A Paint Booth for Acrylic Paints

A Nice Place to Paint Freight Cars

I have written before about my switch to acrylic paints, specifically Vallejo paints for airbrushing. To keep down the mess in the house, I wanted a cheap, lightweight spray booth with lots of light and an exhaust system for the particles and slight odor. I have been airbrushing inside with a cardboard box and a respirator to catch particles before the entered my body. It had its limitations.

The Old Cardboard Box Solution.

I started with the idea of using a plastic storage crate about the size of my cardboard box. The plastic was hard to work with as it was brittle and my search for an inline exhaust fan didn’t work out. I was hoping the clear plastic could help with lighting inside the booth, be lightweight, and portable for future moves.

The Original Paint Booth in a Storage Crate Idea.

I live on top of a large granite and marble deposit, one of the revenue sources for the NCR that run through this area starting back in the 1830s. These deposits off gas low level radiation, so my house is fitted with a radon removal system. It is basically a hole in the basement slab with an extraction fan outside of the house to pull the radiation up and away from the house. When I first moved in seven years ago, the exhaust fan on the side of the house wasn’t working, so I found the same fan model and replaced it. Just last month the fan started to vibrate, maybe a bearing was wearing, and it caused a reverberation throughout the house. A new fan was sourced for about $150 and the replacement (a new model number with slight design changes) ended the house-wide vibrations. Then I realized I had a fan that could pull 160+ cfm that works, but with a slight vibration. Paint booth dreams were again alive. And one big advantage is this fan is that it is meant to connect with 4″ PVC pipe and easily adapted to use flexible, metal 4″ dryer hose connections.

The main lesson that I can share from this experience is that lightweight construction is possible on a budget. A little time woodworking with a table saw can provide a strong frame and the walls can be thin and lightweight. Like the walls on the inside of a house, the framing provides the structure and the skin can be weak. Having enjoyed the size of my cardboard box, I used it for a start and created the main structural members from 3/4″x 2″ poplar. You can use another wood, but I was lucky to have access to some hardwood stocks that a friend was willing to share. I created two 18″x !8″ frames for the sides and used half-lap joints with glue, then a light spray to polyurethane to seal the wood. A glued half-lap joint is very strong and provides the main structure for the booth. The width between the two sides was determined by the width of a roll of easel paper. I saw this online, someone used a roll of drawing paper hung at the top, back of their paint booth to allow for a renewable white background for painting and possibly photography. The rolls are available through Amazon and much cheaper at many craft stores for $6, they are used for children’s art easels.

Gluing Half-Lap Joints on Side frames.
A Light Coat of Polyurethane on the Side Frames.

For the bottom of the box I used a thin piece of plywood lying around in the garage. It was 1/4″ pine, which helped with keeping the box light. I added a second piece of 1/4″ under the front lip for dimensional stability. My second choice was a piece of 1/2″ birch plywood left over from layout framing. The width was 20″ to allow for the paper roll to fit within the side frames. The depth was set at 22 1/2″ to give me a little lip on the front of the box for paint bottles, cleaning supplies, and the spray-out pot I use to clear my airbrush. The side frames were screwed from the bottom of the plywood base. I skipped glue here in case I want to take it apart or adjust the size. The added a lip also gave a place for the paper roll to be slid under and secured.

The Paper Slides Under the Lip.

I wanted the top to be clear or translucent to allow light to enter the box and possibly add lighting from outside the box. I was leaning toward buying some plexiglas to cover the 20″x 18″ top of the box. I didn’t need a solid piece of plywood like the bottom foundation, so I was thinking of just using some 20″ wide scrap strip to the keep the sides from moving too much with the plastic to fill the space. Once again a scrap piece of material came to mind. I had several 12″x 12″ pieces of glass from former wall decorations that I had saved to use for my modeling bench as replaceable smooth work surfaces. A couple of pieces of the poplar hardwood I received had reliefs cut into them so two 18″ pieces became the top braces, along with another scrap piece for the back edge. I was going to screw the glass in place as the pieces had holes in the corners, but I decided to use two more pieces of the same trim to capture them in place within a frame, a few thin screws helped hold this together and make it removable should the glass become to covered in overspray.

Top Frame and Light Opening.

For lighting I am using a simple metal, portable flood light sitting on top of the glass and two short screws into the cross braces to keep it from moving and stay above the glass. The light fixture is fitted with a 5000k LED floodlight bulb which operates cool to the touch and is the same bulb used over my layout. Do not try this with an incandescent bulb, they are way too hot and a possible fire hazard being in contact with cardboard and finished wood! The 5000k bulb should help with having the paint applied in the booth look the same as it would on the layout.

