Thinning down SW exterior paint for HVLP

[bradleyheathhays]

Just got myself a gravity feed 1000ml cup HVLP spray gun and I'm preparing to shoot some exterior bright white semi-gloss on some cedar sticks that'll be part of an garden trellis. Although the finish doesn't have to be anywhere close to perfect I'd like to see it go on as best it can, if for no other reason than to improve my skills for more demanding paint projects. I called SW for the spec sheet and they helped me translate what mm size number 3 and 4 needle size translated to, so that's fitted on the gun, 1.7mm I think. What I was surprised to see is that the sheet advises applying as is, no dilution. Although I have very little experience using HVLP I was almost certain most all paint needed to be thinned down to be applied this way, especially thick stuff like what I have.

Any recommendations on how to go about this paint application? What to dilute with and how much? Like saying, I'm new to this so all advice is appreciated.

PS When I was first asking about what to dilute with he reviewed his literature which explained 'it behaves like water' insofar as clean up is concerned, but also has alkyl properties. I suppose that has something to do with why they charge a hundred bucks a gallon for it. And to answer your question/expletive...it was the customer's request actually. I'll be switching to a much less expensive grade for my own projects.

 

[Tach]

I spent the first 30 years of my career behind the counter of several different paint manufacturers, including SW. The one suggestion I would make is to use a product called Floetrol, if you can find it. It is a product for water-based paint conditioner. It will lower the viscosity and allow a smoother finish. It will allow the paint to flow better thru the HVLP and doesn't actually dilute the paint. You may find that you will need to add some water also, but it should not be significant. Keep in mind that even though the transfer efficiency of an HVLP is quite high it still uses air for atomization and will require multiple coats. An airless sprayer would allow you to spray even thick coatings in one coat because it uses fluid pressures that are much higher and basically shears the material through a small orifice. You would not even need to thin the paint at all with an airless system. Most manufacturers data pages base application using airless which is why they do not mention thinning.

I read where you are using cedar. I would recommend some type of blocking primer prior to the topcoat, especially white. Cedar will usually bleed through most water-based coating because the tannin is water based. You may want to check with SW for a recommended primer for cedar. I would hate to see your nice bright white turn yellowish in a short time.

Best of luck.

 

[bradleyheathhays]

Hey thanks Tach. That's the first recommendation I've heard for blocking tannin. Would regular killz do the trick? I think it thins with water so maybe not? I'll give SW a call to see what they have to say. I'd sure hate to see my work going yellow too!

Sorry I thought the data sheet specified the exact paint I was using. Apparently not. Here it is..

 

[Tach]

Hey thanks Tach. That's the first recommendation I've heard for blocking tannin. Would regular killz do the trick? I think it thins with water so maybe not? I'll give SW a call to see what they have to say. I'd sure hate to see my work going yellow too!

Sorry I thought the data sheet specified the exact paint I was using. Apparently not. Here it is..

View attachment 369388

That is supposed to be a really good product. I haven't worked in a store since 2013 so I am not as familiar with their homeowner style coatings. I am currently working in water/wastewater using SW Protective and Marine coatings.

 

[jeff]

I've sprayed that product with HVLP on furniture and thinned about 10% with water and added 8oz Floetrol per gallon (as instructions suggest). Layed down nice, recoated well after an hour and I was happy with the result. I would definitely use an oil-based primer on raw cedar for outdoor use. Speaking of Floetrol, I use it on brush work too. Seems to really improve the finish.