Spraying beginner - advice

[Phil Potter]

All,

I am a long time lurker, avid forum reader with modest woodworking experience (mostly furniture made from 3/4” red oak), who would like to get into spraying my finishes. 90% of my work has been covered with GFHP WB satin using bristle and foam brushes. I really like the way this material give a really durable finish and allows the quality of the wood to show through.

However, I am getting tired of ‘painting’ and would like to spray the GFHP. I have no experience other than using rattle cans, but wondered if you fine folks could point me in the right direction regarding equipment, options, must dos and do nots. For all intents and purposes, I plan to stick with the WB finishes.

I do have a small pancake compressor, but no more than 2.6cfm, so likely not usable as a source. Also I’d rather not spend hundreds of dollars, especially if I find out I am really poor at spraying!!

Thanks

Phil

[Jim Becker]

You'll find that spraying water borne finishes (and shellac) is relatively easy to get used to. The one piece of advise I extend beyond choosing what equipment to use is that you should be prepared to practice a little. Yes, you'll use a little finish that costs a little bit of money, but it will pay for itself in the end.

Since you have a compressor that's inadequate for spraying finishes and want to do things pretty economical, a lot of folks have spoken highly about the Earlex HVLP systems. Something like that might be a good place to start and if you start to stretch things further, you can then make an investment in a higher end system if you choose. I personally don't have experience with one of these because I do have a large compressor and use a modestly priced HVLP conversion gun with great results. I would expect you could do the same with something like the Earlex with the particular product you mention.

[Stan Calow]

I am a hobbyist, and am happy with my Earlex sprayer. Easy to clean. Yes to practice. I did learn that you have to plan to use a lot more finish than you expect because of the wasted overspray.

[Justin Ludwig]

What is your location? Try searching Craiglist for used compressors, they are everywhere. " air compressor site:dallas.craigslist.org " replace "dallas" with the nearest craigslist city to your location


Your pancake compressor will work, just not for long periods of spraying. 3/8 air hose and hi-flo air fittings will be best. HVLP spraying is all about air VOLUME, not air pressure. Put an airfilter (even those cheap orange disposable ones work) on the line.

Find a HVLP gun at your budget and get a 1.8mm and 2.2mm tip. Spray. Adjust pattern and flow. Spray again. Thin material. Spray again. Make adjustments. Not working? Change tips. Spray, adjust, spray, adjust, did I mention spraying?

It's a frustrating but learning process. Don't get in a hurry. The best thing you could do is buy a local "paint and body" guy a case of beer and ask him for a few hours. ;) Good Luck!

[John TenEyck]

While I personally use a HVLP conversion gun with a 60 gal compressor, I agree with others that your easiest path to success is with a packaged unit like the Earlex. They are reasonably priced, will spray most any WB finish, and the components have been chosen to work together which eliminates a lot of the frustration involved in setting up a compressor based system if you've never done it before.

GF's HP Poly sprays like a dream and I'm sure the Earlex, or similar, will give you great results.

John

[greg bulman]

I just recently bought an earlex 5500. The folks at local Woodcraft’s say it works great with general finishes. I’m still in the learning process myself.

[Phil Potter]

Thanks for the very helpful responses. I saw the guys at GF using the Earlex system and was pretty impressed. One follow up question. My red oak drinks the HP on the first coat and raises the brain quite considerably. Should I spray several very light coats before sanding back, or put on a thick initial spray coat similar to using a brush?

Thanks again

Phil

[Justin Ludwig]

Get a spray bottle and fill with water. Spritz the surface and denib with 320 sandpaper. Fog coat your first coat. Sand. Lay down a good 2nd coat (3 wet mil). Spray a 3rd coat if desired.

[Phil Potter]

Lud,

Excuse me for being dim, but what exactly do you mean by a ‘fog coat’, and how is that achieved with a sprayer?

thanks ,

Phil

[Tom M King]

Practice on cardboard, if you don't have scraps of plywood laying around that are not good for anything else. Don't bother with practicing on horizontal surfaces. Once you get vertical mastered, everything else is easy.

