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I know it is probably a dumb question, but still I wanted to ask if the initial off-gassing process can make a small room or closet unsafe to contain lets say two fresh finished guitars and a small heating unit or dehumidifier?

I am asking because i plan to spray outside, but in the upcoming winter I have to find a place to hang the guitars. Winters can reach over 90% humidity here.

Thanks, Gorjan

Hey Gorjan,
I would not bring a freshly sprayed guitar into my house. I would especially not put two of them in a closet. First, the fumes are toxic, second, they will take a long time to gas off if the gasses are trapped in the closet. If you have a way to vent the fumes outside, then it might work. Otherwise, I would not do it. Nitro needs to gas off, as you know. This is why people build drying boxes for them to speed the gassing off process. If the gasses are allowed to accumulate, even if they are just sitting on the surface of the guitar that is being stored face up, it will slow the process. Air circulation is important for drying. If you have a problem with blushing because of the humidity, add some retarder to the mix and it will clear right up. Blush happens because moisture is trapped under the surface of the nitro when it flashes off and skins over. Slowing this process down will allow the trapped moisture to escape and eliminate blushing. I have sprayed rattle can nitro during a rain storm in June. I got some blushing, so I hit it with some Jet blush remover, which is just retarder and solvent in a rattle can, and the blush faded away before my eyes.
I would never bring a freshly lacquered box into my house under any circumstances. You shouldn't either.

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http://www.CostaGuitars.com
PMoMC

I agree. The fumes are not good for your health.
As far as drying goes, humidity is mainly a concern when the spraying is actually taking place. After that, the main consideration is ventilation. I use a box fan on the guitar in my unheated shop building, with the windows open. I don't worry about temperature unless it gets way below freezing.
The drying of lacquer is about ventilation, much more than temperature or humidity. If I need to, I will spray at 25 degrees F.

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John

thank you for your answers. I just cant afford to build a booth, even though i have the space. so i decided to spray outside, but than i guess i will have to build a special room that will be ventilated and where i can hang guitar (if i'm lucky ill turn it into a spray booth in the future)

If this will help you, I'll tell you what I did. I have a big garage, with three car doors in front, and two casement windows in back. The windows are screened. I sprayed stew-mac rattle can lacquer outside, and stood just inside an open car door for a minute or two until the lacquer had flashed off and I didn't need to worry about bugs. Then back outside for a few minutes to let the initial gasses dissipate a little more. Then I carried my neck and body parts to hooks just inside one of the open screened windows. I hung them there, and left the big car door open for a few hours. I did this daily until I built up my desired number of coats. Even though I was outside, I always did it with a respirator mask. Even though I worked mostly outside, or in an open garage door, the odor was sickly-sweet in my garage for about thirty minutes after each spray session. I did three or four sessions per day. Definitely DO NOT bring these pieces into your house while they are out-gassing.