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Thread: Orange peel when spraying GF High Performance Topcoat

  1. #1
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    Orange peel when spraying GF High Performance Topcoat

    I'm trudging along in my first cabinet making journey and am now spraying the interior panels with General Finishes High Performance Topcoat and am hitting some challenges that I could use some feedback on. I'm using an HVLP gun with a 1.3 tip and thinned with water about 5%. The finish is getting a bit of orange peel when I'm spraying but flattens out fairly well when dried. That said, you can still see divots at some angles when in direct sunlight and that bothers me, regardless of whether or not it would be visible in the cabinet interior. I've put on 3 coats now and have sanded each coat with 320 in between and am wondering where I can go from here to solve it as it hasn't gotten better. Could I thin with some General Finishes Extender to give it more open time and hopefully flatten out more? Is sanding it with 1,000 to 2,000 after where I am now a better option to just remove the divots? Any suggestions or feedback welcome, you all have been a tremendous help for me on this project.

  2. #2
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    I would try the extender rather than the water, personally. You also need to be sure you're getting good atomization and not coating too heavily.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  3. #3
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    Quote Originally Posted by Jim Becker View Post
    I would try the extender rather than the water, personally. You also need to be sure you're getting good atomization and not coating too heavily.
    +1 on the not coating too heavily. I've been spraying a fair amount of GF HP lately. They say 3-5 wet mils. I stay toward 3 mils. Definitely looks a bit rough when first sprayed, but levels OK for me. I'm not thinning it at all, and also use a 1.3 tip. If you don't have a wet film gauge, I'd start with that.
    --I had my patience tested. I'm negative--

  4. #4
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    Quote Originally Posted by Paul F Franklin View Post
    +1 on the not coating too heavily. I've been spraying a fair amount of GF HP lately. They say 3-5 wet mils. I stay toward 3 mils. Definitely looks a bit rough when first sprayed, but levels OK for me. I'm not thinning it at all, and also use a 1.3 tip. If you don't have a wet film gauge, I'd start with that.
    I don't have a wet film gauge but can easily grab one this weekend. From where I am now would you recommend just sanding again with 320 and laying down another coat?

  5. #5
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    I get orange peel with my HVLP gun if I shoot from too far away. 8" or so works for me. 12" can get bad.

  6. #6
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    1.3 mm is way too small for HP Poly w/o substantial thinning, if we're talking about a gravity or siphon feed HVLP gun. I used to thin it 6% to get the viscosity down to 45 seconds #4 Ford cup for a 1.8 mm N/N set. For a 1.3 mm N/N you will probably have to add 10% water or 6 - 7% water + 3 - 4% Extender. In any case, you need to get it down to about 20 - 25 seconds for it to spray well. If you don't have a #4 Ford cup you can buy a plastic one for around $6. Get one along with the wet mil gage.

    Orange peel comes from too heavy a coating and not enough time for it to flow out. Adding Extender will increase the open time to help it flow out, but try spraying thinner coats, too. Higher atomization pressure will help, too. If the temp. is really high and the RH really low where you are then you may have to add even more Extender, maybe 5 - 6%, while keeping the viscosity in the same range.

    HP Poly is a nice product, but Enduro Clear Poly looks just as nice, is more durable and has a lower viscosity, at about the same cost. You will still have to thin it a little to use a 1.3 mm N/N, but not nearly as much as the viscosity in the can is 45 seconds, compared to 60 with HP Poly. It is very easy to spray. Or look at Lenmar Duralaq WB. Low viscosity in the can, sprays very easily, looks great and has about the same durability as HP Poly, and is a lot cheaper. I get it at my local Benjamin Moore.

    John

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    Quote Originally Posted by John TenEyck View Post
    1.3 mm is way too small for HP Poly w/o substantial thinning, if we're talking about a gravity or siphon feed HVLP gun. I used to thin it 6% to get the viscosity down to 45 seconds #4 Ford cup for a 1.8 mm N/N set. For a 1.3 mm N/N you will probably have to add 10% water or 6 - 7% water + 3 - 4% Extender. In any case, you need to get it down to about 20 - 25 seconds for it to spray well. If you don't have a #4 Ford cup you can buy a plastic one for around $6. Get one along with the wet mil gage.

    Orange peel comes from too heavy a coating and not enough time for it to flow out. Adding Extender will increase the open time to help it flow out, but try spraying thinner coats, too. Higher atomization pressure will help, too. If the temp. is really high and the RH really low where you are then you may have to add even more Extender, maybe 5 - 6%, while keeping the viscosity in the same range.

