# Argghhh.. can't get HVLP gun to spray oil primer properly...



## BNB187 (Mar 10, 2019)

Hi,

I've recently purchased a Fuji Minimite 4 with the T75G gun. I used this setup to do my kitchen cabinets. I'm having huge problems spraying oil-based primer. I've tried to spray Sherwin Williams Extreme Block multiple times now and can't get decent atomization. I've thinned it to what Fuji recommends for the given tip. I've been using a 1.8mm tip and thinned it with mineral spirits so that it runs through the viscosity cup in about 45 seconds, which is only about a 10% thin. I've tried a 1.5mm tip at that viscosity, no real change. The finish comes out pebbly and ends up very grainy, I'm not sure I would call it orange peel but similar. 

Conversely, I spray thinned latex with the same tip and much thicker, thinned by about 20% and running through the viscosity cup at about 80 seconds and I get really nice results, good atomization, paint levels well, no complaints. 

At the end of the day it is just primer and sands easily, but sure seems to be a waste of time to have to sand it down enough. It's definitely not a quick scuff sand, have to remove a fair bit of material to get a smooth finish. 

Any help would be appreciated, I guess my next thought is to thin it even further and see what happens. Or should I just abandon oil-based and go to shellac-based primer?


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## Tony B (Jul 30, 2008)

One thing you can do is look on the Product Data Sheet for your SW primer. Usually they will recommend how much thinner to use with a 'not to exceed x %".
It's the finish manufacturers recommendation as to the amount of thinner to use, not the gun manufacturer.

Another thing to try is a bigger tip.
It's the gun manufacturers recommendation as to which tip to use for a given viscosity.

Then there are times when nothing seems to work and that's when you give it just a little more thinner - on a test piece to see what happens. If this exceeds the finishing product manufacturer's specs, call the manufacturers Tech Support and talk to them about thinning and what you are up against.


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## DrRobert (Apr 27, 2015)

It could be a settings issue or you may need to thin it some more. I usually find this is the issue. I don't pay any attention to data sheets, I just thin until it sprays well.

But before you do anything, double check and be sure the gun is thoroughly cleaned and adjusted properly.

Separate issue, but I've gotten totally away from oil based paints. Partly from the clean up standpoint, but mostly because I can do 2 coats sanded and ready easily in one day. I use shellac based BIN primer almost exclusively.

For topcoast I use water based pimented lacquers. I really like the Target Coatings product. For kitchens you can use the crosslinker additive which believe brings it up the KCMA standards. Again I can often do multiple coats in one day.


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## woodnthings (Jan 24, 2009)

*Thanks for the tip ....*

I found several tests on the water based Target Coatings, brands Emtech:


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## GCTony (Apr 5, 2018)

DrRobert said:


> Separate issue, but I've gotten totally away from oil based paints. Partly from the clean up standpoint, but mostly because I can do 2 coats sanded and ready easily in one day. I use shellac based BIN primer almost exclusively.
> 
> For topcoast I use water based pimented lacquers. I really like the Target Coatings product. For kitchens you can use the crosslinker additive which believe brings it up the KCMA standards. Again I can often do multiple coats in one day.


It's very rare for me to spray oil. Not only the time with slow drying but the longer the finish is tacky the more dust to settle on it. When I do spray oil, it's HVLP air at around 40 psi, thinned maybe 15%. The turbine systems just don't have the pressure to atomize the oil unless it's thinned way more than what the product data will allow. The science has gotten so good that we don't even use BIN (alcohol based) very often. 

I also top coat with water borne lacquer but I don't use Target anymore. Since we're mostly a commercial user we prefer Sherwin Williams Kem-Aqua or ML Campbell Aqualente which I believe are better all around products in addition to large companies with great customer support systems. Not bashing Target, their products are fine, probably the most forgiving, easiest to spray but I guess I've outgrown them.

The OP; if oil is your choice thru the turbine; I would try increasing the thinner along with some Japan Dryer. The 1.8 is part of the "orange peel" problem. I personally would try to dial in the viscosity to the 1.5.


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## Rebelwork (Jan 15, 2012)

I usually keep thinning till it will spray. Once you find the right amount you should be on your way...


