Had some issues spraying

[Jeff Monson]

Curious if anyone has ideas on what happened to some areas I was finishing last weekend. What was supposed to be a couple hours spraying doors and face frames turned into a weekend long ordeal. Poplar face frames, mdf inserts. I primed with HSF5000 primer, 2.0 tip in my 3m accuspray 20lbs of spray pressure. I ran over them with 220 before spraying with a hand block and wiped off the dust with blue scott towels. So I started spraying EM6500 with a 1.8 tip, same gun same settings, I did thin maybe 5% with water. I hung the panels from hangers in my booth and sprayed them vertically, as you can see from the photos there are areas where it just didnt seem to adhere, seems the finish kinda "slid" off. I dont get it, these panels were not exposed to any type of oil, grease, etc. I'm very fussy about handling them. Part of me thinks it has to do with how the gun was atomizing the product?? I ended up sanding the panels smooth and spraying them laying down flat. I did not thin this time and used all the same settings and processes. The EM6500 laid down really nice and flat so I'm very happy with the end result.
463836463837

[John TenEyck]

Just guessing Jeff, but I'd say you were spraying too heavily for the thinned finish to hang on the vertically hung door and it sagged. Laying it down flat was the right move. I try to spray everything flat if at all possible as it is so much more forgiving.

I'm surprised you could use the same gun settings for the finish thinned or straight out of the can. You are about on the limit for EM6500 White with a 2.0 mm N/N. TC says the viscosity is 28 - 30 seconds Zahns #4 cup. That's about 100 - 110 seconds #4 Ford cup, which is what I use, and that's pretty viscous for a gravity feed gun with a 2.0 mm N/N, even though TC says you can use a 1.8 - 2.0 mm N/N set. 20 psi air pressure seems way too low, too. I'd think you would need more like 30 psi to have a chance at good atomization. Did you spray some burst patterns to see what the pattern was before spraying?

When I spray something I've never used before I start by measuring the viscosity regardless of what the manufacturer says it is. If I don't have a gun that can spray it w/o thinning then I thin it to fit the gun and N/N set that requires the least thinning. So after thinning I put it in the gun and shoot some burst patterns on paper or cardboard and adjust the fluid and pressure settings with the fan wide open to get the best pattern I can. If the pattern still is subpar, I thin it more. Once I get the pattern so it's acceptable then I know my chances of laying down a smooth coat of finish is pretty good, at least on horizontal stuff.

I hope this helped some.

John

[Jim Becker]

What John said...I also prefer to spray flat. I do edges first and then the face.

[Jeff Monson]

Just guessing Jeff, but I'd say you were spraying too heavily for the thinned finish to hang on the vertically hung door and it sagged. Laying it down flat was the right move. I try to spray everything flat if at all possible as it is so much more forgiving.

I'm surprised you could use the same gun settings for the finish thinned or straight out of the can. You are about on the limit for EM6500 White with a 2.0 mm N/N. TC says the viscosity is 28 - 30 seconds Zahns #4 cup. That's about 100 - 110 seconds #4 Ford cup, which is what I use, and that's pretty viscous for a gravity feed gun with a 2.0 mm N/N, even though TC says you can use a 1.8 - 2.0 mm N/N set. 20 psi air pressure seems way too low, too. I'd think you would need more like 30 psi to have a chance at good atomization. Did you spray some burst patterns to see what the pattern was before spraying?

When I spray something I've never used before I start by measuring the viscosity regardless of what the manufacturer says it is. If I don't have a gun that can spray it w/o thinning then I thin it to fit the gun and N/N set that requires the least thinning. So after thinning I put it in the gun and shoot some burst patterns on paper or cardboard and adjust the fluid and pressure settings with the fan wide open to get the best pattern I can. If the pattern still is subpar, I thin it more. Once I get the pattern so it's acceptable then I know my chances of laying down a smooth coat of finish is pretty good, at least on horizontal stuff.

I hope this helped some.

John

Thanks for the input. I did do a couple test patterns and was pleasantly surprised how well they came out. I should get really start using a viscous cup but I can usually get a good read on my product after pouring and a few tests. Just seems weird that it did this in a few areas with no rhyme or reason. I sprayed these initially with a horizontal fan and moved up and down on the panels with a steady motion. Lesson learned on trying to save time and spray them hanging.