    HP Poly is a nice product, but Enduro Clear Poly looks just as nice, is more durable and has a lower viscosity, at about the same cost. You will still have to thin it a little to use a 1.3 mm N/N, but not nearly as much as the viscosity in the can is 45 seconds, compared to 60 with HP Poly. It is very easy to spray. Or look at Lenmar Duralaq WB. Low viscosity in the can, sprays very easily, looks great and has about the same durability as HP Poly, and is a lot cheaper. I get it at my local Benjamin Moore.

    John
    Thank you for the thorough feedback this is super helpful. I've got a gravity feed gun and I actually have a 1.8 tip as well. I went with the 1.3 as that was recommended on the GF website but manufacturer recommendations often don't represent reality.

    I do not have a #4 Ford Cup and will pick one up. Do they carry them in retail stores in general? I see them online but am struggling to find one at the local BORG.

    I'm married to the HP Poly for this go around as I bought a gallon of it for this project. If Enduro Clear Poly is more durable I'll definitely grab that for my kitchen cabinets as the interiors take a beating.

    Are there guidelines for viscosity that I should be following based on the finish and tip I'm choosing, or is this stuff you've just learned what works over time?

  8. #8
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    What GF fails to tell you about the N/N recommendations is they used a pressure assisted gun. I use a 1.3 mm N/N set when spraying HP Poly in my pressure assisted gun, with no thinning. But with the gravity feed set up I had to use a 1.8 mm and thin it 6%.

    Open the "Spraying Paint" document on this page from Homestead Finshing's website: https://homesteadfinishingproducts.c...-pdf-document/ On page 2 is a chart showing the appropriate N/N size for each gun type and viscosity range. It's a good starting point for any kind of finish.

    John

  9. #9
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    Quote Originally Posted by John TenEyck View Post
    What GF fails to tell you about the N/N recommendations is they used a pressure assisted gun. I use a 1.3 mm N/N set when spraying HP Poly in my pressure assisted gun, with no thinning. But with the gravity feed set up I had to use a 1.8 mm and thin it 6%.

    Open the "Spraying Paint" document on this page from Homestead Finshing's website: https://homesteadfinishingproducts.c...-pdf-document/ On page 2 is a chart showing the appropriate N/N size for each gun type and viscosity range. It's a good starting point for any kind of finish.

    John
    Thank you, this is incredibly helpful and stuff I would've never known. Looks like the soonest I can get the Ford #4 is Sunday from Amazon unless I can find something locally before then.

  10. #10
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    Thanks for that document reference, John. Much appreciated!
    --

    The most expensive tool is the one you buy "cheaply" and often...

  11. #11
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    I was going to raise the same question that Jamie did. Distance of gun from surface is pretty critical for almost all spraying, and too far can certainly induce orange peel.
    Fanning the gun at the ends of passes can have the same effect as holding the gun too far away.

  12. #12
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    Yes, that's right, Tom. A year or two ago someone on here posted a link to a guy in Australia or NZ about how to determine the optimum spray distance for any gun and setup. He did it by sound as he moved the gun closer or further away from his hand. I couldn't reproduce it with my own attempts, but distance certainly is a key parameter and one that will change as the gun settings change. You'll here a lot of people say the proper distance is 8 - 10". That's a good starting point for many guns but not an absolute and why you should always shoot some test bursts on scrap or paper to see what the pattern looks like and get the gun dialed in before starting on your project.

    John

  13. #13
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    John, ditto Jim’s comment. I always am impressed with your willingness to share your knowledge re most things finishing. Much appreciated by many of us out here. Best, Patrick

  14. #14
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    Quote Originally Posted by John TenEyck View Post
    You'll here a lot of people say the proper distance is 8 - 10". That's a good starting point for many guns but not an absolute and why you should always shoot some test bursts on scrap or paper to see what the pattern looks like and get the gun dialed in before starting on your project.
    That's about the distance I'm at spraying with a pretty generous fan on the flat piece of mahogany in my current project thread. It's an "art form" to be consistent with this, too!
    --

    The most expensive tool is the one you buy "cheaply" and often...

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    Quote Originally Posted by Patrick McCarthy View Post
    John, ditto Jim’s comment. I always am impressed with your willingness to share your knowledge re most things finishing. Much appreciated by many of us out here. Best, Patrick
    Thanks for the kind words Patrick. Just as I'm appreciative of all I've learned from others, I'm happy to share back what I've learned.

    We're all in this together.

    John

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