Thursday, February 9, 2012

My DIY spray booth

It's my day off from my regular job tomorrow (sound of high fives all round). Thursday also marks the first time I will use my airbrush 'in anger' so to speak.  I'll be able to tell you more about my airbrush experience tomorrow, come-what-may.  It'll either be a triumphant report of success or keystone cops style tragi-comedy, but either way I'll let you know how I got on...

In the meantime I thought I'd talk about the spray booth I made specifically for the airbrush and share a few pics too.
What's a spraybooth?

The purpose of a spray-booth (hobby, commercial or industrial) is to catch overspray and to filter and expel potentially harmful nasties that are used in spray paints.  Most spray booths are essentially a box with an extractor fan (or fans) and varying grades of foam, paper or cardboard filters. Quite apart from the potential 'mess' airbrushes can make, even acrylic based paints (which is what I'll be using exclusively) can have microscopically sized harmful particles in them so I think that having a spray booth is a good idea.

Before I made my own last month, I shopped around for a good decent sized hobby spray booth.  I couldn't find one.  The two models that were vaguely within my price range seemed a bit pokey for what I wanted.  I felt I needed something with a bit of elbow room so I decided to make my own.  This decision wasn't a complete jump into the unknown as there have been several precedents set (just search for 'diy spray booth' on youtube or do a google search) but my main inspiration came from a tutorial video I downloaded from CoolMiniOrNot called 'The 7 Day Army Painter with Brandon Palmer'.

Brandon runs GMM Studios and he spends all day, every day painting armies for war gamer's. That's his job! How cool is that!  Anyway, the first half of the video concentrates on Brandons, tools, materials, work-space and processes.  This for me, is worth the price of the download by itself, it's that informative.  The main thing for me though was his thorough and eloquent 'show and tell' on the different airbrushes he uses, followed by why and then how.  Very good indeed.  During that first half of the video Brandon also shows the spray booth that dominates his work space, a home-made 4ft by 2ft by 2ft plywood monster.  Frankly it looked indestructible.  The point was, I thought, if he can do it, so can I (albeit on a slightly smaller scale).

Building the spray booth

The box

I knew I didn't really want to 'build' anything.  My carpentry skills are non-existent and I wanted something ready made that I could bolt an extractor fan onto with the minimum of fuss.  In the end that's exactly what happened although it took me a while to find the right size and shape box that I wanted.  After disqualifying a lot of also-rans I settled on a huge plastic storage box from the Swedish cathedral of furniture dreams, that is Ikea.  It's called a SAMLA storage bin and it retails at £17.99 here in the UK.  The advantages to me were it's generous proportions (79cm x 56cm x 42cm) compared to the cheapest hobby spray booth (42cm x 48cm x 34cm), it's transparency (to let lot's of light in) and it's shape (a nice angled opening, almost like a commercial spray booth).

The fan

My next purchase was an extractor fan.  Now I don't want to bore you too much with the mathematics on this but extractor fans are rated by how much air they can move.  The generally accepted measurements are in CFM (Cubic Feet per Minute) M3/hr (Meters Cubed per Hour) or M3/m (Meters Cubed per Minute).  Thrilling I know. So my goal for this phase of the operation was to buy something that gave me the maximum extraction for the lowest price.  Specifically, I wanted a fan that gave me at least the extraction of a small shop bought hobby spray booth (about 3M3/m).

Again I shopped around on a couple of hardware sites and I found what I wanted, the dynamically named 'Manrose Kitchen Extractor with pull cord' (£24.83).  This fan has an extraction rate of  3.83M3/m. Perfect! I got this fan from Screwfix with 3m of ducting hose (£4.43) and a fitting to attach the ducting house to the fan (£6.99).  The extractor didn't come with a power cord so I used one from a long-dead PC and wired it up myself.  The pull cord on the fan meant that I didn't have to do any other fiddly electrical switch stuff to switch the fan on and off.

Putting it all together

To fit the fan to the bin I drilled out the appropriate sized circle at the top of the bin and then simply screwed it on. I decided to make it off centre as I'm right handed and I'll be spraying to my left, so I figured the fan would catch more over-spray that way.