BTW is water the best choice for thinning the products I'm using?

[Tom M King]

You just got too greedy, trying to cover too much. The more you thin something, the easier it is for it to sag. That's why I like airless for thicker stuff-no thinning needed.

As much experience as I have spraying different things, I still spray on horizontal surfaces every chance I get.

[John TenEyck]

As far as I know water is the thinner of choice for WB products. I sometimes use Extender alone or in addition to water, but only if I need more open time for the finish to flow out. Extender doesn't cut the viscosity as much as water but longer open time can lead to more sagging on vertical surfaces. Horizontal is the way to go if the project lends itself to it.

A plastic Ford #4 viscosity cup costs like $6. I check every new gallon that I use. You'd be surprised how much some products change. Probably not enough that you could tell visually, but the cup don't lie. I keep a cheat sheet with my spray gun kit that lists every finish I've used, what the viscosity typically is, and what my standard gun setup is. I use those settings to set up the gun for my spray burst test and adjust as needed.

John

[Jim Becker]

With waterborne finishes, water is the reducer but extender can also fill all or part of that need as John indicates. However there's a limit to how much you can thin a waterborne product. The reason is that water is the carrier for the finish. When you add too much water, you're spreading out the molecules of the actual finish, so you can start to have coverage issues in addition to sagging/dripping/running, etc. So any time you can optimize the gun to shoot the finish with minimal alteration, that's the better choice. I try to only use a little extender for its inherent benefits and not do any other thinning. That's worked well with the 6008 gun with the PPS system for me.

[John TenEyck]

You can safely add at least 10% water to nearly any waterborne. I've added almost twice that amount a couple of times and not had any problems other than having to spray more coats to get the build I needed. However, I'm with Jim that matching the gun to the finish so you don't need to thin at all is the best option most times. Airless and pressure assisted guns give you a lot more flexibility in meeting that objective with waterbornes which tend to have higher viscosity than comparable solvent based products.

FWIW, the purple HF gun sprays some WB finishes beautifully when thinned 5% or so. At $10 with a coupon it's a true bargain.

Bonus points. You can turn any non-pressure feed gun into a pressure assisted fed one by adding a PPS H/O cup to it with a separate air regulator supplying 0 - 10 psi air to it or by hooking it up to a pressure pot. Tom or someone else above mentioned it in passing but it bears repeating.

John

[Warren Lake]

spray guns that are pressure have lapped needle nozzle.

Some guns will leak if fluid is pressurized amount will depending on the fluid viscosity and pressure.

[Jim Becker]

FWIW, the purple HF gun sprays some WB finishes beautifully when thinned 5% or so. At $10 with a coupon it's a true bargain.


Of course, to add to the fun...they have more than one purple gun now. :D

[Jeff Monson]

That's worked well with the 6008 gun with the PPS system for me.

Jim, which gun are you using and can you elaborate on the PPS system? I'm using the 3m accuspray gun and the disposable cup setup right now and like you stated I hate to start making adjustments past its "comfort level". So can a person retro fit a different gun to the 3m disposable cup setup? Thanks as usual!!

[Warren Lake]

they have adapters to put the 3M system on just about any spray gun. Ive run them on old suction feeds as well. The satas came with large stainless cups I never used just went straight to the 3M stuff.

[Jim Becker]

Jim, which gun are you using and can you elaborate on the PPS system? I'm using the 3m accuspray gun and the disposable cup setup right now and like you stated I hate to start making adjustments past its "comfort level". So can a person retro fit a different gun to the 3m disposable cup setup? Thanks as usual!!

