Spraying Enduro clear poly

[John TenEyck]

If you are in NYS then either something is really wrong with your gun or the finish is bad. You should be getting around 45 seconds for Clear Poly. I just checked GF's website and they say it is 350 - 450 centistokes which is 100 seconds #4 Ford cup, plus/minus. No clue where they get that from. But if the finish is laying on blue when you lay down too heavy a coat I doubt there is anything wrong with it. But check your new can; it's highly unlikely you got two bad cans. Actually, I've never had a bad can of finish from GF. Of course, a frozen can is something else - but that would be pretty obvious.

Now I'm wondering about the viscosity cup you have. Are you sure it's not a Zahn #4? That would make a lot more sense to use a 1.3 mm N/N for something that measures 24 seconds with it.

John

[Patrick Chase]

Now I'm wondering about the viscosity cup you have. Are you sure it's not a Zahn #4? That would make a lot more sense to use a 1.3 mm N/N for something that measures 24 seconds with it.

Fuji ships their systems with #4 Ford cups. Water measures at 8-9 seconds with the one that came with my Q5, so it's definitely not a Zahn #4 or even Zahn #2.

[John TenEyck]

Oh, boy. Time for an apology. I just went down to check my gun settings chart and found nothing listed in the viscosity column for Clear Poly. So pulled a can off the shelf and measured it. 24 seconds! My apologies for the erroneous info. as regards it's viscosity. (This makes the viscosity listed for Clear Poly on GF's website even more bizarre, but that's neither here nor there for our purposes.)

So, yes, the OP has a Ford #4 cup and is getting the correct number for Clear Poly. That means the product is most likely not the problem; it's something with his gun or technique.

I don't understand why Fuji would say to use a 1.3 mm N/N set unless the cup has very low pressure going to it. I thought Fuji guns have the cup at the same pressure as the air. That's the way it with my friends Fuji rig. For the MiniMite 5 the brochure says it's 6.5 - 9.5 psi. I spray Clear Poly at 5 psi to the cup with a 1.0 mm N/N set in my conversion gun. Something doesn't add up. But I'm sure I could spray it with a 1.3 mm N/N, too. I would just have to turn the fluid flow down a little and it wouldn't atomize quite as well, but I'm pretty sure I could still get good results.

That leaves me wondering about how the OP has the gun set up, which you talked about earlier Patrick. The gun needs to produce a uniform rectangular or elliptical spray pattern. Then when you overlap by half you will get a consistent film thickness. Turning the work 90 deg between passes shouldn't give a checkerboard pattern; it should be two layers of consistent thickness.

Here's a pretty good overview article on patterns and troubleshooting. http://www.spraytec.net/pdf/General%...un%20Setup.pdf

John

[Andrew Goraj]

Oh man. So. I solved the problem. I really debated coming back on here and saying it was something unique, or complicated. I really want to do that. But alas, I'm a man who admits when he is wrong, No matter how embarrassing it may be. The problem...Drum roll please....Was a loose hose connection where the hose connects to the turbine. It was connected at the factory. I've sprayed for over a year and it was tight. Must have just loosened up before I started spraying this new enduro poly. I never thought to check it until I read all of these comments. So all of you were right! Poor atomization. Equipment problem. Yada yada. I just sprayed my table with enduro clear poly, and it sprayed beautifully unthinned using a 1.3 NN on a Fuji mini mite 5 stage ...with a tightened hose connection !

Thank you all for the comments and your time. Regardless of the reason, I learned a ton along the way I didn't know! Both about spraying, and my ego!

[John TenEyck]

We've all been down a similar path, Andrew. The simplest answer is often the right one. Glad you found it.

John

[Patrick Chase]

I don't understand why Fuji would say to use a 1.3 mm N/N set unless the cup has very low pressure going to it. I thought Fuji guns have the cup at the same pressure as the air. That's the way it with my friends Fuji rig. For the MiniMite 5 the brochure says it's 6.5 - 9.5 psi.

MM5 is 9.5 psi. The 6.5-9.5 spec is for the entire MiniMite series. Click on the tabs in the box in near the middle of this page to see per-model specs. One of the big differences between the MM5 and Q5 is that the Q5 has variable speed control and can be run at lower pressures without a cheater valve (which causes flow-dependent pressure drops and requires more iteration to dial in).

I spray Clear Poly at 5 psi to the cup with a 1.0 mm N/N set in my conversion gun. Something doesn't add up. But I'm sure I could spray it with a 1.3 mm N/N, too. I would just have to turn the fluid flow down a little and it wouldn't atomize quite as well, but I'm pretty sure I could still get good results.