The biggest mistake I see most new to spraying make is to fan the gun in an arc. Instead of fanning your wrist, it becomes part of a robot arm that keeps the spray fan perpendicular to the surface, and a constant distance. This is the same regardless of what type of sprayer you use, from conventional, to airless, and everything in between.

Learn to set the fluid output by holding the sprayer stationary, and spraying finish in one spot. Try different length trigger holds at new spots. This will give you a feel for how the fan covers. Do the same at different distances from the surface. Hopefully, the fan will be only lighter at the edges, but some guns have a thin spot somewhere in the fan coverage. You need to know your gun, for any finish you're going to spray with it, and how to set the fluid, and air controls for doing the best job. With a fan only lighter on the outer edges, your covering passes should cover about half of the last pass. Don't start or stop the spray on top of the piece.

Don't just put finish in your unit, and go to spraying the final piece. Even when I'm starting something that I've done many times before, my first pass is, almost always, on a piece of cardboard.

[Mike Gottlieb]

I agree with Tom. I just started spraying and had a devil of a time getting vertical surfaces right - sags and runs. The folks on this forum gave lots of good advice. Like most have said, it takes lot of practice and adjustments. Don't give up. Practice, practice, practice!

[Justin Ludwig]

Lud,

Excuse me for being dim, but what exactly do you mean by a ‘fog coat’, and how is that achieved with a sprayer?

thanks ,

Phil

"Fog coat" is just misting the surface. Since you're using WB finishes, skip the step of misting with a spray bottle as it's a wasted step and the fog coat will do two things - raise the grain AND lay a bit of solids in the surface. To fog coat a surface the only thing that changes is the speed of your arm moving across the surface. The finish will look like orange peel instead of a wet film.

I can tell you this from experience. Using a cheap HVLP gun and a pancake compressor will be frustrating at first. Your toughest job will be learning the finish's proper thinning percentage for the tip you use. I wish there were a magic number or explanation, but there isn't. Spraying is explained in science terms and but accomplished by man hours. I haven't used a viscosity cup in 20 years and that was because the Navy made me.

I'll give as much simple advice as I can it's all based on hard knocks and TONS of reading- and I'd put anyone of my doors up against a pro painter for finish quality any day of the week:

Put a regulator at the base of the gun.
You should not exceed 15-25psi with the trigger pulled. I only spray super low viscosity stains through my Devilbiss FLG4 and I set it 4-6PSI with the trigger pulled. I think it reads 20-30 when not pulled.
Filter your air.
Filter your material.
Use a 3/8 air hose and hi-flow air fitting. VOLUME, not pressure atomizes and lays the best coat. HVLP stands for something.
Thin your material 20% before you spray anything. Trust me. Just thin it 20% - I don't care what a label says. Thoroughly mix and filter again when you pour into the cup. You can adjust your thinning from there.

Gravity cup: load the material and before you hook up to air, adjust the tip to "wide open" - angle your tip 45* down and pull the trigger full: material should flow out, not run out, not ooze out, but flow - this you'll learn. You adjust the flow rate after you hook up air and spray a bit and test your patterns. But this method lets you know if the viscosity is good. I don't use the method anymore because of experience, but it sure helped in the beginning to understand.

Practice with water and dye. Kool-Aid works. It will teach you how to properly do a 50% cross over pattern. If you can get an even color on cardboard with dyed water, you can coat any finish properly.
FYI - Water will always run out of the tip, even with a 0.8mm if the needle is set to wide open - it's water.


Tom's advice is spot on. If you can spray a second coat on a vertical surface and not get a sag (or orange peel), you're golden. And always spray a test shot every time you reload the cup.