LED Light Fixture in Place.

A simple dowel was used to hang the roll snugly between the sides. I mounted it as high and as far back in the box as possible. The roll I bought is 75′ long so I need to remember to buy the same size in a few years as I have seen much longer rolls with larger diameters available. The cardboard used for the back wall is visible.

Adding white cardboard or foam-core is just the covering for the back and the sides, it provides no structure, but keeps the negative pressure pulling air from the front of the booth (where is protects the user) and white allows for better light reflection inside the box and thus more light on the paint subject. It is just stapled in place so that it is easy to replace. We’ll see how this works over time.

The radon fan needed a mount as in its primary use it is attached to braced 4″ PVC pipe with rubber collars on the outside of the house. (insert photo of fan outside house). Here again I took advantage of scrap lumber, this time a 24″x 24″ piece of birch 1/2″ plywood left over from my layout’s modular structure construction. I built a shelf 10″x 10″ to be as wide as the fan and used a jigsaw to cut a 5″ hole in the center to allow the fan body to sit down into the shelf. To mount the shelf to the cinder block wall of my basement I cut a mounting bracket with a dado cut to fit the shelf and then added some angles from the shelf down to the bottom of the mounting bracket. I gave this a light spray of polyurethane to give it some dimensionally stability over time. After attaching the mounting bracket to the wall with three Tapcon concrete screws, I added a couple of drops of acrylic adhesive caulk to attach the fan housing to the bracket and keep it from moving around, while providing a soft mount to keep vibrations to a minimum. I only used a couple of drops of adhesive as I want to be able to cut the fan free should it fail in service.

The Assembled Parts of the Radon Fan Shelf and Mounting Bracket.

Venting the booth outside house is always a challenge. A window can be a great option. I didn’t have this option in the unfinished side of my basement. Then I caught a lucky break that not one in a million modelers gets, I found an unused dryer vent to the outside just seven feet from my intended booth location. It still goes outside and was plugged with expanding foam to keep out small animals. I can’t figure out why it is there, the washer-dryer is fifteen away and there are no nearby plumbing connections to suggest the washer-dryer had been moved at any point. I can’t help you if you are not that fortunate, but I can say the radon fan will push some air as it is sized to move a lot of air two stories up, so a longer run on the exhaust side of the fan is practical. Keep in mind this is only for use with non-flammable solvent paints and finishes, don’t try this with flammable solvent based paints!!! If it doesn’t clean up with water, I don’t use it.

A Fortunate Dryer Vent.

This is a design-build project, so I had a general sketch or two in place and set out to build it to meet the design intent with the materials on hand, adjusting as needed. And I am writing this blog as I am building it, so one of the last details to complete was how to connect the duct work to the side of the box. In the original plastic storage crate design I was going to use a 14″x 14″ filter in front of the fan connection at the back. I realized a side mount fan would be better for my new box design and allow the booth to sit closer to the wall and more out of the way. I knew this wasn’t a good a design to get the best laminar flow across the face of the paint booth, but with 160 cfm pulling through the fan, I was going to exchange all of the air in the box about once every two seconds. Adequate air flow shouldn’t be a problem. The plan was to put a 4″ coupling for flex duct on the top edge, near the back of the side nearest the fan and use some type of filter to protect the fan from paint particles. So far I have only invested time, as all the materials were on hand. I grabbed the 14″x 14″ inch furnace filter to see how I could attach it to a side frame or maybe consider something else. Serendipity struck again and the filter fits perfectly into the popular side frame opening. It was a press fit! I would like to say that was planned, but it was per luck. With the fan pulling through one corner of the filter, I actually think I can get four times the filter life as I will rotate it periodically to put a fresh corner of the filter closest to the fan intake. So next I attached a coupling connection to a 5″x 5″ piece of the 1/4″ plywood with a 4″ hole and…

Furnace Filter Press Fits into Right Side Frame

The finished box, now a paint booth, needed to be attached to the wall and/or held up on legs. I wanted the booth at layout height so I was painting models at the height they would be viewed. I decided to use some plastic shelves from Lowes that are 18″ wide. I attached them to the wall with 1-1/2″ conduit clips to keep it in place. It was a little top heavy. The $20 shelves gave me a place for paint and thinners. A nice bonus.

I connected the flex dryer hose to the connector and hit a few gaps with duct tape for some and caulk for permanent connections. I may add a piece of plexiglas across top front to increase air movement through the box. It pull the fumes away, but you can never have too much ventilation.