This comes back to something you and I have discussed a couple times: Fuji gives very conservative viscosity guidelines in their manual. It's also worth noting that they give a single set of viscosity-to-N/N guidelines for all turbine models (MM 3/4/5 and Q 3/4/5), so they probably assume ~6 psi.

It's also possible that Fuji's guidelines are optimized for speed. The MM5 should be able to feed and atomize finish of that viscosity at a high rate (wide fan, high density within the fan) with a 1.3 mm nozzle. It's pretty impressive in that regard in my experience. Pressure feed does allow you to run smaller N/N when necessary to optimize atomization, but you don't have to in my experience.

[Marty R Schlosser]

I just jumped into this thread and thought I'd throw in my two-bits for whatever it's worth.

First of all, I'm glad that Andrew was able to get things working better, and congrats to all of you who chimed in.

Okay, enough of the platitudes so let's get down to business:

- Selecting aircap sizes is dictated primalily on the finish viscosity. The 1.3 should work out quite well for the measured Ford 4's 25 seconds range.
- Adjusting your gun's settings is paramount to achieving proper atomization. Here's how I do it for panels (which is what you're mostly doing in this job):
1. Fan width: Set to max.
2. Set your turbine's motor speed dial to the 3/4 range. This will give you approximately 8psi (full open = just under 10 on your system), which will result in less overspray and bounce-back, yet still provide plenty of air to effectively atomize your finish.
3. Ensure the air valve on the gun end of your hose is fully opened. In fact, given that you've a 5-stage unit, I'd remove it and never bother putting it back. Your motor speed control will provide you all the air volume control you'll ever need, so you don't need it with your system.
4. Gently close the fluid knob on your gun until it bottoms out. Don't torque it down tightly as that may damage the needle and nozzle. This is now your reference point for fluid. Open it - 1/2 turn at a time - until it's 2 full turns open.
5. Set a piece of cardboard onto your spray stand, and with your gun held the same distance from the target area as you'll be using for the real panels (approximately 8" from the surface) and 90 degrees in both planes, slowly pull the trigger and hold for about 2 seconds then release. Look carefully at the results. You should have a nice wet section in the middle of the fan and finely atomized droplets proceeding outward from there. The wetted area should appear to have about the same amount of wetness to it. If you see droplets instead of fine, mist-like spray then it's not atomizing adequately. Close down the fluid needle by 1/8 turns and do another test on another part of the cardboard. Continue increasing the fluid by 1/8 turns until you have proper atomization. If you're closing down to about the 1 1/2 turn point and still aren't achieving proper atomization, increase the turbine motor speed slightly (try a 10% increase). There must be a proper balance between the air volume and the fluid volume to achieve proper atomization, but only try to play around with one of the variables at a time; that's why I recommended you set the turbine motor speed at a reasonable starting point and play around with the fluid volume.
6. Place a test panel (you did make a few spares, didn't you?) that you'd prepared in exactly the same way as the real panels (i.e. sanded down to the same level, dye applied, etc.). Get out your wet mil gauge. Spray one coat in exactly the same way you plan on doing the real panels, then measure the thickness of the coat you've just sprayed. For most finishes, you should be aiming for 3 mils, but check the manufacturer's specs on the particular finish you're spraying, as it can vary from product to product and manufacturer to manufacturer. If it's too thick, it means you have to move your gun more quickly; too thin and you need to slow down your gun movement across the surface.
7. As regards how the wet coat should look, there should be no "stripes" as you described, but a relatively even amount of finish everwhere. If you have good lighting, you should be able to discern how well your coverage is coming along as you spray. Some finishers always spray one light coat going in one direction, then turn the panel 90 degrees and do a second coat in that direction. This technique is called "cross hatching" and helps eliminate striping. Myself, I do one coat, only in the same direction without rotating the panel, and rely on my technique of proper overlapping of each pass I make, because I have excellent lighting in my booth and can see as I go along that there is correct overlapping going on.
8. Allow that coat to dry to the touch, then see how things look. Of course it'll not be adequate, so you'll have to lay down one or two more coats to have a better idea of how well things are coming along.

I hope this additonal info helps.

[Andrew Goraj]

Very useful! Thanks a lot. I'll try this process word for word tonight. I sprayed some tests last night and it went well. I was just thinking last night, after I finished, how I should go with the max fan that General Finishes has recommended. Since these are 8 foot tables. So I will give that a try as well.