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| Spraying Varnish http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=38219 |
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| Author: | dmills [ Sat Nov 10, 2012 7:46 pm ] |
| Post subject: | Spraying Varnish |
Just finished #5 last month after a long gestation period and decided to try spraying varnish as the finish on this one. I had brushed on Behlen’s Rock Hard varnish on the last 2 and while the end result was very satisfactory, the process was time consuming and challenging dealing with brush marks, witness lines and the constant and ultimately futile effort at keeping the brush clean and “sand” free. Finally switched to cheap throw away foam brushes and a thinner varnish mix which solved the “sand” issue but the process still took a big chunk of time to complete. So I picked up a set of Woody Brackett’s (“Woody B” on the forum here) varnish spraying DVD’s and gave it a shot. Picked up one of the little Italian Walcom EGO HVLP guns Woody recommends and used the Sherwin Williams Wood Classics fast drying oil varnish that Woody also recommended. I ended up with some slight “orange peel” that, due to the fast approaching Chicago fall temperature drop, I could not precisely identify as to whether the culprit was a pressure issue or an application issue, but the condition was minimal and leveled easily. I pore filled the back and sides with Z-poxy and padded a few coats of shellac on the top to seal it prior to spraying the varnish. The Sherwin Williams varnish is a very pale blonde finish compared to the darker toned Behlen’s and sprayed easily using the mix ratio recommended by Woody. I did a final leveling with 400 grit paper and let sit for two weeks and then wet sanded up to 2000 grit and then buffed it out with Menzerna fine and very fine compounds. I quickly achieved a high gloss finish which I guess speaks to the hardness of the SW varnish product. And surprisingly, I did not see a single witness line even during the first aggressive leveling sand. I’m guessing spaying varnish cut my application time by at least 50% and the associated headaches by a significantly higher percentage. If you already have a decent compressor in your garage or workshop you should give it a shot. |
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| Author: | Don Williams [ Sat Nov 10, 2012 10:51 pm ] |
| Post subject: | Re: Spraying Varnish |
Looks nice. How long did you wait between final leveling and buffing? |
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| Author: | dmills [ Sun Nov 11, 2012 2:35 pm ] |
| Post subject: | Re: Spraying Varnish |
Hey Don, 2 weeks which seemed sufficient based on the nice high gloss. |
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| Author: | CharlieT [ Sun Nov 11, 2012 3:35 pm ] |
| Post subject: | Re: Spraying Varnish |
Doug - those photos look fantastic. Thanks for sharing them. I haven't used varnish yet but plan to. So you feel the SW varnish gave you a pretty hard finish? |
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| Author: | dmills [ Sun Nov 11, 2012 5:47 pm ] |
| Post subject: | Re: Spraying Varnish |
Hey Charlie - It polished up to a high gloss which I am assuming is indicative of a fairly hard finish. Any one on the forum seen any hardness data for the various varnish types in common use for guitar finishes - Behlen's, Sherwin Williams, Pratt & Lambert? |
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| Author: | steve malone [ Mon May 13, 2013 5:38 am ] |
| Post subject: | Re: Spraying Varnish |
I am too spraying with varnish and seems to take forever to dry. I have used mineral spirits and Naptha which makes it so I can sand after 24 hrs but I have noticed that on aggressive leveling it is still tacky underneath. I also used mineral spirits to wipe dust clean which I think redisolved the varnish. I am coming close to the final coat. What I am seeing is some sagging in places. I noticed that each time it gets a little less than the last. My question is how can I prevent the sagging. I have tried a 50/50 mix and I just tried a 20 % of Naptha alone. I am using Ace varnish and it doesn't give and advice on diluting for spraying, or maybe I just missed it because the writing on the can is so small. All in all I am happy with the gloss level that I am seeing with it, but in the future I plan n sing the SW product mentioned above or nitrocellulose. Also my polishing that I plan on using will using 600 wet/dry, 0000 steel wool, then 1400. This may seem like a crazy question but am I using the steel wool in the right sequence. I then plan on using automotive plishing compound, then a few coats of wax on top. Any advice is appreciated Steve |
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| Author: | mkellyvrod [ Mon May 13, 2013 5:49 am ] |
| Post subject: | Re: Spraying Varnish |
Doug, super nice binding job on that soundhole! |
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| Author: | Casey Cochran [ Mon May 13, 2013 7:45 am ] |
| Post subject: | Re: Spraying Varnish |
Beautiful guitar! Thanks for the information about the varnish. Where do you find those fine-line purflings? |
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| Author: | douglas ingram [ Mon May 13, 2013 8:12 am ] |
| Post subject: | Re: Spraying Varnish |
steve malone wrote: I am too spraying with varnish and seems to take forever to dry. I have used mineral spirits and Naptha which makes it so I can sand after 24 hrs but I have noticed that on aggressive leveling it is still tacky underneath. I also used mineral spirits to wipe dust clean which I think redisolved the varnish. I am coming close to the final coat. What I am seeing is some sagging in places. I noticed that each time it gets a little less than the last. My question is how can I prevent the sagging. I have tried a 50/50 mix and I just tried a 20 % of Naptha alone. I am using Ace varnish and it doesn't give and advice on diluting for spraying, or maybe I just missed it because the writing on the can is so small. All in all I am happy with the gloss level that I am seeing with it, but in the future I plan n sing the SW product mentioned above or nitrocellulose. Also my polishing that I plan on using will using 600 wet/dry, 0000 steel wool, then 1400. This may seem like a crazy question but am I using the steel wool in the right sequence. I then plan on using automotive plishing compound, then a few coats of wax on top. Any advice is appreciated Steve Sags are from a too heavy application, possibly holding the gun too close or not having the gun moving when you pull/release the trigger, or moving just too slowly. You may also be seeing early sags remaining from not thoroughly leveling. If you are getting new sags then they won't likely be in the same place. As you mention that they are getting smaller you may just be progressively sanding them as you prep for and apply each application. Check the applications of your spray room, too. It should be warm (not hot) and dry. Pre-warming your work to be varnished helps, too. The varnish has more initial "grab". A bit of Japan Dryer will help you varnish dry more thoroughly. Remember, varnish dries by evaporation. This means that the surface dries earlier than the inside. If you are building up coats it does not hurt to leave the base coats to dry longer ensuring a thoroughly dried finish. OK, so its tough to wait...just pace yourself. Its faster to wait than it is to correct the issues of rushing. |
