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The Homemade Spray Booth – Friend or Foe?

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spray booth with all four walls down

Deciding to Build A Spray Finishing Booth

After spraying projects on my driveway in Las Vegas, and having neighbors drive by and wonder what the heck I was doing,  I was initially relieved when I moved into a real shop.  I was all excited the first time I pulled the HVLP out for the first project, until I realized that this location wasn’t exactly ideal either.   There were three major problems to contend with at the new location that forced me to figure out how to spray indoors.

View of the outside front of my shop

First off, the driveway is on the north side of the building, and it blocks the sunlight.  That makes finishing difficult when you can’t see the finish being laid down.  Since I haven’t mastered spraying with my eyes closed, it poses some problems.  Although, I had the same problem in Vegas, depending on the time of year, and I was able to get decent results.  So, this didn’t kill the deal.

The second problem is what killed it.  Although difficult to explain, I hope the photo can help to show the problem.   The building is below grade and there is a wall along the east side of the property.  When the wind blows, it doesn’t just blow across and keep going, it blows in and swirls like a tornado against the building and the adjoining wall, picking up all the dirt and debris it can, then tossing it back onto my newly applied finish.  I can handle some dust nibs in finish, but this was ridiculous!

The final problem is the winter in Northern Nevada.   Low temperatures, rain and snow don’t mix with finishing.  According to General Finishes, snow isn’t the recommended weather condition for applying their product,  go figure!  So, I had some decisions to make.  I could go with hand applied finishes only or I would have to figure out how to spray inside.  Honestly, I like a good wiping varnish, but it’s just not the best solution to all finishing situations.  Plus it takes forever to cure compared to most spray finishes.

So, I decided to look into spray booths, and I was overcome with joy when I learned that I would need to take out a mortgage to buy a real one.  Through further investigation, I actually found two products that were perfect for my situation, but even at a much lower price than industrial-grade booths, it was just way too much for my budget.  Although I didn’t buy one, they are pretty cool and worth taking a look at – the blow-up one especially.  The other product is somewhat similar, but open ended, and it just wouldn’t work in my situation.  One of the problems with spraying inside the shop is the fact that I share the shop with my Dad, who runs a metalworking machine shop.  Because he uses solvents and such in his operations, I was worried about finish contamination, so an open ended booth could cause more problems than swirling dust.

I fell in love with this blow-up spray booth, the “Carcoon.”  It was developed for onsite auto body repair, but it works just as well for woodworking finishes.  Check out this video from YouTube and tell me if I’m not crazy to want one.

 

That left me with one option, build one myself!  So, taking some ideas from other products and homemade booths I saw while doing research, I cobbled together my own plan for a spray booth.  The booth’s frame is made out of 3/4″ electrical conduit.  I found a company online called Yuma’s Bargain Warehouse that sells all kinds of gadgets for building tent structures using piping.  I was most interested in their connectors, and they offer pretty much every type you’d ever need.  The walls of the booth are made of a thick vinyl clear tarp material that is used in the marine industry, and it all connects together with hook and loop velcro.  Since I was putting so much effort into the structure, I also decided to go with real spray booth filters for it as well.  The high-tech exhaust is by way of two box fans – Fancy!.  The last item that is necessary is a whole lot of industrial strength duct tape to seal the seams and floor.  You can check out what mine looks like in the photo gallery below.

Success or Failure?

Overall, I can say that the booth works, but it definitely has some issues.  First off I have to issue a DISCLAIMER:  Don’t spray flammable finishes using this type of setup.  Cheap box fans are NOT explosion proof, and could ignite or blow up.  This would, once again, be worse than the debris vortex outside the shop.  Despite my best efforts, I still can’t get the booth fully sealed up.  This was expected, as the velcro that holds the booth together is not completely airtight.  You can get it fairly well sealed though, especially if you tape over all the velcro joints.  For my needs, it’s good enough, and I haven’t noticed any contamination issues when the booth is “sealed.”

If I were to start over from scratch, I would definitely go with sew-on velcro instead of the adhesive backed velcro I used.  The stick-on stuff just can’t hold up to being put together and taken apart multiple times.  The weight of the heavy duty vinyl panels is even too much, and I ended up having to glue them together at the seams on the top.  The vinyl panels are all one piece that basically look like a ‘plus’ sign, and the vertical corner edges got the velcro treatment.  I could glue the whole thing together, but that glue-up would be a nightmare, and since the booth will sit in front of the roll-up door, and we bring cars in and out, the thing had to break down fairly easily.

