Moose has been pondering the design and build of a DIY paint booth. Being a professional engineer, Moose intends to design it based on a thorough understanding of the underlying technical requirements that make for a safe, effective and moose-thrifty design. Which means, re-acquainting moose-self with basics of aerodynamics as well as flammability. If there are any professional aerodynamics and/or flammability experts on here, would like to read your comments. Please note, Moose has studied commercially available hobbyist booth designs, reverse-engineering their capabilities for air flow and filtration, and reviewed various state & federal codes pertaining to paint booths, as well as ACGIH guidance. Thus far, Moose is not convinced that any of the reasonably priced commercially available booths are very good -- IMHO (in Moose's humble opinion). This is really an experiment to satisfy Moose's desire to understand how to design the best possible paint booth (at a reasonable cost). If your paint booth works great for you, meets all your needs, hasn't exploded or put you in an early grave, awesome! No critique from Moose here!
Hi Moose, Here's an idea. Couple years back, I bought an airbrush. Not thinking ahead, I now had an airbrush, paint, compressor and no place to spray. But I did have a cardboard box, a 110V muffin fan, filter media for a compressor intake, hot glue and small led light. Necessity being the mother of invention I scabbed together this Mickey Mouse spray booth. It worked so well, this is all I use for airbrushing. As it vents inside I use water based paint ONLY. Rattle can spraying is done outside the house. Do not use this booth for solvent based paint!
With having to get so much delivered we should have plenty of those boxes. The filters are readily available. There's some nice LED undercabinet lights. And the muffin fans are readily available for a low price. So you box is easily built for much less.
@hawkdriver Thank you for the information and photos! Nice, simple design. Moose, being an engineer, wants to understand what aspects of a design allow it to function for the purposes one intends. Presumably, the kind of set up you have provides enough air velocity to ensure that the visible over-spray paint is pulled into the filter. Since you are not using enamels and/or aerosols, the "poof!" issue is not a strong concern. Questions that comes to mind: 1. Are paint over-spray particles that are smaller than what you can see being aspirated because the air flow is insufficient?, 2. Can paint over-spray particles, that might pass through the filter material, build up on the fan, eventually to a level that could be flammable or combustible by the fan? One of the issues for hobbyist-sized open faced paint booths is the air turbulence that the user causes due to their size and proximity to the paint booth opening. From what Moose has read, this can be a significant issue, requiring significantly higher air velocities than larger booths, just to over-come the turbulence. Although flammable enamels and aerosols might not be used in the paint booth, the paint itself can build up on the fan and become a safety hazard through fan-related ignition. Filters, no matter their efficiency at capturing paint particles, still allow some paint particles through. So how does one deal with paint build-up on a fan not designed for this kind of application? Another thing that Moose is trying to better understand is the relative health safety of acrylic paint particles. At low enough levels, they may not be health issues at all for most people, may be irritants for some, and exasperate health issues for others. What concentration levels are considered acceptable AND how to determine what maximum concentration levels one could ever experience for a given design? After writing all this, Moose just wants to forget about paint booths and go back to running trains...
Moose, You would be surprised how little excess sprayed material goes past the target item with an airbrush. Granted, there is some, but that media captures more than you would think....sure surprised me. I check the fan blades often for paint residue and there is next to none. If you are going to spray large items, with a gun, this booth will not work. But, your concerns are well founded. Al
@hawkdriver Awesome to read that, good sir! Moose has no practical experience with paint booths, so definitely helpful to read that you are not getting a lot of paint passing on to the fan. Thank you. One of the nice things about your design is that you are not trying to exhaust the air through a hose or similar, as those muffin fans are not designed to push air through hoses, ducts, etc. Having good ventilation in the area where the booth is located and not using harmful substances are essential. Moose intends to use the "some day" paint booth in a garage, but is still considering duct work to vent exhaust to the outdoors if necessary. The ducts, any bends in the duct work and the filter(s) all contribute to static pressure that effects fan performance... Blah blah blah, rambling again...
Amazon has a good choice of muffin fans. 120mm square, AC and different power levels. For intake and exhaust. About $18. I would settle for a quite low volume exhaust with a filter available at hardware stores. https://www.amazon.com/gp/product/B009OWVUJ0/ref=ox_sc_act_title_2?smid=A2AW0W4FKP16S5&psc=1 Richard
While at the hardware store get some fender washers to hold the fan to the box. And a good role of boxing tape.
