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A case for spraying finishes #1: Spraying Finishes, Lacquer and Gravity Feed HVLP

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Blog entry by pintodeluxe posted 12-13-2010 10:24 AM 3046 reads 1 time favorited 2 comments Add to Favorites Watch
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1. You will use much less material because the transfer efficiency is higher.
2. Less noxious overspray.
3. Better finish with no orange peel. Actually it is glass smooth, and seems almost automatic to get perfect results.
4. If you accidentally run the cup out of finish, it just quietly stops spraying. Compare this to the sputtering mess created by a siphon gun.
5. Two coats of lacquer with the gravity feed = three coats with the siphon gun. I measure this both in terms of how much finish is being laid down, and the quality of the end result. After one coat with the gravity feed gun, the finish already feels pretty smooth. A quick sanding with a very fine (220 or so) sanding sponge, followed by vacuuming with a brush attachment and wiping down surfaces with a cheesecloth (not a tack cloth) is all that is needed to prepare for the final coat. The second coat should be a moderate wet coat. After the second coat, the lacquer develops a nice satin luster. If any minor dust nibs remain, wipe the piece with a dry towel after the lacquer is fully dry. I can lacquer a piece from start to finish in one evening after work if the temperature is 45 degrees or higher. Because the lacquer is not overly thinned, you won’t have any runs or sags in the finish.
6. You can spray horizontal or vertical surfaces with great results.
Brush vs. Spray? I say spray wins hands down. Read my review of the Porter Cable PSH1 for more info.
Cheers.

I recently read a woodworkers journal magazine dedicated entirely to finishing. I was surprised that spraying wasn’t discussed until the end of the issue. There is an assumption that spray equipment is too expensive for hobby level woodworkers, which used to be true. There are still expensive systems out there with dedicated turbines, but you don’t have to go that route. In fact many reviews state that the $600 HVLP systems are not much better than the less expensive models. But you have to buy the right equipment based on the finish you will be spraying. I use an airless sprayer for latex paints and exterior stains. Airless sprayers are still champ for big jobs such as these. A 512 tip will cover most common needs here. Double the first number for your fan pattern width ie 5 = 10” fan pattern. The last two numbers are the spray tip aperature size. The larger the number, the more fluid will be delivered. Cost for a good airless sprayer is now less than $200.
I believe in having dedicated sprayers for different finishes. Nothing would be more frustruating than having your house paint dissolve in your lacquered furniture project. With that in mind I use a siphon type HVLP gun for spraying stain. Almost any compressor will run it, and you already own one of those. A moderate quality gun will work fine here, because you will wipe the stain off after spraying. Therefore the spray pattern is less critical. I use a Craftsman “HVLP” siphon gun, and the stock needle and tip spray stain just fine. Siphon guns are available for $50-100.
I view spraying clear finishes as the most critical application, so you will want to use your best gun here. I really like the Porter Cable PSH1 gravity feed HVLP gun. It runs off your compressor just like the siphon guns, however now HVLP really means low pressure. This gun only needs 30-35 psi at the gun to spray lacquer. I thin my pre-catylized Miller brand lacquer with 20% lacquer thinner. The gun comes with a 1.5mm nozzel which is perfect for lacquer. I have had great luck with that product, as well as Sherwin Williams Pre-Cat, and Magnalac Pre-Cat. I now buy Miller because it is only $30 per gallon. I have noticed some distinct advantages with the gravity feed HVLP over the siphon HVLP:

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush



2 comments so far

View grandpasworkshop's profile

grandpasworkshop

344 posts in 2526 days


#1 posted 11-23-2012 04:00 PM

Question
I have a Harbor freight gun that I thought I would start with, Have not used it yet and weather is getting cooler ,Would I be able to practice the settings using water inside my small shop to get used to fan width etc??

-- Grandpaj

View a1Jim's profile

a1Jim

112882 posts in 2324 days


#2 posted 11-23-2012 04:22 PM

Good info Willie
That’s exactly what I have my students do Grandpa. I’ve been spraying for 30 years after you get it you never loose it. Practice makes perfect.

-- http://artisticwoodstudio.com Custom furniture

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