Spraying minwax high build polyurethane?

[Michael Dunn]

Hey guys!

My apologies if this has been discussed anywhere. I did perform a search and couldn't find any info. I have the Graco Magnum X7 and would like to know if there is any oil based minwax products that can be sprayed.

I'm well aware that Minwax claims they have zero products that can be thinned and sprayed. That is except for their aerosol cans. Is there any way to spray Minwax's High Build Polyurehane Clear Semi-Gloss?

I typically use GF products but this particular client specified Minwax golden oak. Can I simply thin the Minwax Poly with MS and spray? The guy at GF said I could, but decline to offer any thininng ratio. Minwax flat out claims none of their products can be thinned or sprayed.

I find that hard to believe. I know I've read about people doing this before I never paid attention to the specifics due to not spraying often.

Any thoughts?

[Art Mann]

I don't know if this will help since I don't use an airless sprayer. I have thinned and used regular Minwax Semigloss Polyurethane successfully with a HVLP conversion gun. It would not be my preference but I know it can be done. I would experiment with thinning it up to 10% before working on the actual project. Sometimes, you gotta do what you gotta do.

[John TenEyck]

Michael, I'm sure you could thin the MinWax product by adding whatever is specified as the solvent for clean-up until you get the correct viscosity for your sprayer, but I wouldn't do it. When you spray solvent based varnishes, like MinWax, the aerosol stays sticky and makes a mess on whatever it lands on. Unless you do it outside, and not on the driveway, you will have one heck of mess indoors. And if you do it outside, the workpiece will attract whatever dust, bugs, etc. happen to come by for an hour or two until it sets. To get the look the customer wants, I would spray toner coats of Sealcoat shellac with Transtint dye added to it, and then topcoat with a WB product. No mess, and fast, too. I do this all the time in my basement shop using a temporary spray booth vented to the outside with no filters. Works in a garage, too, with just drop cloths.

John

[Michael Dunn]

If I do go with a WB top coat how long should I wait for the oil based minwax stain to dry... Its already on there. Again, I need to better prepare my finishing schedule. I have quite a few other non woodworking projects I'm juggling as well over here. My mind is melting...

[Prashun Patel]

They dont recommend thinning because it violates voc laws, not because it cant be done.

You can thin it with naphtha or ms as much as you wish. That is how wiping varnish is made and is why wiping varnish cant be sold in gallon sizes in most states.

You can also use any oil based finish over that oil stain.

If however u havent sprayed ob poly before, i would research the caveats first. It can be done successfully, but i HEAR it can be frustrating.

[Michael Dunn]

Well, for this job Ie'v decided to brush the clear coat on. So far so good. I mean I'm still in the driveway doing it, but it looks good and so far no bugs that I can see. Thanx for the tips.

I'll continue to NOT use Minwax for most projects as always. I always used to use Minwax, then I heard about GF. Nuff said.

[John TenEyck]

Depending upon the temp., a minimum or 48 hours, 72 hours is better. I've used a lot of GF WB clearcoats over oil stains and never had any problems as long as I wait long enough for the stain to completely dry. You also can put a coat of Sealcoat shellac over the stain first, but the stain still has to be dry, so I never have. I know you've already moved on with this project, so just file this in memory for another project.

John

[Art Mann]

My reservations about spraying Minwax Polyurethane are the same as John's. It takes at least a couple of hours to dry to the point it isn't tacky. Contamination is going to be a problem even in a favorable environment. I was going under the assumption that the customer was forcing you to use Minwax. If you can use something else, solvent based laquer is also a possibility. I'm not totally sure the airless sprayer will work at all. My experience with hand held airless sprayers applying fine finishes has been poor. Maybe the Graco will work better.

[Jim Becker]

Yes you can spray it. But...spraying slow-drying varnish is a thankless process since all the overspray is very, very sticky. Spraying is best for finishes that have a fast dry time so you can re-coat frequently and move on.

