Endurovar - Problems spraying

[Prashun Patel]

I have been unable to diagnose this.

I am spraying Endurovar Flat with my Fuji Semi-Pro 2-stage HVLP.

It is not spraying easily. The air is flowing. The tip is not clogged. My air is 100% open, and the fluid dial is about 80% open.
The first time I tried, it took about 30 seconds to begin flowing. But the material flow was very low. It strengthened as I kept spraying. The flow gradually increased until I was satisfied with the delivery.

I let the gun sit for 2 hours between coats. The second application took about 1 minute for the gun to 'warm up' to reasonable flow. On the 3rd coat, it would not flow - even after 2 minutes of depressing the trigger.

I am using the default 1.3mm air cap. General Finishes recommends a 1-1.3mm air cap.
I have sprayed gallons of Enduro Clear Poly with no issue. Between coats, I often have to pick the scab off the nozzle, but it flows fine after that.
I am not using the basket strainer. I found with Clear Poly it restricts the uptake too much.
When the Endurovar flowed during the 1st 2 coats, it laid down very well; there was no spitting or sputtering. The coat was even and as expected.
I emptied the gun and sprayed soapy water through the system (as I have always done for the Clear Poly) and it immediately sprayed strong and full.

I don't think the issue is clogging or a bad seal on the cup; the vigorous flow from the clean water shows this not to be the case.

I don't think the issue is too small an air cap because of the GF recommendation and my positive experience with Clear Poly.

The only thing I can think is that maybe the FLAT sheen finish is more viscous. I've not sprayed FLAT Clear Poly before (only SemiGloss and Satin).

If I get no other rec's, I'll probably try thinning with water. I hate doing that.

Any help appreciated.

[Tom M King]

I don't know anything about that coating, but typically for the lower sheen ratings, different amounts of silica is added in a lot of coatings to reduce shine.

[Michael Roberts]

"Thin it 'til it flows, and then thin it some more" -- my favorite piece of finishing advise from an Uncle who's laid down miles of finish.

[Jim Becker]

"Thin it 'til it flows, and then thin it some more" -- my favorite piece of finishing advise from an Uncle who's laid down miles of finish.

Unfortunately, that doesn't apply to water borne finishes. They only permit very limited thinning due to their nature. Water is just the carrier and excessive thinning can cause significant issues with the actual finish that's left behind after the water evaporates.
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OP, hopefully John T will comment...he's our resident GF expert relative to spraying that particular finish. But something really does sound amiss.

[John TenEyck]

I'm here, and I was all set to suggest that the check valve between your cup and gun, assuming it has one like my friend's 3 stage Fuji does, was the problem. But then you said it sprays soapy water just fine, so that's not likely the problem. How many psi does your Fuji have to the cup? If it's 5 psi or more then a 1.3 mm N/N should work without problems. I use a 1.0 with my Qualspray pressure assisted HVLP conversion gun to spray both EnduroVar and Enduro Clear Poly. I run 5 psi to the cup. I haven't sprayed the flat version of EnduroVar but I've sprayed a lot of flat Clear Poly and never had a problem or noticed any difference to the other sheens. On the other hand, I use a PPS cup system on my gun and that has a large, integral filter in the outlet of the cup which would catch any agglomerates.

Are you filtering the finish before dumping it into the cup? Have you measured the viscosity and compared it to Clear Poly? I think they should be within 10 seconds and around 45 seconds with a #4 Ford cup.

Re-reading your post where you said it took 30 seconds for finish to begin flowing out of the gun makes me suspicious about something with your gun. If the finish viscosity checks out and you are pre-filtering it, then I can't think of anything else. The cup seal could be the culprit, or the check valve if it has one.

Have I mentioned today how much I like the 3M PPS cup system? I got my friend with the Fuji gun to convert and he said he's never going back. The PPS cup seals better, you can replace the inner cup and lid with every job at low cost (or clean and reuse them until they finally fail after a couple of years), you can see what's in the cup, and you don't need that prone to failure check valve anymore that the Fuji has. Any you can spray upside down or any other angle you choose without starving the gun for finish.

I hope some of this helps, Prashun.

John

[Prashun Patel]

Thanks Guys!

I thought it might be the cup seal too. But I reseated it on the third coat to no avail. Yet, when I switched to water, it sprayed just fine. This might also suggest that the check valve works ok.

The only thing I did not do is strain the material before adding it to the cup; I have always done this in the past with Clear Poly. However, there were no visible particles and it was a brand new can.

I will double check the viscosity, and strain the material.

The head scratcher is that once it started flowing, it flowed great - not sputtery.

I know this will make no sense, but it almost felt like a vapor locked pump. Once it got started, all was fine - And the trigger worked fine then; it was like it wasn't primed. I know. No sense.

John, is the 3m cup pps system Part # 16580? I like that for convenience. My turbine puts out 5.0 PSI according to the manual.

