I once tried to get into airbrushing. Or rather, there were things I wanted to paint, and an airbrush was the best way to do it. I wore a respirator mask and bought a cheap bathroom fan to exhaust overspray and aerosols, but it didn’t work very well.
I didn’t have a well-ventilation workspace, and couldn’t get to one easily, and so I ultimately gave up.
16-17 years later, I want to get back to it. Naturally, I’ve been thinking about ventilation and filtration.
Tl;DR: Let’s say my DIY benchtop airbrush spray booth will have a 12″ x 24″ (2 square foot) filter size. What should I be looking for in a blower fan?
Where I’m Coming from
Airbrushes – by their nature – atomize paint particles. Paint will end up on whatever it is you are painting, all around whatever you are painting, and suspended in the air.
An airbrush paint spray booth is basically a benchtop hood that helps to contain overspray and keep fine particles from entering breathable air.
You can airbrush without ventilation, but I don’t want to. Ideally, a benchtop airbrush spray booth will allow me to paint what I want, whenever I want, and almost wherever I want to, with minimal prep or setup. That’s the goal.
All brands of hobbyist-grade paint booth equipment advise against use with fumes, solvents, or flammable sprays. Special explosion-proof fans are needed for use with flammable solvents or particles.
I intend to use acrylics, as opposed to lacquer or other flammable solvent-based paints.
I couldn’t find any appealing store-bought products, and so I decided to go the DIY route. I quickly hit a major snag as I realized I know nothing about blower fans, which would be at the heart of things.
Hobby Benchtop Airbrush Spray Booth Models
Amazon is filled with benchtop airbrush spray booths, such as this Master brand setup for under $150. I have seen the same portable spray booth product under different brands, and there are many variations of it.
There are good reviews for these products, and bad, but I ultimately question how good they can really be.
This model draws 25 watts and moves 4 cubic meters of air per minute, which converts to ~141 CFM.
Its workspace measures 16.5″ wide x 19″ deep x 13.5″ high.
The portable airbrush spray booth has a replaceable 2-layer fiberglass-type filter that measures 16″ wide x 7-1/4″ tall x 7/8″ thick.
It also has a rear exhaust fitting for a dryer vent connection. Some other models come with a hose that exhaust through the gap of a slightly opened window.
Paasche, an airbrush company, has a USA-made HSSB-22-16 benchtop hobby spray booth, for $327 as of the time of this posting.
It’s available at Amazon and ships in knocked-down screw-together format.
The HSSB-22-16 moves 270 CFM of air and has a working footprint of 22″ wide x 20″ deep x 16″ tall. I have seen some complaints about the actual benchtop footprint being deeper to accommodate the fan exhaust.
The filter size measures 17″ x 8″ x 1″. Amazon reviewers complain about the quality and thickness of the replacement filters.
It also has a 4″ dryer duct connection for directing the exhaust. No ducting is provided.
CFM is important, and so is the size of the spray booth opening. The filter size and thickness is also important.
The further away you get from the filter, and the larger the opening of the box, the lower the fpm rate will be.
System restrictions, such as once a filter starts to collect particles, are going to increase the static pressure and drop CFM and airspeed.
Paasche also offers two versions of the Masters-style portable airbrush spray booth – the HB-16-13 for which no airflow metrics are given, and the dual-fan HB-16-2F. There is also the HB-16-TT on Amazon, but it’s unclear how it’s different.
From what I’ve read about ventilation hoods in the past, 100 fpm is a good target.
The Masters-style airbrush spray booth is priced at $130 to $200, depending on the features you want. If you want a window exhaust nozzle and LED lighting, those kinds of features drive up the price.
The Paasche USA-made spray booth seems to offer more, but it has a large footprint and replacement filter availability can be a problem.
I have learned my lesson about getting less popular dust extractors and air cleaning products before.
More Professional Spray Booth Options
This is the Paasche BBF-2-T1, with a 12″ non-sparking blade fan. It has a working dimension of 2′ wide x 2.6′ deep x 2′ tall and is rated at moving 1000 CFM of air.
It meets OHSA, NFPA, and EPA regulations, and needs to be assembled and hardwired by an electrician. The price is $1,450.
This is the Cook Manufacturing table top paint booth, priced at $1,350.
It has a 12″ tube axial fan, manometer, and also meets or exceeds OSHA and NFPA 33 requirements. The user manual references steps needed for user compliance, such as the installation of a grounding rod and exhaust clearance considerations.
The smallest model has a working width of 32″, depth of 18″, and 36″ height.
Looking at Cook Manufacturing’s brochures, their 1HP single-phase 12″ belt-driven tube axial fan delivers 1600 CFM.
This is the Sentry Air “portable” benchtop spray booth, priced at $3,502.
