Author Topic: Failed HVLP attempt, Advice?  (Read 7009 times)

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Offline 3PedalMINI

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Failed HVLP attempt, Advice?
« on: March 24, 2019, 09:26 PM »
Im spraying a cabinet using my Fuji MM4 and T75g gun. Using Emtech HSF5000 Primer. Tried with 1.3 and 1.8 and had a horrible time. It was confirmed a few times from the supplier and reading online that I did not need to thin the primer. I got a very blotchy spray (spitting isnt the right word, but kind of similar) I could not get it to lay nicely. Now the cabinet is "bumpy" Not a HUGE deal because obviously I have to sand anyway but the finish overall is terrible. My garage was 67 degrees and 50% humidity. Im thinking this did infact need to be thinned?

to say im a noob at spraying HVLP is an understatement. Im now really nervous about shooting the Emtech 6500 with HVLP. Thinking to finish this cabinet I should shoot it with my airless sprayer and practice getting the gun/paint viscocity correct on some scraps after its out of the shop.

I stupidly went forward with spraying hoping things would get better. Not a huge deal since it was primer, but now I have more sanding todo.
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Offline Mike Goetzke

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Re: Failed HVLP attempt, Advice?
« Reply #1 on: March 24, 2019, 09:50 PM »
I’m not an expert either but I’ve always needed to thin Target coatings finishes with my Q4. I’ve also had better luck with more airflow and smaller tip. I suggest practicing on a scrap board.

Mike

Offline 3PedalMINI

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Re: Failed HVLP attempt, Advice?
« Reply #2 on: March 24, 2019, 10:07 PM »
I’m not an expert either but I’ve always needed to thin Target coatings finishes with my Q4. I’ve also had better luck with more airflow and smaller tip. I suggest practicing on a scrap board.

Mike

Interesting. I guess I should have not taken the paint stores word and what I found online about thinning. Would you say what I experienced was due to not thinning? I’m trying to find a picture that best shows it. Maybe when I try again I’ll take a picture.

I did have some scrap plywood pieces to try first. I should have just quit and asked on here. It’s a project that is long overdue and im excited to finally be done with it.
The Bitterness of poor quality remains long after the sweetness of low price is forgotten -Benjamin Franklin

Professional Custom Audio Video System Designer/Installer serving Southern - Middle NJ, Eastern PA & the Surrounding Shore Points.
www.sigsv.com

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Offline tjbnwi

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Re: Failed HVLP attempt, Advice?
« Reply #3 on: March 24, 2019, 11:07 PM »
Put the gallon can in a pot of 100° water. Allow gallon to warm. Fill the cup, place the can back in the water, spray, repeat.

Tom

Offline Pnw painter

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Re: Failed HVLP attempt, Advice?
« Reply #4 on: March 25, 2019, 01:14 AM »
I’ve found that things only tend to get worse and not better when I’m spraying.

Tom’s advice about worming up the paint might make a huge difference. The viscosity of some paints at can really be effected by cold temps.

On a recent project I’d leave a gallon of paint sitting on a heating pad over night to ensure it was ready to spray the following morning.


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Offline blaszcsj

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Re: Failed HVLP attempt, Advice?
« Reply #5 on: March 25, 2019, 12:04 PM »
Check it with the viscosity cup that came with the gun and review the times against what it says in the manual. For doing thicker paints, the book also recommends removing the black ball valve for the incoming air at the bottom of the gun. It allows for no restriction and highest flow.

hope this helps. The manual recommendations actually work pretty good.
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Offline mschmidt10k

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Re: Failed HVLP attempt, Advice?
« Reply #6 on: April 23, 2019, 10:26 AM »
With a Fuji MM4, there's no need to thin the Emtech HSF5000 at all - I spray it with a 1.3 cap and it lays down easily. Did you try it out on a practice board beforehand so you could set the spray pattern/air flow?

Offline sheperd80

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Re: Failed HVLP attempt, Advice?
« Reply #7 on: June 14, 2019, 10:11 AM »
Ive been spraying with my mm4 alot lately and found that all the factors you hear about do matter quite a bit. Material temp, air temp, tip size, viscosity, and how much you put on in one coat. When spraying onto a piece of scrap you wanna see a very fine mist around the edges of your spray pattern. If there are even small spots, somethings wrong. Viscosity will vary in different climates but timing your material in the provided cup will get you to the right tip size. For finer finishes i never want to use higher than the 1.5 tip, even with latex. Preferably 1.3 or even 1.0 depending on the material.

I recommend thinning to a viscosity that works with a finer tip. Once your spray pattern starts to look good (small mist, not splats) dry time is the next obstacle. Not familiar with wb lacquer but with pigmented precat i always add retarder to give the material time to flow out in my warm climate. If the material is dry by the time you sent the piece of side on a drying rack, that's obviously driving way too fast. It should look wet for at least a few minutes

And finally, make sure youre putting enough material down. This is a hard thing to judge and harder to describe. One way to guage this is to spray a vertical scrap piece until it just starts to run. Then do another slightly less until it looks like it could almost run, paying attention to how fast your passing over the piece. This is roughly the right amount for most paints. Then of course spray your parts horizontally whenever possible, aiming for that wet coat that would almost run if it were vertical.

Not an expert, but ive been hard at it lately and getting decent results. Hope this helps.

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« Last Edit: June 14, 2019, 10:20 AM by sheperd80 »

Offline sheperd80

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Re: Failed HVLP attempt, Advice?
« Reply #8 on: June 14, 2019, 10:14 AM »
My current project. This is only the 2nd coat. Obviously still has some defects and wood grain showing but the third coat should look pretty good.

Rudd duracoat precat, 4% retarder.

This is shown from a harsh angle, under harsh light. From Straight Ahead this looks nearly perfect
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« Last Edit: June 14, 2019, 10:18 AM by sheperd80 »

Offline jobsworth

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Re: Failed HVLP attempt, Advice?
« Reply #9 on: June 14, 2019, 12:17 PM »
I do what Tom suggested on colder day using my W/B finish. So if yer having a issue with the finish not flowing, I would try warming it. If its to warm out side then you may want to try a retarder to slow the drying of the material. When I spray thicker material like Behr outdoor seal stain sealer I use a much larger air cap, nozzle ad needle. (apollo) It would be a C air cap for thick material and a 2.0 ( could be larger havent used it for a while and Im still chilling in the quiet of the morning ) nozzle and needle.

So my suggestion is to the customer service of the gun yer using and ask them what N/N they recommend for tht material. You may not need another one but it doesnt hurt to check . At least thats what I would do
« Last Edit: June 14, 2019, 12:25 PM by jobsworth »