New HVLP Spray Gun System #2: Spraying Booth and Solvent Issues

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Blog entry by HappyHowie posted 11-27-2016 01:47 AM 1428 reads 0 times favorited 4 comments Add to Favorites Watch
« Part 1: Unboxing of New Fuji Semi Pro 2 System Part 2 of New HVLP Spray Gun System series no next part

I have a tendency to jump in with both feet even though I believe I over analyze new purchases. Let me explain. I decided that I want to have better experiences in finishing my woodworking projects; including oil based finishes. I purchased recently a nice Fuji spray system. I bought the Fuji Semi-Pro turbine based spray. It is the best that I could afford at this time. I believe it will do a great job for me as I gain experience in using an HVLP spray gun. I have sprayed paint before in my home’s basement when I refinished it plus two years ago I sprayed the entire indoors of my daughter’s new fixer upper home before she moved in. What I am saying is I am familiar with spray systems and techniques. However, this will be my first real experience in using an HVLP system for woodworking projects.

Certainly, is the weather was good I can setup an area outdoors to do my spraying. This now is winter time. It is cold outside; too cold and windy for spraying finish. My woodshop is my 3-car garage. I have a nice electric heater with an insulated attic above. I can hit a nice temperature, if required, for spraying finish.

If all I was going to spray was waterborne finishes or paint, then a simple box fan with an furnance filter in front would probably suffice. However, that was not my primary reason for purchasing a turbine based HVLP spraying system. I want to use oil based or solvent based finishes like Shellac. I cannot rub or brush on Shellac well enough to be satisfied with my results. I have heard the 360 Woodworking guys talk about their Shellac methods of application. Glen Huey says he only sprays on his Shellac. I figure that will be my only successful method.

Things would be good, I think, for building a “tear-down” spraying booth in my garage except for the cost to purchase a combustion proof fan. I did not realize that these explosion proof fans are that expensive. The only reference I have found was a DC powered boat exhaust fan. Some woodworker stated that he was using one of these in his spray booth. Was it here on that I read that entry? However, he did not know the fan’s CFM rating. He says he gets enough air movement, but I am not sure. I certainly would not be out of that much money if it didn’t work for me.

I just would like to know what other woodworkers are using for fans; like manufacturer and model for their solvent based finish spraying. If there is someone out there that is spraying oil finishes or solvent based finishes, I would like to know what they are using for a combustion proof fan.? What was the less costly fans that they found for their booths?

Popular Woodworking spray booth article…

-- --- Happy Howie

4 comments so far

View EarlS's profile


3405 posts in 2948 days

#1 posted 11-28-2016 12:29 AM

If you are concerned about having an explosive atmosphere, you should be even more concerned that you are breathing high concentrations of solvents. For some background, I am a chemical engineer that builds chemical plants. Typically, explosive limits for most solvents are in the percentage range, not the ppm range. Acetone is explosive between 2.6% and 12.8% (that is how much acetone is in the air by volume). That is A LOT of solvent evaporated in the air. Consider how much solvent is in the shellac or whatever finish you are using. Chances are there is not enough of it in the entire container to get the the lower explosive limit in your shop. If you have that much acetone in the air in your shop you need to ventilate the area with fresh air so you don’t get “high” and possibly risk health problems.

You can look for material safety data sheets on the various solvents and they list exposure limits as well as upper and lower explosive limits. Oil based finishes aren’t explosive since the oil isn’t as volatile (easy to evaporate). If you want an explosion proof motor, look for a Class I, Division I motor. They are available.

It is hard to give general tips on this kind of subject. I would open the door or window and pull fresh air in with a fan that has a furnace filter on it and then open a window and put a furnace filter in it as well so that any finish winds up on the filter and not the screen. That is how I set up when I spray oil based finishes.

I don’t spray shellac as it dries almost as soon as it leaves the tip of the HVLP (I have a Fuji) and you wind up with a mess that has to be smoothed out by brushing on another coat. The second coat dissolves the first coat and should smooth it out. I use super fine wet paper to finish out shellac. I also don’t use shellac for anything that will see a lot of use since shellac isn’t very hard or durable.

