As part of gearing up for my heretofore largest PnP effort, building Karim's redesign of Magic Realm, I first built a spray booth, which wasn't difficult and has proved supremely useful...I would no longer want to spray without it. It helps keep dust and insects off the freshly sprayed items, and reduces the environmental impact and the annoyance of neighbors by filtering out the goop and reducing the odor. It even allows me to spray on rainy days without poisoning the family too much and with only minimal annoyance of the wife if I open a door and place the booth in the doorway with the ventilator blowing the exhaust outside.
There are numerous online how-to's on building spray booths of various sizes out of various materials, but there's nothing to it, really. The general idea for a table-top version like mine is to get a large cardboard box, seal all the holes and cracks with duct tape, attach a fan of some sort to it (blowing air out of the box) and place a filter in front of the air intake.
In the USA, cheaply available furnace filters are usually used. I live in Germany where these don't seem to be available, and used class G4 particle filter mats which are expressly recommended for this purpose and are cheaply available on ebay (~6€/square meter).
The fan was the most expensive part, costing about 30€. Some of the online howto's recommend blowers, which seem to be both more expensive than fans and harder to attach well (intaking air over a larger surface inside the booth.) Of course if you're going to use the spray booth inside, you'll probably want to vent the exhaust with a hose to the outside, and blowers are better for this, usually having a round exhaust for hose connection. I searched the ebay industrial pages and got 1020 cubic meter/hour (~600cfm) ventilator for commercial kitchens. This amount of volume seems to be just sufficient, I wouldn't go for less.
To mount the fan, I ended up just leaving it in the box it was packaged in, securing the fan to the box using screws and very large washers so the cardboard doesn't tear. I cut a large round hole in the back side of the fan box using a circular cutter and placed two pieces of chicken wire, laid at a 45° angle over each other and cut to size, between the fan blades and the outside hole, bending the chicking wire to bulge out slightly to keep it away from the fan blades. On the other side of the box I cut a maximally large square hole, which I covered with two layers of the G4 particle filter matting and attached with duct tape, sealing the edges.
I used a regular cutter and a steel ruler to cut a square hole in the back of the booth box making it as tight a fit as possible, and inserted the mounted fan so it's box is halfway into the hole and sealed all the cracks with duct tape.
You need to see what you're spraying. A lot of tutorials mount a flourescent light in the booth. I cut a flap in the top, strengthening the hinge with duct tape, and taped a jumbo sized zip-loc bag that a jacket of mine had been packed in as a window on the inside of the box. This lets in plenty of light, especially if using outside as I usually do. You can close the flap to protect the window when not in use.
You'll probably want some sort of console to place the pieces on for spraying. Some people use toiletpaper rolls bound together which creates a nice flat elevated surface, but the angle for spraying is poor inside the small booth. I used a large piece of cardboard to create a console with a triangular cross section to angle the pieces slightly. This also seems to allow you to spray until the can is really empty, since you can hold it almost vertically, when spraying. You don't want the console angled too much, however, or your lacquer, etc., will run down the sheet, ruining your piece. I have one large (dinA3) piece of paper with the lower long edge bent up glued to the console to prevent sheets for sliding down.
One thing to watch out for is getting whatever you last sprayed on the back of your next piece, especially if you're spraying spray glue (my second main use of this booth.) since you're spraying the backside with the front side down, and your good front side will get glued to the console, ugh! To avoid this I get a big stack of scratch paper and place two sheets on the console covering the entire spraying area fresh after each spray job. The residue from the previous job will usually suffice to stick the sheets to the console. When I'm done I remove the whole built-up layer and dispose.
The other thing to watch out for is when attempting to spray multiple sheets simultaneously. The pressure from the spray when spraying over one sheet will blow the neigboring sheet around possibly landing on the sheet being sprayed...disaster. I solved this by cutting off the sticky strips of PostIts and using a glue stick to glue these sticky side up to the console where the corners of whatever I'm spraying are. This is sufficient to hold the items down while spraying, but, as designed, they just peel off, leaving the item undamaged.
For protecting from dust while drying I first let the items dry for ~5 minutes in the booth and then transfer to a big flat box next to the spray booth (as seen in the third image from the top) that I first keep outside (to help reduce the stink problem inside) and can later be transferred, box and all, inside for overnight drying without too much stink.
When spraying more than four sheets I separate multiple layers of 4 sheets each with large sheets of cardboard cut to fit inside the box with the ends folded down to prop them up and allow space between the layers. By the time the first sheets of the next layer are ready to be transferred, the previous sheets have usually dried enough (>10 minutes) to no longer be (too) tacky, so sticking to the cardboard sheets by incidental contact isn't usually a problem.
- Last edited Wed Sep 28, 2016 10:31 pm (Total Number of Edits: 14)
- Posted Sat Sep 24, 2016 7:16 am