[Howard Acheson]

Any liquid finish can be sprayed. That said, some behave well when sprayed and some don't. All oil based varnish or poly varnish is slow drying and shares the difficulty of having their over spray in the form of liquid droplets or mist. This mist floats around in the air and anything it lands on will end up with a "crust". Oil based finishes should only be sprayed in an effective spray booth or the over spray will get on everything.

If you want to spray Minwax oil based poly, I would thin it about 30-50% with mineral spirits. Test how it goes and make adjustments to your gun and equipment.

[Art Mann]

Has anyone successfully used an airless sprayer like the Graco Michael mentioned that appears to be designed to spray house paint? MY experience with doing that was bad. Maybe that is a type of equipment I am unfamiliar with.

[Matt Cook]

A little late...I've sprayed a ton of MW semi through HVLP and it has worked great! I'm running a 1.5 needle unthinned and I can lay a heavy first coat to seal, barely scuff with 220, and lay a clean finish coat ant it looks beautiful. Scuf and add a third and it builds deep. And by a lot, I mean a lot. My entire shop setup is sprayed ploy. Here's a sample

mebu2uma.jpg

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Still working on the last two missing at the end above (shot the yesterday)

saveseju.jpg

Now originally I was concerned about crap getting in the finish in the time it takes to dry but I get amost none. Dunno why. I spray a side on the side of the house and immediately bring it in and stack them in makeshift piles so they can dry and leave them until they are dry enough to scuf or hang. Now the side of my house is a beautiful location though. There's never any wind on that side. Can't explain it but there isn't. As for how long to dry...some days it was hours and others took much longer. It all depended on the airflow in the garage, the temp, and the humidity. I never timed it, just let it take what each coat took.

a5avyzaz.jpg

Obviously after the number of drawers, drawer fronts, doors, and cabinet faces I've gotten the hang of how much I can lay down without running but it didn't take long to figure it out. Even when I did get a run I just used a razor and cut it off, scuffed the surface, and shot it again. If you can see the wet edge and control the gun, it's really fairly easy. Once inside I have a few fans that blow from the back of the grange forward and keep the garage door about 1/3rd open all day. We've never smelled it in the house.

heres a shot of some of the drawer fronts. Screwed them through the pull holes to some ply with some standoffs so I didn't have to shoot them all individually. Just an idea for time savings if you end up spraying.

huhydyga.jpg

I'd recommend it if you have a safe place to spray. Oh...I wear a mask when I brush, spray, inspect during drying, always. As others have said, very nasty stuff.

[Matt Cook]

So I've had a reflective moment. Based on some research I found that the 1.5 needle sized HVLP might be a tad small and running a 1.8 might change things so I ordered one. The difference is substantial. I get nearly no aresoeled poly and almost all of the material is going on the surface. Coatings are now also much faster since the transfered volume is greater. Runs happen quicker so I have to pay more attention but if I keep my speed and overlap consistent, I can avoid them. Wish I had every needle size. Might be fun to see what a 1.7 would do.

[Jason Roehl]

Has anyone successfully used an airless sprayer like the Graco Michael mentioned that appears to be designed to spray house paint? MY experience with doing that was bad. Maybe that is a type of equipment I am unfamiliar with.

Years ago, we were hooked up with a log home builder, so we sealed the inside and outside of many log homes. Insides were sprayed with waterborne polyurethanes, except once. One we did was built prior to our tenure, but the homeowner wanted their high-ceiling living room re-sealed. With oill polyurethane. Thankfully, I was on other jobs at the time, so not part of that endeavor. My cohorts put plastic down and over everything (the room was furnished and carpeted!), then went nuts with an airless sprayer. They ended up walking around in socks, sticking with each step, sticking to everything they touched, coated in a gooey layer of poly and having to take a rag bath with mineral spirits when they were done.

I don't know that I could have done it. I can be sweaty, muddy, dirty and greasy (and have been all of those from head to toe in spades), but I loathe sticky.

[phil harold]

I typically use GF products but this particular client specified Minwax golden oak.

Minwax golden oak is a stain you can use other finishes on top of it...