This is a ductless system with HEPA filter and 10 lbs of activation carbon for filtering VOCs.
The working dimensions are 30″ wide x 23.5″ deep x 24″ tall.
Sentry Air says their approximate air velocities are 100 fpm with the pre-filter and HEPA filter, and 60 fpm with the pre-filter and heavy-duty carbon filter.
Their 3-stage filtration includes a MERV 7 pre-filter for overspray, HEPA filter for fine particulates, and activated carbon for odors and VOCs.
The Best DIY Option so Far
There are few appealing options in the $100 to $350 price range, and nothing else until you get into $1000+ territory,
All of this has been driving me towards a DIY-type approach.
So far, I found one good example to learn from.
I came across Vent Works, a small company or part of a larger company, that offers plans for a DIY benchtop spray booth.
They don’t have plans per se, but they provide enough how-to info to help make things easy. They also sell some of the hard-to-DIY parts, such as a sheet metal filter holder, a blower fan mounting bracket, and square to round exhaust duct adapter.
Their design is centered around a standard-type 12″ x 24″ x 1″ furnace filter.
The blower fan they tested and recommend for the setup delivers 265 CFM at 1500 RPM, and with a nearly 2A power draw.
I have been looking into the fan selection, and that’s where I realized I need some help.
Blower Fan Options
Vent Works recommends the Dayton 6FHX9 (via Grainger). This is the model they designed their mounting brackets and adapter around.
We chose this Dayton blower because it is quiet and powerful. We ran comparison tests of many different blowers and fans, the Dayton 6FHX9 was the quietest, it held up the best against static pressure and won the best overall performance out of any other blowers of similar power
Dayton 6FHX9 Specs
- 5-1/4 in blower wheel
- 2-7/8 in blower wheel width
- Shaded pole motor
- 115V AC, 1.95A at full load
- 1610 RPM
- Sleeve bearing
- 265 CFM at 0″ SP
- 212 CFM at 0.3″ SP
- 135 CFM at 0.5″ SP
The size and style of filter is going to affect the static pressure drop.
Doing more research, I came across a few DIY projects where designers went with higher-rated blower fans, and in one instance a two-speed blower fan.
Here’s a different blower fan, via Grainger. Actually, I came across a lot more, but this seems like a good example.
Dayton 1TDR7 Specs
- 6-3/16 in blower wheel
- 1-7/8 in blower wheel width
- Permanent split capacitor motor
- 115V AC, 1.35A at full load
- 1650 RPM
- Ball bearing
- 485 CFM at 0″ SP
- 425 CFM at 0.3″ SP
- 375 CFM at 0.5″ SP
- 215 CFM at 0.8″ SP
This one has a different type of motor, larger blower wheel, ball bearing, and higher CFM ratings.
Here are specs for a dual-speed fan:
Dayton 1TDT7 Specs
- 6-1/4 in blower wheel
- 3-3/16 in blower wheel width
- Permanent split capacitor motor
- 115V AC, 2.00A/1.54A at full load (high/low)
- 1430/1060 (high/low)
- Ball bearing
- 542/409 CFM at 0″ SP
- 480/375 CFM at 0.3″ SP
- 450/348 CFM at 0.5″ SP
- 358/270 CFM at 0.8″ SP
There is another model with specs closer to the blower Vent Works recommends:
Dayton 1TDR3 Specs
- 5-1/8 in blower wheel
- 3-11/32 in blower wheel width
- Permanent split capacitor motor
- 115V AC, 0.77A at full load
- 1640 RPM
- Ball bearing
- 273 CFM at 0″ SP
- 210 CFM at 0.3″ SP
- 135 CFM at 0.5″ SP
This model has comparable CFM at 0.3″ and 0.5″ SP (static pressure drops), but draws less than half the power.
Blower Fan Questions
Is a 265 CFM fan really the best recommendation when there are others in the same price range?
There are other brands of motors, but I started looking at Dayton at Grainger to better understand what to look for and why.
From what I’ve read, permanent split capacitor motors are more efficient than the shaded pole motor model recommended by Vent Works.
What’s the downside of a motor consuming less power to put out the same air volume?
Maybe there were cost considerations – Vent Works’ project and documentation is several years old now – but unless I’m missing something, more airflow is better, especially if you can get it without stepping up too much in size or cost.
More airflow usually means more noise, not necessarily just from a motor, but from the air movement. But more airflow means greater air speed, which means more particulates pulled towards and captured by the filter.
A DIY project gives me the freedom to select different fan sizes, such as 10″ x 20″, 16″ x 20″, 14″ x 24″. Or I could order filter material to cut and install in a custom frame, although that seems like too much of a hassle.
I like this option, rather than spending $125 on a small-filter consumer product or $350 on a sheet metal booth that seems too deep for my space.
