Need advice on spray booth filters

[GU-11]

Gave up waiting for fricking Tamiya to bring in the damn spray booth, and got one from a local hobby store at a fraction of the price. It's a Hakko 493 smoke absorber, and is supposed to be used to absorb toxic fumes from soldering.

Thing is, I'm having a hard time finding replacement filters for this, as the hobby store doesn't sell it. I thought of using the filters for Tamiya's spray booths, but if the damn shop doesn't even have the spray booths available, I doubt they'll have the filters.

Can anyone advice on what I can use for as a DIY filter for this thing? Sponges, insulating material, or even scotch brite scouring pads?

The filter that came with the smoke absorber looks and feels like a black sponge or loofah, and feels stiff.

The store owner said the filter can be reused if I spray mainly acrylic paints, which I do. Since acrylic paints are water-soluble, he said I could just wash the paint off and reuse the filter indefinitely.

For lacquer or enamel paints, he suggested I wash it with the appropriate thinner for said paints.

Should I call BS on this, or is this true?

ACTUALLY, do I even need a functioning filter? I'm placing the spray booth in front of an open window, and any exhaust will be directed outdoors. Some of the DIY spray booths don't even have one.

Edited November 13, 2012 by GU-11

[coronadlux]

Saw this while searching for a replacement... If you scroll down you will find the home made filter.

http://www.starshipmodeler.com/tech/pa_booth.htm

Here's a home depot link to the filter and charcoal pads...

http://www.homedepot.com/h_d1/N-5yc1v/R-100600323/h_d2/ProductDisplay?catalogId=10053&langId=-1&keyword=filter&storeId=10051#.UKH-6YaaKSo

http://www.homedepot.com/h_d1/N-5yc1v/R-100600325/h_d2/ProductDisplay?catalogId=10053&langId=-1&keyword=filter&storeId=10051#.UKH-8IaaKSo

Hope that helps and saves you money

[Kylwell]

As one of the inventors of the SMM bucket filter, I can tell you to use cheap furnace filters to catch the particulates & an activated charcoal filter to grab the fumes. ACF can be found for humidifiers, air cleaners, etc @ hardware stores. They're a touch pricey, in the case of the bucket filter the ACF cost more than all the other parts, but they're worth it.

[MechTech]

If your venting directly outside without chance of the airflow coming back in, it won't matter except to keep the fan clean. If the window is just open and the fumes could get blown back in, the carbon will help save your respitory system. Kylwell is right. I usually make a board that fits into the window by my bench and cut a standard 3" dryer hose hole for it to vento out of. Outside there is a flap to keep out critters, ran, and the wind blowing it back in my face. Just an idea. - MT

[GU-11]

Thanks for all the advice, guys!

My budget's a little tight right now, so I might have to forgo the expensive carbon filters until maybe later. I can't find furnace filters here in Malaysia, as it's a tropical country with no use for furnaces. I might be able to find the charcoal filters, though.

For the time being, I'll have to make do with simply pinning or taping the curtains together, with only the rear of the booth exposed to the outside. Would that be sufficient?

One more thing; while waiting for a reply yesterday, I stumbled on a tutorial at ehow.com that suggests using a damp cotton cloth as a filter. Someone even recommended using a a coffee filter as an alternative. They're cheap and easily available, but do they work?

Obviously they won't be any good for filtering out fumes (although the damp cotton cloth technique supposedly does), but can they actually be used to keep the fan clean WITHOUT hampering the fan's suction?

FYI, I use only acrylic paints (Tamiya, and Pylox spray cans), with surface primer being the only lacquer medium.

Edited November 14, 2012 by GU-11

[Kylwell]

Coffee filters are dense enough that getting a draw through them could be tough. Look for AC filters, they might do the trick. Could be a bit pricier but they're usually washable. Cotton or linen cloth will work well @ catching paint particles but could clog up easily. Hence the wet to make them easier to rinse out.

[GU-11]

Thanks for the info, Kylwell. AC filters should be available at hardware stores, if I look for them hard enough.

For the time being until I get those AC filters, I'll try out the cotton cloth trick.

I know it;s a stupid question, but should I use a single layer of cloth or fold it into two layers? I'm asking because I'm not sure if a single layer is enough to prevent the paint from getting to the fan.

[Kylwell]

Really depends on the thread count. I'd keep it gauze-like and go with 2 layers. Part of what you want is to create little bits of turbulence which either throw out the heavier particles or spin them into the cotton. Either way, once stopped by the wet cotton the airflow won't be able to pick them up again.

[GU-11]

Thanks again for the advice, Kylwell.

In this case, some of those really old tee shirts I have should be just thin enough to still be somewhat gaze-like when folded into two layers. I just need to get the cloth slightly damp, right? Worried that getting the cloth too wet might cause water to get sucked into the fan.