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| Author: | steve malone [ Mon May 13, 2013 8:38 am ] |
| Post subject: | Re: Spraying Varnish |
Thanks Doug, I appreciate your help. I am new to spraying and I have been very careful on how I moved and tried, keyword try to put on too thick of coats. I have scraped and sanded down between coats, up until the last coat I was applying a hot coat over each coat, and I have stopped that because I was worried about to thick of an application. I looked at it this morning and it doesn't appear to have sags, just I can tell its not level. It is still tacky and I am tempted to throw a hot coat over it to try to level out, but I also think that if I wait and sand the next coat may be the keeper. I am going away for work and probably wont be able to do anything additional for 5-7 days. And the temps have been far from optimum here, so I know that has been an issue with drying times, although I really like the loo of varnish, and it doesn't smell bad either, In the future I probably will go with nitrocellulose. Does nitro have a less tendency to sag or is it about the same for every type of finish and its more of an application problem Thanks |
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| Author: | douglas ingram [ Mon May 13, 2013 9:09 am ] |
| Post subject: | Re: Spraying Varnish |
Steve, Every type of finish will have its vices. You choose your poison! I used to hot coat more than I do now, I've moved away from it. It works OK if your timing is just right and if you are trying to build the finish, but your inadequacies accumulate. Even though it takes less time, ts easier to do one coat at a time; each application dries better and you can level much more easily. The time for hot coating is just after the first coat is no longer tacky. Just after. If it is still tacky then its too early. You never really get good with any finish the first time through. Learn a material and master it. Like a good marriage, you don't really get any good at it by constantly trying new partners. Patience is a virtue, work with the process rather than fighting it. I like varnish. I use it a lot on my canoes and paddles. I go through liters and liters of the stuff. I don't usually spray it as it stays wet and airborne for a long time and I don't have a spray booth large enough for the canoes. |
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| Author: | Steve Kinnaird [ Mon May 13, 2013 9:21 am ] |
| Post subject: | Re: Spraying Varnish |
mkellyvrod wrote: Doug, super nice binding job on that soundhole! +1 to what Martin said. Indeed, can you tell us how you did that? Thanks, and congrats! Steve |
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| Author: | steve malone [ Mon May 13, 2013 10:07 am ] |
| Post subject: | Re: Spraying Varnish |
Thanks Doug, Yes I would imagine it would be tough to get a canoe in a spray booth. I just looked at it closely again and I see no sags and it is not as badly unleveled as I thought it was. A good sanding and another thin coat in a week I think it will be something I can live with for my first spraying job. I probably will have to wait a month for it to cure before buffing out. Any suggestions on how fine a grit sandpaper I should use. The finest that I could find locally was in an automotive store and that was 1400 grit. Also should I even bother with the steel wool and just start at 600 grit and work finer from there. I have done many finishes before and honestly I never buffed out. I was always happy with the final coat (furniture) but I do know for a nice finish I will have to buff out. Thanks |
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| Author: | MikeyV [ Mon May 13, 2013 11:14 am ] |
| Post subject: | Re: Spraying Varnish |
Someone mentioned above that Varnish dries by evaporation, which is exactly false. It cures via oxidation of the oil base, which is sped up by using a catalyt. Lacquer dries by evaporation of solvent, varnish cures through a chemical reaction. Just saying. But it is true that the surface cures faster, but only because it is exposed to more oxygen. |
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| Author: | douglas ingram [ Mon May 13, 2013 12:09 pm ] |
| Post subject: | Re: Spraying Varnish |
That would have been me and I accept the correction. The net impact on us as builders remains the same either way. |
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| Author: | Beth Mayer [ Mon May 13, 2013 6:11 pm ] |
| Post subject: | Re: Spraying Varnish |
Hi Doug. Beautiful instrument and nice finish. Is the varnish as nasty to work with as Nitro? Do you have to have explosion proof fans if using in a booth? I have to spray outside, andI have to cure my instruments in the shop, so I don't go in there for a couple weeks when they're hanging with nitro. Because of that, and how bad the fumes are (though I always wear a respirator and goggles) I was going to try waterborne in the future. But this varnish interests me if it's not as dangerous as Nitro to use. |
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| Author: | Tony_in_NYC [ Mon May 13, 2013 9:32 pm ] |
| Post subject: | Re: Spraying Varnish |
That's a beautiful finish. |
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| Author: | Barry Daniels [ Wed May 15, 2013 8:00 am ] |
| Post subject: | Re: Spraying Varnish |
Steve, to answer your question about steel wool. Avoid it if possible. It leaves lots of steel particles and it also does not leave a level finish surface. |
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| Author: | steve malone [ Thu May 16, 2013 6:08 am ] |
| Post subject: | Re: Spraying Varnish |
Thanks Barry, I kind of thought that since I am going that fine of grit that the steel wool would just be redundant. I have heard about the rust and steel wool so I was planning on sing it in the final finish buffing, but I think I should be able to get a nice finish going up to 1400 grit |
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