nitro finish what I learned

The Achilles' Heel of Luthiery
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tippie53
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Joined: Fri Mar 03, 2006 7:09 pm
Location: Hegins, Pa
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nitro finish what I learned

Post by tippie53 »

I am glad to see so many posting on their finishing process. I hope that I can help a little and share some things I learned
First off , there is so much more to do than just spray.
I have posted about prep a number of time so I won't repeat that sermon.
So once your done with prep the actual finish process starts.

MIX
In nitro I have used
Sherwin Williams
Mowhawk
Cardinal
Behlen
Minwax
I learned that the plastisizers in the finish are what make them different some are harder than others.

The thin mix is as important as the material. I don't think any are good out of the can so here is what can make things flow better.
Nozzle
this controls the material. Too large or too small will cause issues so find the one that best suits the material.

I have a fuji semi pro 2 1.0 and 1.3 nozzle

I find the 1.0 is best for my application. I also check the viscosity so pay attention to the details. The secret is getting the finish on efficiently so it can flow out self level and cure.

Too close when you spray can cause micro bubbles in the finish

I found for me the best mix is to use a bit more thinner on the first few coats. My thinner mix is usually 3 parts thinner 1 part retarder.
now in the cup for the first spray I will fill the cup about 1/3 and spray 2 coats with a mix of about 50/50. Then my mix after will go to 65 finish 35 spray using the thinner I have pre mixed. I can get a good smooth finish on about 4 coats. I spray about every hour. I do use my rotisserie to help control flow and level and eliminate sags and runs.

I have a spray booth and being able to control the air , temp and rh aids in curing. I can dry sand in 24 hr. I like to use 400 grit and will sand to get as level as I can. I don't get too aggressive just want to get reasonably level. Then with a good wipe down and clean up do another 3 coats. This I will be sure to level and get all the voids sanded level.

At this point I do my "body and fender" work. I will drop fill anything I miss and get all the hollows filled. Allow about 1 hr and spray a coat of about 50 50 let set over night and level sand to get ready to buff.
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
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