[GU-11]

Just a little update here. Built a makeshift window seal for the smoke absorber out of cardboard, and set up a basic spraying station.

Also found some grease filters for cooker hoods at Ace Hardware to use as replacement filters. It's made of some kind of white fibrous material that looks thin enough not to interfere with the fan's suction.

Here's the setup:

One question, though. It's currently the rainy season at my place. While I know I shouldn't spray-paint while it's raining, can I do so once the ground is dry outside? It rains almost everyday, so I don't think I can find the recommended 2 to 3 days of sunshine before spray painting.

Anyways, thanks for all the help everyone.

[MechTech]

It all depends upon humidity. Any clear coats will most definitely be affected by humidity. If your airbrushing water based paints, especially matt finish, then you're probably fine as long as the humidity is low in your house. Gloss coats may also be a problem. If you have a dehumidifyer, heater or air conditioner in your house they will remove the humidity to safe levels.

For those people who live in humid all the time kinda places like Florida, they will paint their stuff and then slap it into a food dehydrator! Our house is usaully dry (summer or winter) so I'll even spray outside and quickly bring it into the closet to sit and cure. My advice, do a test on something like a sheet of plastic and see what happens. I've even had resin get ruined for letting it sit outside in humidity, but yet bringing it inside is fine.

Test it out and see what happens. Something else you might want to try, put a big box around your filter unit to help catch stray spray and concentrate the fumes into the filter. I got some old fans and I'm about to do the same thing at my bench. I hope everything works out well for you! - MT

[Kylwell]

Being in Colorado, high & dry, I have no help about dealing with humidity. If it gets above 30% humidity here it must be raining.

[GU-11]

It all depends upon humidity. Any clear coats will most definitely be affected by humidity. If your airbrushing water based paints, especially matt finish, then you're probably fine as long as the humidity is low in your house. Gloss coats may also be a problem. If you have a dehumidifyer, heater or air conditioner in your house they will remove the humidity to safe levels.

For those people who live in humid all the time kinda places like Florida, they will paint their stuff and then slap it into a food dehydrator! Our house is usaully dry (summer or winter) so I'll even spray outside and quickly bring it into the closet to sit and cure. My advice, do a test on something like a sheet of plastic and see what happens. I've even had resin get ruined for letting it sit outside in humidity, but yet bringing it inside is fine.

Test it out and see what happens. Something else you might want to try, put a big box around your filter unit to help catch stray spray and concentrate the fumes into the filter. I got some old fans and I'm about to do the same thing at my bench. I hope everything works out well for you! - MT

Thanks for the advice, Mechtech!

The air-conditioner in my guest room (using it as my spraying room for now) is busted, so I might have to get a dehumidifier. Problem is, I've never seen one being sold anywhere locally. Ironically, humidifiers are everywhere! Maybe it's to counteract the drying effects of the air-conditioners--FYI, the tropical heat here makes AC's a neccesity rather than a mere luxury.

Food dehydraters might be a good option, although I'm not sure if they even sell these things here. Hell, I might just import one if I have to, as it seems to be a sound investment, given the constant humidity where I'm at.

I usually place my sprayed kits into a plastic container immediately after spraying to prevent dust from getting on them anyways, so if I can get a smooth coat on the kit, keeping them sealed from further humidity shouldn't be a problem.

I'll do as you advised, and test things out on a sheet of plactic before starting on the actual kit.

As for putting a box around the filter. can I use cardboard? I read at a forum that cardboard might get dust onto your sprayed parts or something like that. Hnestly, I've seen numerous modelers use carboard for makeshift spray booths, and I haven't heard any complaints about dust. So, how true is this?

Being in Colorado, high & dry, I have no help about dealing with humidity. If it gets above 30% humidity here it must be raining.

Must be great spray painting where you are. I take it you get pretty smooth and quick-drying coats of paint almost every time.

[Kylwell]

Yup.

Check your local hardware stores for dehumidifiers. They usually carry them, often for basements that have moisture issues.

[MechTech]

Cardboard is fine! I made a large size booth out of one once with no issues. Dirt and overspray will not stick to cardboard anymore than a plastic or metal booth. Both still require an occasional dusting.

At that time my shop was co-located with the laundry room. I was nowhere near a window and lived in an apartment style housing area so just going outside to spray wasn't the easiest. I lived in a windy area too so painting outside hardly ever happened. What I did do is take my drier hose, stick a "Y" on it and also connect my spray booth. The drier never backed into my booth, nor my booth go into the drier (which my wife appreciated)

I just used a nice sturdy box that I refashioned to shape with a box knife and glue gun. Three computer fans sucked the air out. It wasn't enough for spray paint, but it did the trick with glue (no good "safe glues" back then) and my airbrush. I hope that helps! - MT

[GU-11]

@ Kylwell,

I've been searching months ago for dehumidifiers here in preparation for my indoor spray-painting, but nobody seems to sell them. Living in a hot and humid tropical Asian country, most everyone has an air conditioner at home, which is a dehumidifier in itself.

