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Finishing Spray Gun

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I'm about to embark on doing some spray finishing, and while I've searched the forum concerning spray equipment, there seems to be some conflicting opinions with regard to the appropriate equipment. I've used rattle-can lacquer and acrylic on a few occasions, sometimes with the piece off the lathe, and sometimes with it spinning on the lathe.

My current compressor is 4.5 gal, has a 1/4" hose on it, and is rated to supply 3 cfm at 90 psi. With that in mind, I'd like to get some feedback and have the following questions:
  1. When I've used the rattle-can, I spray for perhaps 3 seconds in one area and release. I repeat the brief spray application until I have the piece covered. Given that the psi at the gun is reduced to perhaps 25 psi, and the actual spray time is only for a few seconds at a time, will my current compressor be able to do the job?
  2. My plan is to use water bourn finishes (for safety reasons). When researching spray guns, much of the info I've read relates to automotive finishing. For spraying water bourn finishes for wood, what size needle is most appropriate?
  3. As I'll be spraying hollow forms, anywhere from 6" to 15" in height, what size cup would be appropriate?
  4. Is there a known shelf-life for water bourn finishes, and if so, what is it (approximately)?
  5. Should I use a water trap prior to the spray gun?
  6. As this is a new endeavor for me, I don't want to buy a high end gun. Will any of the guns in the $75 - $125 range give a good finish. What gun do you recommend?
Thanks.
 
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I'm not an expert by any means, but have done a little automotive type spraying as well as some kitchen cabinets, with interior paint, and plantation shutters.

You compressor will be adequate. I would put water trap in you line and also a regulator at the base of you spray gun.

I would look for a small touch up/detail HVLP gun. These will hold enough material for 2-3 coats on a small item and will allow you to get closer to small openings.

I started with this
TrackKit1_zpsmoe6yfgc.jpg

and finished line this
DSC_9097a_zps2tjop1hb.jpg
 
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All guns, compressors, and water based are not identical. So there is no accurate answers for all your generalized questions. 25 psi is very low for the inlet of the gun. Even HVLP guns need around 40psi at the gun inlet. For that tiny compressor, you'll want a touch up gun at the biggest. Definitely not a full blown automotive gun. A hollow form will take less than a 1/2 pint, depending on the number of coats. When you run a tiny compressor the air gets really hot and if it's humid, that means you will make a ton of condensation in the tank. You need filters and water separators. Water seperators don't work well if the air remains hot. You will need a desiccant or paper element filter located as far away from the compressor as possible. Just hanging it at the end of a 25' hose will not do you any favors. Also of note is that waterborne materials still have lots of chemicals, it's just that it doesn't stink. You'll still need quality carbon cartridge filters on a mask.
 
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Chris - nice looking bike! Thanks for your input.

Richard - Thanks for the feedback. I agree with you on the need for a mask with carbon filters. Any suggestions for the size of the nozzle/tip?
 

Randy Anderson

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I've not sprayed any of my turning work but do have several spray rigs I use for other projects so, might be helpful info. I only use my compressor driven spray setups for large projects - barns, fences, etc. Hard to manage and keep going well for smaller things. I purchased an HVLP sprayer from Rockler a few years ago for making plantation shutters and love it. No compressor needed. Cheap plastic parts and all but very simple operation, cleanup and works very well on small projects I do.
 
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Solvent based lacquer can be sprayed with a Harbor Freight $15 gun if you add a regulator to bring the compressor pressure down to 30-50 psi or so. (and a filter) Not sure about water based. The solvent based dries fast and spraying in your driveway is one way to reduce toxicity concerns, for you anyway; hopefully the amount of overspray isn't enough to hurt the environment. With the size of pieces most of us turn, your compressor has adequate capacity.
 
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Chris - nice looking bike! Thanks for your input.

Richard - Thanks for the feedback. I agree with you on the need for a mask with carbon filters. Any suggestions for the size of the nozzle/tip?
I'd need to know the viscosity of the clear finish to recommend that. You can buy a Zahn cup to measure that if the manufacturer doesn't have nozzle size recommendations.
 

Roger Wiegand

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Perhaps (well certainly) overkill for finishing small turned objects, but I've been wowed by the Qualspray guns and the service and support provided by Jeff Jewitt at Homestead Finishing. After bad experiences a long time ago I finally relented for a big project I was doing and bought an HVLP gun from Jeff and did a couple projects using water-based finishes from Target Coatings. All I can say is Wow! My past experience was with products from Minwax and the like which I hated (the "Look of Real Plastic"); the clear finishes and pigmented "lacquer" products Target sells go on like a dream and look really good. The 3M PPS system is amazing-- a collapsable plastic cup liner to replace the paint tank. With a pressurized system it lets you spray from any position, even upside down. The liners are supposed to be disposable but I've been reusing them after a quick rinse without difficulty, making it much cheaper.

It's a bit much to set up for finishing a small turning (well, maybe 10 minutes to clean the gun), but I'm interested in trying the finishes on some turnings. I'll need to figure out how to hold the work to access all sides.
 