It seems that filter size, workspace volume (or cross sectional area at least), and blower fan selection are all inter-related.
Buying a larger blower than is needed might create too much noise, or potentially other issues. But, I would think having overhead can help make up for any restrictions that might come up, such as if step-down ducting is needed for a window exhaust (or filter box if exhausted to the room).
100 fpm is a good target, but are we talking about right in front of the filter, at the center of the box, or at the opening?
Let’s say we have a simple box with 12″ x 24″ filter. Not taking into account static pressure drop, this would suggest a blower fan with 200 CFM is need – minimum. Will corrugated ducting be used for the exhaust? Will there be any sizing adapters? What type of filter will be used?
What CFM will be needed to maintain 100 fpm at a distance of 12″ from the filter? What about a distance of 18″?
The store-bought boxes shown above have relatively small filters. What happens when one needs to work closer to the opening of the booth, such as when working on the front of a larger part? Will there be enough air speed to capture overspray?
I don’t know what I don’t know. All I know is that I don’t like the size or specs of the hobby models, and I lack the need, space, desire, or money for any of the more professional products shown I’ve seen.
So what do I need to know to competently choose a fan for this?
As an aside, can a DIY spray hood designed to collect airbrush fine particulates be useful for small dust-generating tasks, such as sanding, cutting, or grinding with a rotary tool? Or maybe as a fume hood for nuisance-level 3D printer odors?
Again, this is all in the context for what could be considered inert materials. Spraying with solvents or flammable materials require special explosion-proof motors or setups. A real paint booth, as opposed to a hobbyist airbrush benchtop hood, might have a tube axial-style fan and special setup requirements.
Even More Options?!
There are all kinds of other exhaust fans – shown here is an inline AC Infinity Cloudline fan with 6″ duct size, EC motor, PWM speed controller, ball bearings, and 402 CFM specs.
AC Infinity seems to produce consumer ventilation products for cooling AV cabinets, grow tents, and general use.
Something like that might be easier to design a DIY paint booth cabinet around, and for less money than a traditional squirrel cage-style blower fan.
With the AC Infinity products, they also make charcoal filters (here’s the 6″ filter) that might work well for controlling nuisance-level odors (such as from 3D printers??).
But how well do EC fans handle restrictions such as filters, compared to PCS or shaded pole motors? I don’t think these products would handle filters very well, but I also don’t know as they only provide free air CFM specs (at least from what I have seen so far).
They also have less silent models (shown above) at lower pricing. This is the TD-150, with 6-inch duct size. it delivers 293 CFM, operates at 2289 RPM, and draws 0.54A at max load. It’s priced at ~$170.
Soler TD-150 Specs
- 6″ duct size
- 115V AC, 0.54A at full load
- 2290 RPM
- Ball bearing
- 295 CFM at 0″ SP
- 242 CFM at 0.3″ SP
- 204 CFM at 0.5″ SP
Whereas the AC Infinity inline blowers seem to lack clear CFM ratings at different restriction figures, Soler has data going up to 1″ of static pressure drop.
This type of product would require wiring, similar to the squirrel cage-style blowers discussed above. But, it should be easier to install, given the round duct ports, although its inline nature would require more care.
There’s a catch – greater airflow requires larger duct sizing, which will complicate things. It also requires inline connection, which will be difficult to accomplish without increasing the size and complexity of the installation.
Soler advertises their “mixed flow” fans as delivering a balance between low noise level, medium-high air volume, and medium-high static pressure.
But, the “classic centrifugal” fans listed above cost less and move more air.
The popular “portable” solution seems a bit gimmicky, with fold-out panels and retractable power cord. There are a couple of more premium options, but I’m not convinced about any of them.
I’d like to go for a “build it once and have it last 10+ years” type of solution, and am open to suggestions.
The DIY route is appealing, but I cannot find the middle ground between “throw some parts together” and “advanced HVAC and engineer skills required” types of paths.
Trial-and-error is possible, but would quickly get expensive and time-consuming.
I’m hoping to land somewhere in the $150 to $350 price range.
And yes, I know I’m overthinking things – I have seen DIY paint booths with nothing but a filter taped to a box fan and placed in a cardboard enclosure. But I would ideally like to be to paint and then work on other projects in the same room without worrying about what I might be breathing in.
I am willing to put in more research time, but figured it wouldn’t hurt to ask for help.
With all that said, it comes down to one question:
Let’s say my DIY benchtop airbrush spray booth will have a 12″ x 24″ (2 square foot) filter size. What should I be looking for in a blower fan?
What style (e.g. inline or squirrel-cage/centrifugal)? What type of motor (e.g. PCS)? How much CFM?
Which will be easier to mount and adapter to 4″ dryer vent-style connection?