The biggest problem is, the AC in the guest room where I'm setting up my spraying station is busted beyond repair. Not sure if and when I'll be able to replace it with a new one.

Can I use these disposable ones instead? They're all I can find.

Cardboard is fine! I made a large size booth out of one once with no issues. Dirt and overspray will not stick to cardboard anymore than a plastic or metal booth. Both still require an occasional dusting.

At that time my shop was co-located with the laundry room. I was nowhere near a window and lived in an apartment style housing area so just going outside to spray wasn't the easiest. I lived in a windy area too so painting outside hardly ever happened. What I did do is take my drier hose, stick a "Y" on it and also connect my spray booth. The drier never backed into my booth, nor my booth go into the drier (which my wife appreciated)

I just used a nice sturdy box that I refashioned to shape with a box knife and glue gun. Three computer fans sucked the air out. It wasn't enough for spray paint, but it did the trick with glue (no good "safe glues" back then) and my airbrush. I hope that helps! - MT

Thanks for the tips, MT! Sounds like a very cool setup you've got there. BTW, it sounds like you've moved out of the apartment since then. Just out of curiosity, what's your current spraying setup like?

Anyways, cardboard it is, then. Now, to the man-cave!

[EXO]

I need a spray booth so bad. My main enemies right now is the cold and the shorter days. I find this thread so informative.

[Kylwell]

GU-11, I'd never thought about a moisture absorber like that. It could work, I've known of figure painters living in humid climes using desiccants to help things dry faster. Usually they'll put the model & desiccant in a somewhat closed container, i.e. put a box over the 2. The cardboard will also help. You'd be amazed @ how much moisture corrugated cardboard will hold.

The only dehumidifiers I've been able to turn up in Asian countries are commercial units. Probably a bit much for the home.

[GU-11]

@ Kylwell,

Thanks for the tips! I was planning to use a plastic container to keep the parts after spraying, but if cardboard and desiccant actually works better, then I'll use a cardboard box instead.

Yeah, all the places I checked either didn't have dehumidifiers, or only stocked industrial-scale ones. In general, it's harder to find certain stuff here that's common in the US. Heck, I couldn't even find respirators here, which was why I had to resort to buying a spray booth in the first place.

Edited November 21, 2012 by GU-11

[EXO]

I'm also gonna need a down draft table. I wonder if I can combine the 2.

[Kylwell]

Give me a bit and I can p/u a respirator and ship it to you if you'd like. A good one runs $20US.

[GU-11]

Give me a bit and I can p/u a respirator and ship it to you if you'd like. A good one runs $20US.

I seriously appericate the offer, Kylwell, but I'm going to try and see if the spray booth works well enough first.

Besides, getting replacement filters is another hassle, and I'd hate to trouble you every few months.

BTW, another update. I added a DIY cardboard booth as MechTech advised. Next step is to maybe add a lid to keep the dust out when it's not in use.

Is this good enough? FYI, the box isn't taped or glued to the window seal to make it easier to dismantle after a spraying session.

Edited November 22, 2012 by GU-11

[GU-11]

Just tested the smoke absorber this afternoon. Sprayed some chrome spray onto scrap plastic. Used a double layer of cooker hood grease filter.

Honestly, I'm not sure if it's working as well as it should. I tried a few light coats with it, and the smell of the spray still lingers a little. I could actually see the paint particles floating in the air around the cardboard booth. It does clear the air sufficiently enough after a few minutes, which is pretty good considering I'm spraying inside a closed room.

As a safety precaution, though, I'll leave the room between coats and wear a mask while spraying.

I've never used a "proper" spray booth before, so I've no idea if how the smoke absorber matches up to the branded ones.

Is this good enough for a spray booth, or should I use only a single later of filter for better fan efficiency?

[EXO]

Do you have air going into the room? You need air entering for proper circulation.

[GU-11]

I keep the windows closed, but I do have the door open and the ceiling fan turned on. Is that sufficient?

Also, here are the specs for the smoke absorber:

17 Watts

37 cubic feet per minute airflow.

Edited November 24, 2012 by GU-11

[EXO]

that should be good. depends on how strong the fan is and it doesn't disturb the flow of the smoke absorber. It's always better if the air goes directly towards the exhaust.

Now you just have to worry about whether or not the filter is blocking the air from going thru.

[GU-11]

I keep the model kit between the fan and the spray can, meaning I'm spraying at the fan, so most of the overspray is aimed at the fan.