[Tom M King]

The 16580 is the 3M spray gun that's made for the PPS system. I think John was suggesting to adapt your gun to use the PPS system, which is the cup system with collapsible bag in the cup that holds the material, and a strainer in the cap of the cup. They make adapters to use the PPS cup system on about any gravity feed gun.

I have that 16580 gun, and it's reached for more than the others, but unless you want to go to another gun altogether, I'd just get the PPS cup system for your gun. I can't remember the last time I used anything else, since I have all the guns possible set up for PPS.

I think the 3M PPS is on the second generation, but I invested heavy enough into the first generation, that I'm set, and good with that, for a good while.

Anxious to hear the solution to your problem.

[John TenEyck]

I reread your first post, Prashun, and think maybe the finish is drying or gelling in the nozzle between coats. Have you ruled that out?

I just went and checked the viscosity I measured for EnduroVar and Clear Poly. Oops, not what I said earlier. I measured 45 seconds on EnduroVar but only 24 for Clear Poly through a #4 Ford cup. GF's website lists 350 - 450 cps (around 80 - 120 seconds) for Clear Poly and 200 - 300 cps (58 - 74 seconds) for EnduroVar. Either GF is wrong, or I am, or we're using different methods. Still, I can't rationalize how GF measures a lower viscosity for EnduroVar while I measure it as higher compared to Clear Poly. I looked at my gun settings for both products. I use a 1.0 mm N/N set for both, 29 psi inlet air pressure, 5 psi to the PPS cup, all the same. The only difference is I set the needle 1.5 turns open for EnduroVar but only 1.25 turns for Clear Poly, which is directionally consistent with the viscosities I measured.

Prashun, for your Fuji gun, if it has a pressure hose to the stock cup you need the H/O style cup. There are two of them, 16124 is the large size, around 850 ml and 16121 is the mini cup, around 180 ml. Then you need lids and liners to go with the cup you choose. I use lids with the larger, 200 micron filters. You will need an adapter, too, to connect the PPS cups to your gun. I think 3M has a list of which adapter to use for various guns. When you connect the PPS cup to your gun just use a hose, no check valve, at least that's how it's set up for my friend's Fuji.

John

[Rob Young]

Thanks Guys!

I thought it might be the cup seal too. But I reseated it on the third coat to no avail. Yet, when I switched to water, it sprayed just fine. This might also suggest that the check valve works ok.



The check valve may have a partial failure. It is able to pressurize the cup sufficiently to push something "light" like soapy water but not until it has had time to climb up the hill for the more viscous finish (per John's measurements).

Do the maintenance and change all the seals and the check valve as well as run a bit of piano wire through the orifices to make sure something hasn't splashed up and caused a partial clog of the cup air-line fittings.

[Prashun Patel]

Really great input guys. Thank you ALL.

I inspected my cup today and see that there is some build up around the rim where the seal is. I cleaned it as well as the air cap and nozzle - which appeared clean. I will also inspect the check valve.

There is something else I forgot to mention: I was spraying at around 60 degrees F in my garage and it was raining outside, so the humidity was high. Also, the Endurovar can had been in my garage over night. The last time I sprayed Clear Poly - probably 6 weeks ago - it was also similarly cool in the garage, and I did feel that while the flow was never anemic, it was slightly more vigorous at the end of the session than at the beginning. Perhaps that's my culprit...

Will try again tonight. Temps should be about 68. Also, I have kept the bottle of EV inside @ 72 deg all day this time.

I am definitely considering the PPS system, but want to do some more research before pulling the trigger ;)

[John TenEyck]

GF's viscosity values are at 72F or thereabouts. The viscosity will be higher at lower temps., so that wasn't helping you. 60°F is about the minimum for many WB products; you are pushing the envelope.

Just buy the PPS system for your Fuji. No more fooling with cup seals and check valves that always seem to be the weak link of those systems. My friend called Jeff Jewitt and got everything he needed without having to sort it out himself. You can thank me later.

John

[Robert Maloney]

I agree with John. Just get the PPS and don't look back. I was having problems with the cup seal on my Fuji gravity cup and bought the PPS. I have both the large and small H/O cups. They are great. Easy clean up, reusable if you want, and you can spray with the gun in any position. I had a similar problem with Endurovar and found that a bit of finish was gelling in the tip. I now wrap my tip with a wet rag between coats and have not had a problem since.

[Prashun Patel]

Ok, cleaning the cup seal and warming the ev to room temperature seemed to help. The material still took a few seconds to begin flowing, but it flowed fine after that.

I must say that I am extremely impressed with how this product laid down and leveled.

I thought I would find the flat sheen too dull, but in fact it's a very low satin. The first coat on the top side is so nice, I am reluctant to spray a second and mess it up.

This top is a redwood burl, sanded to 1000 and then sprayed with Sealcoat prior to the EV.

Bad lighting on my pix.

[Jim Becker]

Wow...that looks incredible. The sheen is perfect...it looks silky and rich.