Duct Connection, Cardboard Sides, and Conduit Straps Holding it All in Place.

This was a fun project and added a little professional touch to my modeling. It doesn’t hurt to have nice tools and this one was low cost. Model on ya’ll.

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Developing My Painting and Decaling Techniques for HO Scale Freight Cars

The final results of my techniques for adding paint, decals, and a flat finish to a scrap-box boxcar.

With “Stay at Home” public health orders in place across the United States, it seems many are finding extra time and a renewed need for their hobbies. I am no exception and the time in the evening to escape work tasks gives me a needed change of pace and time away from my kitchen table, now work station. Completing a few projects has been fun, though one painting misstep with Acrylic Floor Finish added some frustration and gave me a reason to consider practicing my techniques and possibly narrowing them down to one basic process and deciding which products I like to work with the most.

For me, the first and most important step in developing preferred painting and decaling techniques was to consider a new airbrush. I had been using a single action Badger Model 200 with siphon feed for years. I did not enjoy it, I could not seem to get fine paint control (also a function of using various paint brands and types) and it took so much paint to fill the jar up to siphon hose, clean up took as long as actual painting time. On and off I subscribe to TrainMasters TV, an online model train video series, and one of the first segments I watched was on airbrushing by a representative of Iwata airbrushes. I loved the fact that by using Vallejo paints and a gravity fed double action tool, the expert on the screen was bale to quickly and precisely paint models and cleanup the brush. Those were the things I wasn’t able to do with my current Badger setup. This is not a knock on Badger, it was the whole system that got me where I wanted to go and I am sure other brands could do that also. I believe the key was the double action for control (takes a little practice), easy cleanup and consistent paint, and the use techniques shown in the video.

With my son home, part of the layout has been diverted to a Clone Wars battleground. Hoping the Death Star doesn’t wipe out this entire planet.

I ended up purchasing an Iwata Eclipse Hp-Cs Value Set with Hose, then quickly purchased a Iwata-Medea Universal Spray Out Pot and large container of Iwata-Medea Airbrush Cleaner for easy clean up. Watching the video will show the techniques for using all of these much better than I can explain here.

The consistent paint turned out to be the Vallejo Model Air series, they are thinned for airbrushing and available in a wide variety of colors, though not mainly labeled for railroad colors. This is a big drawback, but I decided to tackle it by starting with the Vallejo Steam Engine Weathering Set I found on Amazon and then add colors available on Amazon and eBay as they were not found local to me. Their line of Model Color paints are also a good and only have to be thinned to the consistency of the Model Air paints to produce the same results. I use Vallejo airbrush thinner for this. An excellent source for additional information about spraying acrylics and color matching with Vallejo paints is available at this link, The Model Railroad Hobbyist’s Guide to Acrylic Painting… in a post-Floquil World. This was written and published by the folks at Model Railroad Hobbyist with the support of Testors.

I have also started my own system for color matching after ordering several Vallejo brown colors that could be used on steam era freight cars. I took a piece of scrap styrene and drew lines on it to allow space for a paint sample along with manufacturer and stock number information. I had done something similar years ago with a few PollyScale and Floquil paints that I could use for comparison with the new colors. The one thing I would do different if starting over is to have a larger paint sample space, maybe a square inch, and use an airbrush to paint the sample. A few other modelers are using Vallejo paints and in online forums, I have heard that Model Air Rust 71.080 is a good match for early Santa Fe Brown and Model Air German Red Brown 71.271 is a good match for early PRR FCC.

This article started when I was looking a “better” flat finish. I have used Testors DullCote for probably 40 years and have almost always had great results. The few times the results were less than stellar are probably user error. A recent online forum post led me to try Winsor & Newton Galeria Matt Varnish, which I found on Amazon. Sorry I can’t find the original post in order to give credit to the person who shared the information. The 8.4 fluid ounce container was around $12.00 which makes it considerably cheaper than DullCote.

The first trial was on a boxcar from the scrap box that had a very shiny finish. The black door in the photo below show the reflection from a light several feet away. Using my Iwata airbrush I put a little bit in the paint cup without thinning. It was fairly thick but sprayed easily at 25psi and dried fairly quickly. You could see it dry as the gloss disappeared and the best part of the product is water cleanup. I sprayed warm water through the brush into the spray out pot several times and then final washed it, as I always do, with Iwata-Medea Airbrush Cleaner. I did so quickly as I wasn’t sure what could be left behind. Subsequent uses of the airbrush haven’t revealed any residue causing problems.

