spray booth and finish what I have learned this year

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tippie53
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Joined: Fri Mar 03, 2006 7:09 pm
Location: Hegins, Pa
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spray booth and finish what I have learned this year

Post by tippie53 »

It has been a while since I posted about my spray booth and what I learned about spraying. Well I learned a lot and will pass on what I have learned.
to start with I learned that the gun and how you adjust it is paramount to a good finish. In this case I am spraying nitro and using Mohawn lacquer with their vinyl sealer.
My filler is pretty much all aqua coat and I use the Jeff jewitt stains and color this you can get at LMI and Stew Mac. I don't sand much past 220 grit. I use mostly Industrial abrasives paper from Reading and Micro mesh. I also use a heat lamp to warm up the bodies and the spray guns. I have about 4 guns on the rack , and they are loaded with Clear , toner Sealer and touch up gun with toner for spraying necks.
Once the body is ready I use a deli cup and foam rubber to seal the sound hole . I mask off the fret board area and here is one trick the helps with figuring finish depth. I apply 4 pieces of tape to the masked off area and I can pull on off and measure the application of the finish. While not 100% perfect it is a good guide to what you have applied. I start with 2 coats of vinyl . That has 1 oz of retarder per 1/2 gallon and thinner applied to get the proper viscosity generally about 2 to 4 oz thinner per gallon. I adjust my sprayer to get something about the size of a fist out of the gun. The first coat is applied and you want to be sure you are not getting dusting where the finish is dry before it hits the body. After 2 coats allowing about 30 min between coats I lightly sand with 320 wipe with naphtha for dust and then apply filler, I may or may not color the filler depending on what I am doing with the body. I find the first fill works well with hand apply and then allow 40 min to set light sand with 320 apply 2nd and 3rd coat using a edge of a credit card as a scraper. Let set and then sand with 400 grit dry. Apply 2 coats of sealer and let set 90 min, This I will level sand with 600 grit wet sand. Now I can look close. I pull my first tape and measure. I am looking for about a .002 to .004 build. After level sanding I leave about half on the body. Now I can use toner if I wish or clear. I allow my heat lamp to warm the body to about body temp and heat my lacquer. I added another fan to my down draft table for better fume control.
On my spray table I added a window fan pulling fumes down into the down draft table. The guitar holder covers the motor and with the amount of air pulling this greatly reduces fumes. I also use furnace filters to grab over spray. The heat lamp helps with flow out and reduces orange peeling. I then set my finish up . Mohawk claims you can spray right out of the can. I have tried this and I think that you indeed can. The heat helps. I have a heater in my booth and warm the room to 80 to 85 degrees before spraying. I have my guns adjusted for that fist sized spray area. The one thing with the HVLP guns is how close you want to be to your surface. I find about 5 to 6 inches is about right for my spray condition. The one point that we have to consider is cure time. I still allow 2 weeks to cure. I will sometimes level sand the next day before the final coats applied. I also pull a tape after every spray session and this may be 3 to 4 coats. At the end I would like to see about .08 to .010 total finish applied. After buff and polish I can see the final thickness when I clear the bridge area.
My buffing wheel is the arbor type and I use Menzerna cakes Medium , finish and 175 the wheels I get from Jescar , Grizzly and crestwell plating. I like Domet and flannel . My wet sanding is this I use a festool sander about medium speed , start with 600 wet to about 3/4 of the orange peel then 800 to level. Then 1200 , then 1500 , then 2000 3000 and then micro mesh. Buffing takes me about 1 1/2 hours.
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John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
tippie53
Posts: 7011
Joined: Fri Mar 03, 2006 7:09 pm
Location: Hegins, Pa
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Re: spray booth and finish what I have learned this year

Post by tippie53 »

here is one from final buffing
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John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Stray Feathers
Posts: 677
Joined: Sun Sep 08, 2013 11:39 pm
Location: Ladysmith, BC

Re: spray booth and finish what I have learned this year

Post by Stray Feathers »

What a gold mine of helpful information! Thanks for sharing your expertise. I realize I am (with earlier advice from you and others) gradually refining my process to pretty much match this, and today's post helps affirm that. I am just now buffing out a 12-string OM and looks like I am "on track". I just need more practice if I am to produce results like your beautiful guitars. A really helpful tip about the layers of masking tape, and also about spraying Mohawk out of the can. Bruce W.
tippie53
Posts: 7011
Joined: Fri Mar 03, 2006 7:09 pm
Location: Hegins, Pa
Contact:

Re: spray booth and finish what I have learned this year

Post by tippie53 »

the one thing that you have to learn is the feel of polishing. I can say that it isn't so much what you put on as much as it is what you let on. Learning to read the surface to know when you are truly level and flat and how to do body and fender work , by that I mean doing the drop fills to get this perfect.
Buffing out is another skill that takes feel and learning when to keep going and when to stop. Finish work takes skill in learning to read the surface but you can master this pretty easy just keep working . Learning what fillers work best and what polishing compounds give you the best results. The more you do it the better you get.
have fun learning and glad you found this helpful
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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