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## B Coll (Nov 2, 2019)

I have the same Fuji gun and a Graco 4 stage. I have struggled with the same issues (not oil based though). I recently had the problem using Targets high solids primer/filler. I think I would have had more success if I thinned the primer a bit more and pushed it through a 1.3 mm setup. My go to primer has bin BIN Shellac based. Sprays perfectly, sands like powder. I think I am going to stick with that.


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## BNB187 (Mar 10, 2019)

GCTony said:


> It's very rare for me to spray oil. Not only the time with slow drying but the longer the finish is tacky the more dust to settle on it. When I do spray oil, it's HVLP air at around 40 psi, thinned maybe 15%. The turbine systems just don't have the pressure to atomize the oil unless it's thinned way more than what the product data will allow. The science has gotten so good that we don't even use BIN (alcohol based) very often.
> 
> I also top coat with water borne lacquer but I don't use Target anymore. Since we're mostly a commercial user we prefer Sherwin Williams Kem-Aqua or ML Campbell Aqualente which I believe are better all around products in addition to large companies with great customer support systems. Not bashing Target, their products are fine, probably the most forgiving, easiest to spray but I guess I've outgrown them.
> 
> The OP; if oil is your choice thru the turbine; I would try increasing the thinner along with some Japan Dryer. The 1.8 is part of the "orange peel" problem. I personally would try to dial in the viscosity to the 1.5.



I'm not sold on oil by any means, I've relied heavily on what is out there on the internet in choosing the primer. My biggest concern is what will work best with the equipment I have and blocking tannin bleed through. The consensus seemed to be either oil-based or shellac for their ability to block stains and tannin bleed through. If you have a suggestion on water-based products that would be acceptable for this I'm all ears! I do occasionally work with cedar and have seen people struggle mightily with bleed through working with it. I remember when I was a kid we had a cedar fence that my mom painted every year for half a decade and it would bleed through every time. 

If there is a water-based product that will have similar blocking characteristics I'm in!! Easier cleanup would be great!! I don't have a problem applying an extra coat of primer to get a result with a water-based product that could be achieved with a single coat of oil or shellac.

Thanks


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## BNB187 (Mar 10, 2019)

Tony B said:


> One thing you can do is look on the Product Data Sheet for your SW primer. Usually they will recommend how much thinner to use with a 'not to exceed x %".
> It's the finish manufacturers recommendation as to the amount of thinner to use, not the gun manufacturer.
> 
> Another thing to try is a bigger tip.
> ...


The PDS for SW Extreme Block states to not thin at all for stain blocking. Not really looking for traditional stain blocking, more concerned about tannin bleed-through in most of the work I do.  They don't offer any advise as to thinning at all. I've sent them an email requesting some help. I will see what happens. I guess what I'm struggling with is the fact that I can push much thicker latex coatings through the 1.8mm tip and have great results. So I can't get it through my thick head why the oil-based is causing me this grief.

I agree that finish manufacturer would be a better place to start with recommendations for thinning, but at the end of the day I need to make it work with the equipment I have. So if I have to push past their recommendations to get the result I desire I'm likely to do that.


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## BNB187 (Mar 10, 2019)

B Coll said:


> I have the same Fuji gun and a Graco 4 stage. I have struggled with the same issues (not oil based though). I recently had the problem using Targets high solids primer/filler. I think I would have had more success if I thinned the primer a bit more and pushed it through a 1.3 mm setup. My go to primer has bin BIN Shellac based. Sprays perfectly, sands like powder. I think I am going to stick with that.


I think that BIN shellac will be my next product to try, unless someone has a suggestion of a water-based product that works well for tannin blocking in particular. Are you thinning it to spray or right out of the can? Any recommendations you can give me for using this with the Fuji is greatly appreciated. I assume cleanup is done with alcohol? Is methyl-hydrate acceptable to thin and or clean up with?


Thanks


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## B Coll (Nov 2, 2019)

If you are not using BIN alcohol, what are you using for a primer? I used Target HSF5000 on my last paint grade project and was not thrilled. Probably was on me, perhaps should have thinned it a bit more. I would love to now of a good spray-able primer that sands to a nice powder without gumming.


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