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 Post subject: Re: Finish issues
PostPosted: Thu Apr 11, 2019 3:41 pm 
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Brazilian Rosewood
Brazilian Rosewood
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Joined: Mon Dec 27, 2010 9:06 pm
Posts: 2504
Location: Magnolia DE
First name: Brian
Last Name: Howard
City: Magnolia
State: Delaware
Zip/Postal Code: 19962
Country: United States
Focus: Repair
Status: Professional
Borg wrote:
Mike_P:
B. Howard: No sunlight but circulating air could be an issue. I spray in the doorway and return the body to a hook well back inside. I don't have a way to measure coating weight. I simply hold the body at an angle that allows me to see that the coat is wet. I rarely if ever see any sags or runs which is my sign that the coat is not too heavy.
.


Temp, humidity, air circulation, it all matters. And newer nitro formulations have become quite finicky due to the change in solvents over the years. Your "Compliant" reducer isn't helping things either I suspect. Being compliant means typically slower, less volatile solvents. I suspect the one hour between coats to be the problem here mostly due to a very slow and heavy bodied reducer.

You should get a mil card and use it to determine what your wet coats actually measure. Then you can actually calculate exact final dry film thickness as well as know if you are applying to thick wet. Here is some info on that. https://howardguitars.blogspot.com/2015/06/spray-gun-setup-technique-by-brian.html

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 Post subject: Re: Finish issues
PostPosted: Fri Apr 12, 2019 10:31 am 
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Walnut
Walnut

Joined: Fri Apr 05, 2019 8:21 pm
Posts: 22
Country: US
Focus: Build
Status: Amateur
B.Howard
I sprayed some lacquer yesterday with no thinner and was able to achieve very good results. My problems in the past with this I think had to do with following the "rule of thumb" of 8 to 12 inches from the surface that most spraying tutorials call out. Your article validated what I discovered yesterday and that is to move closer. Technique then becomes even more critical which I think I can handle.
Your site has wealth of information.
Thanks for your help. I think I am on my way to producing some much better results.


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 Post subject: Re: Finish issues
PostPosted: Fri Apr 12, 2019 7:03 pm 
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Koa
Koa
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Joined: Tue Jan 22, 2008 8:57 pm
Posts: 586
Location: Austin, Texas
if you were able to spray effectively with no thinner, then you don't need any...in general reducer is used to achieve a viscosity a spray system is capable of shooting. for example with my system I have to use thinner because my compressor isn't capable of pushing a gun to shoot nicely without being thinned. as Brian mentioned in an earlier post be aware that the use of retarder will delay all aspects of shooting lacquer...

and another little thought: don't be tempted to put something out in the sun to speed up curing...most likely that will result in any solvents still flashing off creating bubbles in the film. the first thing I ever sprayed was an 11 lf curved bar for a local club (talk about a nightmare of a learning curve...sheesh)...on the day of delivery it was agreed that the bar's labor would unload it from the trailer I had borrowed...well, they were behind schedule and hadn't even complete the tear out of the old one when I arrived...long story short my project ended up sitting out in the sun while those *edited* decided to take a brunch break...heh...it finally got brought in just as the finish barely started to have bubbles created in it (yeah, as noted first spraying project and even though 2.5 weeks had passed since the final coat it was still arguably too fresh to deliver)


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 Post subject: Re: Finish issues
PostPosted: Tue Apr 16, 2019 10:50 am 
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Walnut
Walnut

Joined: Fri Apr 05, 2019 8:21 pm
Posts: 22
Country: US
Focus: Build
Status: Amateur
I learned years ago that the sun has negative effects on just about anything but plants. I was modifying some kitchen cabinet doors years ago. I was adding a shaker look to otherwise flat doors. Easy enough except as I glued the perimeter boards I laid them in the sun to hurry drying. They warped and warped while the glue was still drying. Warped beyond repair. Fortunately they were easy to make from scratch but needless to say it was not a profitable job.

I started building guitars about a year ago and the learning curve has forced me to learn to be patient. A very difficult conversion for me. Being a "results NOW" person is not conducive to this kind of craftsmanship.


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 Post subject: Re: Finish issues
PostPosted: Fri May 03, 2019 6:58 pm 
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Walnut
Walnut

Joined: Fri Apr 05, 2019 8:21 pm
Posts: 22
Country: US
Focus: Build
Status: Amateur
Update.
Buffed out another body that I sprayed with no thinner. Solvent pop was reduced by about 85% which is encouraging. Then I checked my wet film thickness and discovered that it was over 6 mils. The material I use recommends no more that 4. Modified my technique and will see how it goes.


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