Sorry for rambling, hope it gives you some things to think about. Post a reply if you have questions and I will check back.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

View HappyHowie's profile


473 posts in 2545 days

#2 posted 11-28-2016 04:03 AM

Thanks Earl for your reply. Whenever I meet a chemist professor or chemical engineer I tell them “they have my immediate respect”. It was my physics that got me through my first year of chemistry in college. You know, Ideal Gas Law, etc… Chemistry for me was like magic stuff: you take this and mix it with this and abracadabra, puff, and you get this! It did not seem to have a formula or equation like in physics. It was like my memorization of the integral equations inside the cover of my calculus book.

This membership on Lumberjocks has been a great experience for me. As an new but enthusiastic woodworker who wants to learn and gain experience, the advice that I receive from more experienced woodworkers who are willing to give advice is truly invaluable to me. This site has been an awesome experience.

I am glad that you gave a description of how you operate your shop for spraying. Your description is better than most others that I have seen in photos or in written in paragraphs. Now knowing how important it is to you to have not only air blown and filtered out of the shop. but to also be blown in and filtered I will attempt to replicate that in my design for my garage teardown spray booth operation.

All of what I know about woodworking is what I have read and gained in practice. I am a willing student. I have tried to accumulate and read from a good library collection as well as from subscriptions to leading magazines. When I read and listen to Jeff Jewitt who says if you are going to spray solvent based finish then you will need a combustion proof fan, I take this professional finisher for his word. I notice though that he (or others) never say why exactly, or what the consequences may be except that the innuendo is that you might start a fire or have an explosion. I also notice that when someone is saying they are building a spray booth and another gives a warning about spraying oils or solvents, the answer is “oh, I am only spraying water based finishes” so I do not have to worry about nasty solvents.

I suspected that the percentage of solvents in the air would be low for the spraying I would do on woodworking projects. I surmised that spraying the body of an automobile would be an entirely different experience. It would take a tremendous more amount of material to spray an automobile than it would take to spray say a dining table, for instance.

I do wear a respirator mask. The masks I wear is the 3M product that can be found on the Home Depot or Lowe’s shelves. I think I am buying the correct filter pads that fit within the device. I also keep those pads inside a sealed baggie when not in use. So I am hoping I am taking care of my lungs in the correct manner.

I have lost a house to a fire many years ago. I do not want to have that experience again. The memories and troubles of that experience are ones to avoid. If it takes several hundred dollars or a thousand to fire proof my hobby, then I will do it if I am compelled to spray solvent finishes. Otherwise, I will wait for Spring and Summer seasons where I can spray my projects outside.

I have watched Glen Huey explain how he sprays Shellac instead of trying to brush or rag it on his projects. I have tried to brush and rag Shellac. I do not have the knack to do it right, or satisfy myself let alone anyone else. I may not even be able to spray it well. I won’t know until I try. It certainly seems that this experienced woodworker has used a lot of Shellac for his projects. I have also taken an online lesson from Tom Mclaughlin, a professional furniture maker. I have seen his instruction for spraying tinted Zinsser dewaxed shellac sealing coat sanding sealer on his projects. It seems like a good product and method for sealing my woodworking projects. It think that I should at least be trying to finish some of my projects with this same time tested or used finish product.

I could continue to use varnishes like Danish Oil and General Finishes ARM-R-SEAL. I get good results. It just seems that I should expand my experience beyond what I have done. How else would I learn beyond what i have? I also want to learn what Charles Neil has to teach by practicing his methods in my shop..

Thank you again, Earl. You did not ramble. You were very instructive. I know I get too verbose. It is just that I like to get my thoughts out. Maybe too much. I know I am using a shotgun with my words instead of selecting a rifle. I guess I am hoping I get more hits with use of more words. Best wishes. Howie

-- --- Happy Howie

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