good fret job. Good luck

No not yet dressed just pressed in. I'll waint untill the neck is glued in before I dress them. By the way they aren't flat its just the way the photo looks.

-- why not personalize the headstock --put your own inlay on there in addition to the logo. Something. Otherwise, well, it's a shame, that's all. Cool binding though. I have made a JR MOP inlay out of gold and abolone MOP shell but the consensus here was No. I might make up a decal later. Once all the hardware is on I don't think it will matter that much. The LP Jr guitar is a pretty basic guitar and to load it up with show bits is not in the spirit.