I use the same gun as John...the 6008 HPLV from Homestead Finishing with the PPS cup system. For the benefit of folks ready that are not familiar with PPS, if you remember the Playtex baby bottles that had the collapsable insert, the PPS system uses similar with about 5 psi of pressure behind them. That provides pressure assist for moving fluid out of the cup and makes spraying almost "anything" a pleasure. I generally use the 1.3mm N/N for waterborne finishes, but have actually been successful with the 1.0mm N/N with some products. I've sprayed SW ProClassic which is like mud with no issues. Cleanup is a snap. The cup inserts are disposable, but honestly, I've used a total of three of them over the last two and a half years since I bought the gun. I just wash them out with hot water while cleaning my gun in the same. Were I buying today, I'd opt for the LVLP version which I didn't know about when I was buying.

Yes, you can retrofit many guns to use the PPS system. You just need the correct adapter for the particular gun you want to work with.

[Warren Lake]

Is there a gauge on the gun that tells you 5 PSI or you have an adjustment to match it to the material? Im curious on the number.

[Jeff Monson]

I use the same gun as John...the 6008 HPLV from Homestead Finishing with the PPS cup system.

Ok, I looked at that system on the Homestead site. You and John have me convinced on it. After a little reading it sounds very versatile as I know I have a full kitchen to do in tinted EM6500. If it excels at the higher viscosity then I'm on board.

Question, do you find yourself messing with the pressure to the container? I see 5 to 10 psi is listed, just curious if its another setting to worry about?

[Warren Lake]

you have needle nozzle size, your material diff types behave different, your air pressure fan adjustment and how much the fluid is open, your temp has a big affect and its one the reasons they use viscosity cups to match the speed of material so it sprays the same each time.

Past sprayed material from 3 PSI assist up to 30 PSI plus for some heavier Becker primers. As soon as you go too high you fan will turn into a figure 8 rather than oval or straight whatever your gun type. You can bring it back a bit iwth some adjust ment. Pressure is good its a turbo on a small motor, but you do it wrong and you will add orange peel just your settings.

[John TenEyck]

Jeff, well, of course the pressure setting for the cup is important. That said, I leave it on 5 psi for almost everything. The exceptions are Sealcoat where I use 3 or 4 psi and BM Advance and similar high viscosity products where I use 6 or 7 psi. If the PPS cup lid liner and lid are clean and you get a good seal when you tighten the cap then you can refill and keep spraying with no adjustment required to maintain the cup pressure. If you have a little leakage then you may have to make an adjustment but it's no big deal. The pressure gage is on the inlet to the gun so it's easy to check and adjust. To be clear this pressure regulator is to control the pressure of the cup. You need a separate regulator to control the pressure to the gun. I use two, one at the compressor set to 90 psi, and a second at the 20 ft hose reel to the gun, typically set to 29 psi, but I do set it lower for low viscosity products, as low as 20 psi for dyes and Sealcoat.

You will like the AM-6008 SmartPak with the PPS cup. It sprays darned near anything and is all contained in one nice, easy to store, case. Tell Jeff, Jim and I want our referral fee. (Just kidding. I have no affiliation with Jeff or Homestead Finishing, just a happy customer.) I have no doubt the LPH-400 Iwata is a better gun and if you are looking for a lifetime gun and have a compressor that can supply enough air it would be a great setup. Probably looking at $750 though with 3 needle/nozzle sets and PPS cup.

John

[Jeff Roltgen]

Jeff- I have the 6008 kit as well, and keep it reserved for pigmented finishes, as the pressurized cup does make all the difference in pushing almost any viscosity through it, rendering thinning almost completely unnecessary for those thicker products. And yes, go with the PPS system. Converted everything to this a couple years ago, and it's absolutely revolutionary if you haven't tried it.

John- That LPH-400 LV is a super-low air consumer. (LV=low volume). Probably the least amount of air consumption of any gun I've ever owned, so really no concerns on compressor size. It is well worth adding to anyone's arsenal for it's advanced atomization engineering. I keep that guy reserved strictly for clears. Absolutely wonderful gun.

The pairing of these two has rounded out my main spray application line up, giving me confidence to produce high-quality finishes of almost any type.

Only thing else I occasionally like to use is a Titan 440i for clears and an older Spray-Tech reserved for latex, but this is only due to the fact that they can dispense so much so quickly when I have the finish room fully loaded with large scale projects.
Honestly, once I switched to the PPS system, I rarely run the airless any more, as those two guns just sing and clean-up is such a breeze.