Another solution to this problem is to use airtight zippers.  I looked into them once, and they are pretty pricey, but they are available.  If I had zip-up seams, setup and breakdown would take about 15 seconds since I just open up the front and back, flip up the panels to the top of the booth, and we drive cars right through it.  The velcro, even if it were sewn on, takes a while to line up and get on.  Taking it apart is pretty easy though.  I also fit the sides to the frame pretty close, so there is a bit of a tug-o-war going on when I put it together.  That’s an easy fix, luckily.

The weakest link in this design is the entire front end wall.  This is where the intake air filters and entrance are located.  The entrance was made by cutting the front panel down the center and attaching yet more velcro to each side.  I did this to preserve the stick of the velcro on the sides,   This entire setup is terrible, and it is the primary cause of air leaks.  First off, the stick-on velcro doesn’t stick well when you going in and out all the time.  It is constantly peeling off the vinyl.  The other major problem is getting the intake filters sealed.  I haven’t come up with a brilliant idea on how to mount them so that no air can bypass the filter.  It needs a baffle or something, and I am just not that handy.  Instead, I just tape them up, which doesn’t really work well.

One other matter is the air flow of the box fans.  I don’t believe that two box fans provide enough air flow to clear the overspray.  It’s not terrible, but it’s also not optimal.  This could be an effect of having so many leaks, and sealing the booth better could help this problem out.  Also, I decided to mount the intake filters high and the exhaust low.  My hypothesis was this would create an airflow that would go directly across where I was spraying; however, I think that the exhaust holes are too low and the table that I spray on is solid, blocking the air flow.   A better solution would have been to put the exhaust ports up a little higher, at or near the height of the table.  I am considering just adding two more holes and two more fans above the originals to see if my airflow increases and clears the overspray better.  This could be too much airflow, but it’s worth a try and sealing up the old holes would be easy.

All in all, my booth works for now.  It’s not a completely dust free zone for sure, but it’s a significant improvement compared to the dust tornado outside.  You can get it pretty well sealed up as long as you apply enough duct tape over any air leak prone areas.  Getting in and out of the booth is probably my main complaint about it so far.  I cut a slit in the front panel and applied velcro to it.  This works marginally well if you are just bringing in small items, but I would have to totally take the front panel apart to wheel in a full size project.  Plus, this is one of the main culprits for leaks since I can’t really tape the joint – or I would have to tape it every time I entered and exited the booth.

In the future, I plan to upgrade the current configuration to knock out some of the problems one by one.  If I see good results with the upgrades, I will provide an update.  For now, I don’t feel comfortable giving out step by step instructions on how to build one, but you can check out the following links to the pipe connectors and vinyl tarps below:

Yuma’s Bargain Warehouse

MyTarp.com (I purchased the 20 mil thick tarps, and they are definitely tough enough for this application)

Overall, I have to give my DIY booth a 3-star rating out of 5.  It definitely solves some major problems for me, but it just lacks the refinement needed to get excellent results.  I successfully lowered the amount of dust and debris to contend with, it allows me to spray in the winter, and I can get lighting where I need it.  On a side note, I should also mention that I use one more important item with my booth, a wireless remote to turn on/off the fans and HVLP turbine.  I leave the turbine unit outside of the booth and the fan controls are also located outside.  Before I set up the wireless remote, I would constantly forget to turn everything on before entering and sealing the front door behind me.  With the wireless setup, now I just have to remember to bring the gun, goggles and mask with me.

One last Public Service Announcement about spray finishing and cobbling together your own booth:  First off, always wear the proper safety equipment.  This would include, but isn’t limited to, a respirator with the organic filters so you aren’t breathing in the finish vapors and mist.  Eye protection is a must.  It is probably a good idea to cover up your entire body since the finish and chemicals can enter your body through the skin.  Gloves too.  Another consideration that you must think about is if there are any flames such as pilot lights that your finish could get into an combust.  Diligence is the key to staying safe and obeying the rules.  Lastly, there may be city/county/other ordinances such as building codes that could restrict the use of something like this.  You may even have home owners association regulations affecting you.  Check out the rules before you put yours together.

Do you have a DIY spray booth, or would you like one?  Leave me a comment below and tell me about it.  Let me know what you think of mine too by leaving a comment below.  Also, don’t forget to sign up for the NV Woodwerks “Superfan” email newsletter where you can get even more information and updates from NV Woodwerks.

Thanks for stopping by, check back often for new information.

Happy Woodworking!

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