Roger Wiegand

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I use a lazy Susan.
How do you get to the bottom? I was thinking some sort of mid-air suspension system would be required-- I've seen people hang closed vessels on a bent wire. Not so clear how you might do that with a bowl. I mostly use wipe on finishes (Maloof poly/oil is my favorite) and I can handle the piece to completely cover it and set it on painters points to dry. I'm thinking I don't want to touch the sprayed surface.
 
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Roger - I'm also looking at the Target products. Did you use the EM 6000, or something else?
Do you know what size tip is in your spray gun?
 
Last edited:
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IMG_4945.jpg I have the HF HVLP cup gun, and have had mixed results -- mostly good results. I have a regulator on a short piece of air hose that goes between my long air hose and the gun.

A completely separate/new thing to add to this discussion is a spraying location. I have the 'small' size "Spray Shelter", by Homeright. It's great! It's like a miniature pup tent. It's close to 3x3x3 when fully open. It has some sort of flexible plastic stays inside it to form it. Take it out of its zippered storage bag and it pops open. I set it on a table outside, or my truck tailgate, put a couple pieces of wood in it, one on each side, just to hold it in place if there's a breeze, put my little lazy Susan in there and spray away. When I'm done, it folds up like a bandsaw blade does (the trickiest part of using it), and goes back in the bag with the lazy Susan for the next time. You can find them on sale often. I think I paid about $25 for mine. I highly recommend it as a dust-free spraying location!
 
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Truck tailgate? I don't want my vehicles anywhere close to spraying finish! Where does the overspray go when you spray into a tiny pup tent? I'd assume right back into your face? It would be infinitely better if there was a filter and small fan in the back.
 
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Truck tailgate? I don't want my vehicles anywhere close to spraying finish! Where does the overspray go when you spray into a tiny pup tent? I'd assume right back into your face? It would be infinitely better if there was a filter and small fan in the back.
There's a flap in the back of it. I guess it sort of equalizes the 'pressure' while you're spraying. Not sure. But, I will say, I don't have a drop of anything I've sprayed on my truck. I value my truck! Everything sprayed stays in the 'tent'. Every once in a while, before use, I'll take it outside, hold it more or less upside down, and spray a lot of air in there to clear out anything resembling dust or particles. Then spray away. I've used it a couple dozen times over the last couple years and nothing's gotten out of it or on me. I use the $20 HF HVLP cup gun. I've also used rattle cans in it as well. I just really like the fact that I can spray something without a lot of prep cleaning areas, clearing numerous things out of the way, etc., because there's a lot of dust in my garage shop.
Just my $.02. YMMV
 
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I have sprayed quite a bit of furniture and turnings. I've use Target waterbourne EM2000, M6000, & EM9000. EM6000 for turnings. Also sprayed a lot of nc and precat lacquer. I use an HVLP CAT CPR-G gun rated at 11 CFM @ 29 psi to the gun with the CPR air cap, with the 3M pps system, both qt and 6 oz size cups, the smaller cups are ideal for turnings. Compressor is rated at 5.3 cfm @ 90 psi. It's ~30-40 gal res size. Spraying large furniture I have to wait on the compressor, but with turnings and the short trigger time, there's no issue. I use a cheap inline little plastic housing filter/water trap, never any contamination issues. I normally don't use my "spray room" for turnings (it drops down from the ceiling), I don't really need it. I have a 1000 cfm blower fan with twin 25" x 25" filters for exhaust and I can spray small stuff in front of it without much overspray getting away. I can exhaust the blower outside or into the shop. With WB it dumps into the shop if cold outside.

With waterbourne I use the 1.5 mm needle/tip. While the cheaper guns can spray waterbourne and get it on the wood, I found they need hi pressure, increasing air use and overspray, decreasing efficiency, and resulting in a so-so finish. A gun with a great air cap will finely atomize waterbourne finish, allowing lower gun pressure, less overspray, less air, and a much better finish off the gun. For turnings in particular, finish off the gun may not be as critical, depending on desired completed finish. I sand and polish them out to a fully filled hi gloss.

A touch-up or detail gun will work great for turning, using less air, but IMO you still need to spend some $ if you want spray WB for a great atomizing air cap and multiple needle/tip combinations if you decide to spray other finishes. I also spray heavy paint as well as very thin shellac. Viscosity determines needle/tip requirements. Best to get a gun with SS fluid passages to just not have to worry about rust - you are running water through it. You can do a final flush with DNA and probably be ok with a non SS gun.

Pretty sure Target lists shelf life in the tech documents for their finishes. I think it is 2 years. I have successfully sprayed some 4-5 year old finishes, but I keep them in the house in a closet environmentally controlled.

Only a particulate filter is needed for spraying, not organic vaper. Target lists the rating, I forget. Since I had a respirator rated for solvent finish spraying I was good to go and didn't worry. BTW Jeff Wiess, owner, chemist, formulator, etc will welcomes and will answer phone calls and emails concerning setup and product use.