After it was dry for at least 24 hours, I wanted to see how weathering techniques might work on this finish. In the third picture you can see I applied some Tamiya Dark Gray pinwash (they call it Accent Line Accent Color) to the grabs, ladder, and lower sill and pan pastels to various places on the far end. I wasn’t trying to achieve any particular effect just determine compatibility. The application and results did not differ from what I am used to with DullCote finished models, I see that as a plus. This will be my future dull finish product.

Original high gloss finish as found in scrap box.
Very dull finish after one coat of Galeria Matt Varnish (same lighting as photo above)
I waited 24 hours and added some weathering to test compatibility.

As I stated at the beginning of this blog, I haven’t thoroughly tested my techniques from start to finish, so I decided to give it a go with another shiny boxcar from the scrap box. I left the original finish intact and sprayed half the car with the primer I have been using recently, Tamiya Oxide Red Fine Surface Primer and the other half with a product I have been wanting to try, Vallejo USN Light Ghost Grey Surface Primer. The grey was not thinned and cleaned up with my standard procedure of Iwata-Medea Airbrush Cleaner and the spray out pot. The coverage was better, cleanup almost as easy as the spray can, and the cost significantly less, so I think most future projects will use the Vallejo product. For brass painting, I will probably still use the Tamiya product line for what I feel is better adhesion to the metal.

The original finish.
A light coat of each primer was applied to each side. The right side showed a little bleed through of the original white BN logo.

The next step was adding a coat of Vallejo Model Air Rust 71.080, a good freight car brown color. I roughly masked off the ends to keep a little primer showing and gave the model a thin coating sprayed at 25 psi. The results of both ends seem about the same.

Coverage and color of over both primers appears to the be about the same.

After 48 hours of dry time, the next step will be a coat of “Future” acrylic floor finish to add a glossy, smooth surface for decaling. With so many great reviews online about this product, I really want to master its use. I have used it successfully with a brush on small projects like replacing a reweigh date or adding chalk marks, but I have not done so well on larger surfaces or with an airbrush. I got the best finish on the car pictured when I dropped the air pressure to 20 psi and kept the brush back about six inches. Again, a rough masking job shows the progression of steps from the original green. As an aside, I was painting some blank decal stock green to use on B&O caboose window sashes and found that Vallejo Game Air Sick Green 72.729 is a close match to the BN Green on the original model. The second photo below shows a patch I sprayed with the Sick Green.

Acrylic Floor Finish applied to the center section.
The Sick Green patch is to the right of the door, lower half of the car.

Time for some decals. Part of what started this search for a better process was the use of some very old decals on the recently gloss sprayed caboose I was working on. They disintegrated when I put them on the model, even before adding setting solution. This gave me a chance to learn about Microscale Liquid Decal Film. I used some decals from the same sheet for this project and gave them two coats of decal film. One coat didn’t seem to be enough to hold the decals together. I placed them over rivets and ribs to make it a bigger challenge. My go to has always been Walthers Solvaset so that what I went with. I ordered some Microscale Microset to try for this experiment but it didn’t arrive in time. My Solvaset technique is the lay the decal into a puddle of the distilled water I used to soak the decal and then wick up the water with the edge of a paper towel. Then I immediately apply Solvaset lightly around the edges the decal and let it wick under the decal. If there is too much and it begins to puddle I wick it off the model. I never touch the decal when the Solvaset is wet and I usually keep the model lying flat. I repeat several times over the course of a few hours and watch everything blend into the rivets and seams to know when to say when.

These decals all came from sheets that disintegrated in water and these were treated wtih Liquid Decal Film. I could probably get the film to disappear with some more setting solution but I wanted to see how the matt varnish covered.
I trimmed the decals to allow plenty of clear film to test my techniques and only put on three applications of Solvaset. The decals snuggled nicely on the seams and rivets.

And a final coat of Matt Varnish to seal the deal. Again, I sprayed at 25psi, straight from the container, and covered the surface with just enough to get a solid gloss shine before it dries. It flashes off very quickly and cleans up with water.

The Galeria Matt Varnish covered the decal film well and allowed it to blend very well. I am happy with the results. I left a thin strip of the gloss finish for comparison.
I am impressed with the ability of both clear finishes to lay down a thin coat and allow the rivets to show through the decal. The B on the right was placed on a row of rivets to test this and I think it passed.

This adventure started when I wanted to test a new matt spray finish and it has sold me on that product. Dullcote was becoming expensive and sometimes unreliable because of the spray can nozzles. Now I am more comfortable with the acrylic floor finish and feel like I have a total finishing system that is repeatable and easy to airbrush. Time to finish the caboose I was working on. Stay safe!

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