I made one.... Haven't used it yet so no real info on that but it moves a lot of air. Also I'll only use acrylics. I do have a supplied air mask and compressor that I used with very toxic car paints. It supplies you with outside air to the full face mask. Won't be using it though. This would be easy to duct outside with the hose. With the two filters I don't think there would be much paint buildup on the fan but..... ..... if there was the fan isn't that expensive (less than what we spend for most items in the hobby). Also since the fan is in the air stream I would not use this with any paint that could be flammable. More on the build here ..... http://1fatgmc.com/RailRoad/Misc/page-4.html Not as cute as the commercial ones but I feel it will be practical for me at a cost of less than $50. Sumner
@Sumner Thank you good sir for the information, photos and web link! Moose has seen your paint booth before and is actually part of the inspiration for Moose to build instead of buy...
@BoxcabE50 Thank you for the information and link! Questions: 1. How does the duct connect to the fan? 2. What is the diameter of the duct?
All nice ideas and there could be more. After all we railroaders are innovators. I expecially like the storage tub because can be closed up, it can take the humidity and stored away without worry. And I have a few of several sizes.
1) There is an outlet which is part of the fan box. The ducting fits over that, simply held by duct tape. I used the metal foil style of duct tape, which does not dry out and come loose as does the traditional cloth style of duct tape. 2) It is the standard size of flexible aluminum clothes dryer ducting. I believe that is four inches. Safer and more durable. Allows plenty of exhaust air flow.
Well, Moose's foray into designing a paint booth has come to an end -- Mrs Moose ordered one for Moose birthday. How unexpected... Works for Moose! Moose does happy dance!
Back in the day I was an auto body painter. I also built car and starship models. I was tired of getting bugs and dirt in my paint jobs and I was not able to paint outside when it would rain… which happens here in WA quite a bit from fall to spring, and in the summer I didn’t want to stay inside building models… it was too nice out! So taking ideas from the paint booth I painted real cars in, I designed a down draft type model paint booth. There was a filter (automotive panel type) for the inlet at the top, and a fiberglass style (home furnace type) on the bottom. The fiberglass filter was taken apart and just stuffed under the booth in a little box. That box had a fitting on it that went to my shop vac, and I would put an exhaust hose on the outlet of the shop vac out a window. The air inlet was similar but I used an old hair dryer. This allowed me to get air flow at cool temps when I was spraying, then I could turn up the heat to bake/dry the paint faster. It took me a little while to figure out how to make it “positive pressure” so to keep the dust out, I did this by restricting the exhaust flow going out. The box was 12x12x12 and I had a rotating stand I made out of an old spice rack. There was also a lid that I could put over it after I was done to allow my models to dry in peace. it worked really well, it was made out of plexiglass which prolly was not the best ides as it collected dust from static. I solved this by painting more of the inside surfaces white, the paint shielded the plastic and no more (or at leas a lot less) dust. I don’t have any pictures of it unfortunately, that was back in the days before digital cameras. My ex and her new bf threw it out of the house when they were “helping” me move, it broke and I never rebuilt it. being a positive pressure device, I never had enough fumes concentrated enough to worry about a fire. I would also sometimes just use the hair dryer and not the vacuum as the vacuum was loud and the hairdryer pushed air quite well.
My only question is the exhaust from the shop vac. I have two wet/dry and they just exhaust around the motor. There is no ducting. Of course, I could just put it outside but being on the second floor that could be difficult. The one for the garage is simple so it may be easy to alter.
Engineer here as well. Albeit a building power engineer. But I digress. I built my own. Just took plywood and 1x's and framed up a funnel deep enough to easily put models in. Lined it with duct work sheet metal from Lowes, added a small 18" kitchen light in the top. I used a squirrel cage motor for Grainger and had a tin-knocker make a transition for me to accept a 3" flex exhaust. I pipe it over to a window about 10' away and made an outlet so I can lower the top of the window, wedge in the outlet when I use it. I wired it such that I can turn the light on independent of the fan so I can have it "lit" if needed when the fan is not running. I use cheap furnace filters cut to fit put in front of the fan inlet at the back of the booth. That sucker will pull the white off of rice and does a good job. Not a lot of thought went into the mechanics. Just creating huge negative pressure pulls the fumes out well. Just searched my albums and I, apologetically, have no photo of the booth. I'll try to upload one. I've built 2 of these the last 34 years. They've worked great.