WB can go on great, no fumes to worry about, easy to sand and polish out, but one big drawback - no chatoyance. I don't understand all the chemistry reasons for it. but it refracts light differently then solvent varnish, shellac, and lacquer and does not give that tiger eye effect. It will look very drab and lifeless compared to solvent lacquer for hi gloss finishes I have had good success using shellac under WB to get chatoyance but it is a pita to have to do when I can spray solvent lacquer and not have to worry about sanding through to the shellac or change what I'm spraying. It can be worth it for furniture where I will use lower sheens and go with the finish off the gun. I don't use it for turnings anymore.
 

Roger Wiegand

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Roger - I'm also looking at the Target products. Did you use the EM 6000, or something else?
Do you know what size tip is in your spray gun?

I bought the "woodworker's package" that came with three tips for my gun. I've been using the 1.3 mm tip for the Target clear finishes. I don't have that much experience and haven't tried others. Some folks report that the 1.0 mm tip works well with that gun, I haven't tried it yet.
 

Roger Wiegand

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WB can go on great, no fumes to worry about, easy to sand and polish out, but one big drawback - no chatoyance. I don't understand all the chemistry reasons for it. but it refracts light differently then solvent varnish, shellac, and lacquer and does not give that tiger eye effect. It will look very drab and lifeless compared to solvent lacquer for hi gloss finishes I have had good success using shellac under WB to get chatoyance but it is a pita to have to do when I can spray solvent lacquer and not have to worry about sanding through to the shellac or change what I'm spraying. It can be worth it for furniture where I will use lower sheens and go with the finish off the gun. I don't use it for turnings anymore.

Interesting-- I reflexively apply a wash coat of shellac to almost everything I make before applying a film finish, so have never noticed this. That would be a huge drawback.
 
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I've used gravity HVLP for over 15-years and still feel clueless. In the above thread I don't think I saw the words abrasives or sandpaper. I get good results but only after sanding the orange-peel. Of course sanding the sealer is for removing orange-peel / flattening and to create a mechanical bond to the next coating, be it more sealer or, if the surface is "perfect", whatever finish coat. The finish coat material, of course, has orange-peel and must be sanded (rubbed out) with progressive grits to the final product. How anyone can spray, let dry and be done is amazing. I'd jump at the chance to work in a chop-shop just to learn how to spray.

Also, the 29-lbs pressure on the HVLP guns is more an industry standard - I clear-coat at 36-lbs which gives much better results.

Regarding Roger's comments on "getting to the bottom", a good approach for larger work is to leave a tenon, attach a 1/2" pipe-flange and a 10" nipple, and do all finishing / sanding / filling - whatever is needed. When done, remove the tenon on a Kelton mandrel, sign your name, and coat with a bit of finish. However, for the final clear-coats, I usually mount on an expander (kinda like an umbrella) and am able to spray the entire piece, bottom included. Makes sense for larger hollow-forms - will be happy to send pics if anyone is interested.
 
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Let me know if you have any questions - not sure if the pics are "self-explanatory". Obviously they are for larger hollow-forms. The pic with the black cherry shows the simple fixture used for 90% of the finishing effort - I use the umbrellas for the final clear-coats.
two umbrella resized.jpg umbrella w blk cherry resized.jpg two umbrella resized.jpg umbrella w blk cherry resized.jpg
 
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Thats a very unique and innovative solution. Im guessing any of the “umbrella” shafts can be captured in the fixture? Kind of an internal expanding mandrel rubber chucky method - the shaft bottoms out in the piece and the flaps expand against the sides, or the top? Small hinges to allow the wood slats to pivot. Interested in the center threaded pieces that the hinges mount to, how are they made?

You’ve hollowed a piece or 2. You have probably mentioned it elsewhere, but what hollowing system is used?
 
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Not sure what you mean with "umbrella shafts can be captured in the fixture" - it's all one fixture - I'm showing an earlier version (top) and a later version. You may be referring to the "finishing horse" - after the turning is "done", I put a 1/2: pipe flange and 10" nipple on the remaining 3" tenon - most of the coatings are then applied - a large black cherry is in the pic on the finishing horse.

After the surface is ready for clear-coat, the piece is put on the lathe on a Kelton mandrel and the tenon replaced with a concave bottom. That's when the umbrella is inserted and secured. The top umbrella in the pic is the best reference. The shaft is a 1/2" threaded rod. The bottom triangular housing has a captured 1/2" nut - I turn the shaft until the umbrella gets as high as possible. The junction nut compresses the top housing which expands the umbrella. I put a pad on the umbrella ends with double side 3M foam tape - I also put a pad/double sided tape on the piece on the thrust bearing. The real challenge in the first unit was finding the small hinges.

I use a Rolle Munro-2 standard "off the shelf" with a long handle - an internal tool rest that utilizes pivot pins is the key - I stand at between 4 and 6 o'clock with both hands on the end of the handle.

If I was reading the above I doubt I'd have a clue what it means. Send me you phone and I'll give you a call.
 
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