I also mounted the fan in the 'roof' of the box as I'd heard anecdotally that it's not a great idea to put the fan directly in front of the airflow of the airbrush.  This is due, rather scarily, to potentially flammable elements in the spray paint igniting if your fan should 'spark' and then cause a massive airbrush induced fireball through the back of your fan! Ok, the words 'massive' and 'fireball' are mine but fire 'anything' doesn't sound good, so even though after a thorough search I couldn't find any examples of this 'ever' actually happening, I decided that it's better to err on the side of caution where safety is concerned.

The last thing on my shopping list was a filter to tape over the face of the fan.  After much deliberation I decided to order the filter for a regular hobby spray booth which I got from ebay (£4.50)

Putting a lid on it

I'm going to use the top of the lid from the SAMLA bin as a kind of shield that will also hopefully direct more airflow through the fan(?).  I'll also probably put down some newspaper in the base of the booth to soak up any larger overspray.  The ducting hose connected to the back of the fan will be going through an open window so it exhausts any harmful stuff outside.

In Summary

So all in all I've spent under £60 plus a little time and effort to get exactly what I wanted.  Of course, I don't 'really' know if it's going to work as well as a shop bought model but I reckon it's way better than nothing (which is what I had before this project). Incidentally I'll also be using a proper face mask with filters in conjunction with the spray booth to provide another layer of defence against spray paint nasties.

Apologies for the very long post and well done if you'd made it this far! If you have any questions relating to this project let me know in the comments. Maybe you've made something yourself that you can tell me about. Maybe I've made a fundamental mistake that you need to point out!?

In the meantime I enclose some pics and part with a promise to let you know how my first foray into airbrushing goes tomorrow!


Side view and ducting hose - Kroot and 1/2 a devilfish for scale

Front view

Looking up without 'shield"

Looking up with 'shield'
The Fan! - Bore people to death with airflow measurements!

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  1. VERY nice. I've been hemming and hawing back and forth on whether to break into airbrushing figures, even just for custom basecoats, and this is a nice push for me to do so. the spray booth you made is a nice price-point and solid. Nice tutorial :)

    - Tim

    1. Hi Tim, many thanks. The thing that finally pushed me towards the airbrush was the weather here in the U.K. It seems like it's wet and/or cold about 9 months of the year... In the (indeterminate) future I want to put together a post or two about the voodoo of compressors and airbrushes too.

  2. Nice article...
    We have the enviable task of working on a larger scale. If only we could offer a spray booth for $60!!

    1. Thanks Chris, I jus visited your website. That's a proper 'grown-up' spray booth! Reminds me of the line from the Crocodile Dundee movie when he's visiting New York and faces up to a would be mugger "That's not a knife [he pulls out a large bowie knife]...THAT'S a knife..."

  3. Great article, I've been thinking about doing this (with the Samla box) for a couple of weeks and glad to find someone else thats done the same thing.

    I work with enamel paints and I'm also concerned about the potentially flammable fumes coming into contact with the fan motor and causing an explosion (!). Did you look around at any other (cheap) fans where the airflow was kept separate to the fan motor?

    Other DIY spraybooth's I've seen have all mentioned keeping the ducting as straight and short as possible to help the airflow - maybe you could make yours a bit shorter and a more direct/straight route to the window...?

    Do you have any more photos, or a follow-up post to let us know how its going?

    1. HI James, thanks for your kind comments.

      I don't work with enamels at all ( I sleep in the same room that I airbrush in!) but I believe you should be searching for a 'non-spark' fan to avoid horrific paint based combustion...

      I remember seeing the Samla bin in Ikea and doing a double take, it was just what I needed! It's been providing excellent service to date and it's dead easy to clean too. There has been lots of interest in this post and you've definitely got me thinking about a follow-up so watch this space.

  4. Thanks for this post! I have currently been spraying into a cardboard box with a hole in the top and stuck 3/4 of the way out my window onto my fire escape. Not very efficient!

    I am going to try your project :)

  5. This looks like it would be perfect for the kind of small-object painting I do. One possibly "durrr" question: you casually mention drilling the hole for the fan. That looks like a sizable hole! What method did you use? Thanks for this writeup