Watch this video: https://www.youtube.com/watch?v=uTSPSiJuxZI

[John TenEyck]

Thanks for the very helpful responses. I saw the guys at GF using the Earlex system and was pretty impressed. One follow up question. My red oak drinks the HP on the first coat and raises the brain quite considerably. Should I spray several very light coats before sanding back, or put on a thick initial spray coat similar to using a brush?

Thanks again

Phil

To prevent grain raising I almost always start with a light coat of Sealcoat shellac. It sprays very, very easily and will prevent the WB finish that follows from raising the grain. It also imparts a warm tone to the wood that most WB finishes lack. Sealcoat is safe under almost all finishes. I've used it many times under HP Poly.

With regards to learning to spray I advocate to start simple and tackle more difficult tasks as you gain experience and confidence. I spray as much as possible horizontally, simply because it's easier, and I recommend you start that way too. It's a lot easier to focus on getting a uniform coat when you don't have to worry about runs and sags. I also recommend you get a #4 Ford viscosity cup. Adjusting viscosity "until it looks right" means nothing to someone just starting out. I've been spraying for about 10 years and I still measure the viscosity of every can of finish coming into my shop, and when I need to thin them to a specific viscosity. Keep good records for each finish with respect to the viscosity, how much you thinned it, and your gun set up. That will simplify setting up to spray that finish each time you use it.

John

[Tom M King]

I agree with spraying on a horizontal surface every chance you get. But you won't learn much control from practicing that though, since it's so forgiving. When I spray doors for a house interior, I have a bunch of rotisseries just for the purpose. I made them years ago, before I had the feel for spraying that I do now, but still use them when it's not too much trouble. Paint, and coatings have gotten a lot more forgiving these days for spraying too, which makes it all easier.

Also, the better your equipment, the easier it all is.

[Phil Potter]

All,

Thanks for the very helpful suggestions. I haven’t decided what to buy yet but I’m going to watch lots of you tube videos and read as much as I can before I take the plunge. I am definitely leaning towards the Earlex system since it should work out the box and allow me to generate some sort of technique (good or bad!).

Thanks again,

Phil

[John TenEyck]

Take the leap. After you start spraying you'll wonder why you waited so long to start.

One thing that we didn't discuss is a spray booth. You need one unless you plan to spray outside, which has it's own set of issues. It doesn't need to be anything elaborate as long as you only spray WB finishes. But you do need one. We can discuss further, as you choose.

John

[David Kenagy]

Thanks for bringing up the booth.

I just got the Earlex 5500, and have a former laundry room next to the shop where I thought I'd make a booth with plastic walls (made from vapor barrier, supported with the poles that grip the floor and ceiling joists). I can close the shop door to reduce dust, but that room is never dust-free.

I might be able to move a Jet air filter that doesn't get much use. But I read of folks who use a filter on a box fan. If I make a frame to hold a filter over a 20x20 box fan, are there specs for the filter to use? (I don't plan to spray much solvent-based finish). Does it make sense to funnel the output to the 4" duct that used to handle the dryer output?

Do I need another filter to cover an air intake? Same specs?

[John TenEyck]

You need exhaust and a 4" dryer vent ain't going to do it. If you want to use a box fan you need an opening as large as the fan, unobstructed. I use the fan from my DC, and I can exhaust over 1000 cfm through a 6" duct out a nearby window.

FWIW, filters on the exhaust side just blind over. If you put the box fan 6 ft or more behind your spray gun WB finishes will be dry by the time the overspray hits the fan and won't stick (but they will plug up a filter). Even if it does, box fans are cheap and if you need to replace it every few years it's less than $20. If you are spraying in a sealed room you can filter the make up air. My temporary booth isn't sealed so I can't filter the make up air, but it doesn't seem to matter. I don't have problems with airborne dust getting on my freshly sprayed parts.

John

[Robert Engel]

Phil,

I started out with a cheap HF purple HVLP gravity gun. Actually doesn't work bad at all. I also use a pressure pot type gun with a 2.2 tip which really puts out the material. Use it exclusively for primers.