As for the filter, I'm using a double layer of cooking hood filter cut to fit the size of the grill. I tested it with a dollar bill. It doesn't exactly suck the bill onto the grill, but the bill sticks to the grill when I place it there. I think I'll use a single layer of filter also, as the layer under the first one isn't stained by the spray. It should improve the fan's suction.

Edited November 24, 2012 by GU-11

[MechTech]

The booth loks great! It may be that the fan does not have enough suction. It was desinged for soldering which does not put out that much vapor as compared to spraying a compound. Are you spray painting from a can or airbrush? A can will definitely put too much out. The airbrush may be better. If your sticking to water based paints, you're probably good sfaety wise. Oil based will be another story. - MT

[GU-11]

Thanks, Mechtech!

Yeah, I tested the booth with a can of industrial lacquer paint (chrome effect), and the smell was pretty strong.

I checked the specs of the smoke absorber, and as you said, it's pretty weak compared to the branded spray booths that are at least double the CFM and wattage. No wonder the instructions (written by Mr. Hobby) said to aim the spray directly at the fan.

I guess I'll use the booth for airbrushing acrylics, and go outside when using lacquer spray cans.

BTW, would the smaller Tamiya TS spray cans be safe when used at the spray booth? They seem to spray with less pressure than the industrial cans, and the mist is finer.

Also, I heard that Tamiya's TS sprays are actually acrylic lacquers. So are they considered "safe"?

[GU-11]

Minor update:

I noticed some overspray going behind the smoke absorber, and the paint particles settled onto the smoke absorber and surrounding area in dust form. So I added another piece of cardboard cover with a square cut into it to prevent overspray from getting behind the smoke absorber and concentrate the overspray in front of the fan.

And since I spray standing up and aiming at a downward angle (the fan is also tilted upward), hopefully I might be able to replicate at least a little down draft to increase the efficiency of the fan.

Edited November 25, 2012 by GU-11

[MechTech]

^{The main problem is that the spray can (any size can really) will put out too much more than the fan can extract. I made a booth out of three nearly the same size fans and all it could keep up with was the airbrush and glue vapors. External breezes will also keep your fan from extracting the gases too. It's 40 degrerss F on average right now and when I went to get some clothes out of the drier, they were freezing cold (and dry). That reminded me of the blow back from the much stronger enviroment versus yours (mine) tiny fans.}

^{For now, I think you got it right. Spray outside and let it cure inside, preferably a closet if you don't mind not using it for a while . Otherwise, your work looks great.}

^{If you can find a more powerful fan that is brushless, it should be safe to use. It won't have an ignition point and as long as the switch is out of the way, you should be fine. I used three AC brushless fans and never had anything explode or flame up. BUT, error on the side of caution! - MT}

[GU-11]

Again, thanks for the pointers MT.

I never factored in the breeze from outside. The area where I live is ridiculously breezy, so that's probably another thing to consider. Whenever I remove the smoke absorber from the slot in the window seal, I can actually feel the wind blowing in through the slot. I guess that means no spraying or airbrushing on windy days, even indoors.

If I find a suitably strong brushless fan (200 cfm and above) I might make a second booth just for spray cans. Since I have to dismantle the booths after spraying anyways, it won't be any more or less of a hassle to have one or two booths.

Either that, or I decant the paint from the cans, thin them, and then spray them through the AB. Not sure if it's worth the trouble of cleaning the AB afterwards, or the risk of clogging the nozzle.

As for storing the parts for curing, I've got one of those huge plastic containers to place them in (yeah, the ones they use to make DIY spray booths). These should be impervious to humidity and dust, since they're airtight.

BTW, are Tamiya acrylics considered water-based or alcohol based? The Tamiya site calls them "water-soluble paints" yet there's a "flammable" logo on the bottles, and from the smell alone, it's obvious that the pigments are contained in alcohol.

Edited November 26, 2012 by GU-11

[Kylwell]

Tamiya bottle paints are water soluble alcohol based acrylic lacquers... Best if thinned with either of Tamiya's thinners you can thin them with water, alcohol or lacquer thinner. I prefer using their alcohol based thinner and use Mr. Color Leveling Thinner if I need a harder cure.

[GU-11]

Thanks for the info, Kylwell!

Tamiya is the only brand I can easily get a hold of here, so it's good to know it can be thinned with non-branded stuff.

Hopefully I'll be able to try out my AB on the spray booth later today or tomorrow morning, if the weather holds up.

[MechTech]

Glad that helped. One thing you can try is to put a stiff, but light weight flap up on the outside (unless you have a screen there). The flap will allow the exhaust to go out, but any breezes from coming in. Then of course you'll know if a breeze is too strong since nothing will go out - MT