I wanted to try something different, so I purchased the Earlex Spray Port (6003). I think if you're looking at buying a compressor this is comparable in price.

+1 on the shellac sealcoat ;-) You can spray that, too. Another thing to consider is grain filling.

+1 on the spray booth. The last couple projects I sprayed in the shop - not the best way to do it.

Respirator with gas filters (especially with oil based) and a good exhaust fan are a must. I don't think a box fan is adequate.

[David Kenagy]

...a 4" dryer vent (won't) do it. (For) a box fan you need an opening as large as the fan. I...exhaust...1000 cfm through a 6" duct...

... filters on the exhaust side just blind over.

John

That helps. My old dust collector only pulled 330 cfm, and its output goes to a big flannel bag. The shop now has a 2hp Oneida cyclone, which showed me how much I don't know about volume, pressure and flow.

I plan on a booth of 4x8x6 (192 cu ft). 1000 cfm means >5 air exchanges per minute (which might be much more than I need?) I can change a 4" hole in my wall to a 6" hole pretty easily, but I'd like to see the math, to know whether I'll be frustrated later.

Loading up the filter ("blinding over"?) would be ok, if I can get through a project on one or two filters. My bigger questions are how to set up enough flow, and how to funnel from one or more fans to a single round duct.

[John TenEyck]

That helps. My old dust collector only pulled 330 cfm, and its output goes to a big flannel bag. The shop now has a 2hp Oneida cyclone, which showed me how much I don't know about volume, pressure and flow.

I plan on a booth of 4x8x6 (192 cu ft). 1000 cfm means >5 air exchanges per minute (which might be much more than I need?) I can change a 4" hole in my wall to a 6" hole pretty easily, but I'd like to see the math, to know whether I'll be frustrated later.

Loading up the filter ("blinding over"?) would be ok, if I can get through a project on one or two filters. My bigger questions are how to set up enough flow, and how to funnel from one or more fans to a single round duct.

You won't get much flow if you try to force the output of a box fan down into a 6" hole. With box fans flow drops off very quickly as static pressure increases, and adding more fans won't improve it. You need an unrestricted outlet in order to use a box fan. If you can't provide an opening equal to the size of the fan then you should forget about a box fan. If all you can provide is a 6" hole then you need a blower. A dust collector fan is a blower. Get a cheap HF DC, tear it apart and just use the fan.

Commercial spray booths were typically based on a face velocity of 100 fpm. The design parameter is different now, nor do you need that much for waterborne products, but the point is you need flow. If your booth has a frontal area of 4 x 8' that's 32 sq. ft, which means a commercial booth that size would have a fan capable of moving 3200 CFM. I get by with about 1000 CFM on a frontal area of about 42 ft, again spraying only WB and shellac, so that's a face velocity of 24 fpm. As long as I spray towards the exhaust inlet no overspray escapes the booth.

If you want to avoid quickly blinding over a filter you need a lot of filters to spread out the load. Look at commercial spray booths. They might have a single exhaust fan maybe 2 ft square, but they will have a wall of filters in front of the fan. To me it makes no sense to use filters in front of a box fan (or DC blower). There's no benefit, only downside.


John

[David Huston]

I had the earlex 5500 to start out with and it worked great. I started out spraying GF white poly and then some Target coatings, pigmented and clear. I found a good deal on a FUJI Mini mite 3 on ebay and upgraded. Dont think I can tell the difference in the final finish from the Earlex. The more powerful Fuji just is a little faster at putting out the finish. The Fuji is also a non-bleed gun versus a bleeder for the Earlex. The Fuji is a little more adjustable but I think starting out with the Earlex is a great idea. Think I sold mine for almost what I paid for it too!

[Phil Potter]

Guys,

Thanks for the the very helpful suggestions. The cold weather has limited my woodworking abilities over the last month or so, but will definitely be checking around for spraying options in the spring. I suspect most of it is just practice and see what works best for me.

Thanks again,

Phil