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How Did You Teach Yourself to Use an HVLP Unit for Finishing?

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Forum topic by gerrym526 posted 08-19-2021 06:59 PM 709 views 2 times favorited 13 replies Add to Favorites Watch
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gerrym526

331 posts in 5092 days


08-19-2021 06:59 PM

Topic tags/keywords: finishing

Guys,

Just finished building a new shop and am unpacking an Apollo HVLP spray unit I bought years ago but never had space in my old basement shop to use.

I need to start teaching myself how to use it with water-based finishes for furniture and cabinetry I build.

I’ve seen articles recommending starting with water in the HVLP and practicing on cardboard panels-is this a good way to learn how to lay down a finish? Or did you teach yourself using a different method you’d recommend?

It would also help me if any of you have links to articles on using an HVLP.

thanks in advance for the help.
Gerry

-- Gerry


13 replies so far

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Kelly

3872 posts in 4227 days


#1 posted 08-19-2021 07:16 PM

Water is, exactly, how I started out practicing with the HVLP (a 4 stage Titan and an AccuSpray conversion).

One of the things that will go a long ways to making you good is, the right needle for the material you use. For example, a needle you’d use for latex or acrylic paints will not give optimal results with lacquer.

Interestingly, after playing with mine “a bit,” I figured out I could run a small texture gun and avoid packing around a big compressor. Fascinating, since the compressor approach calls for about 45 PSI and around 5 CFM, while the HVLP only puts out about 8 PSI and about 80 CFM.

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JackDuren

1744 posts in 2243 days


#2 posted 08-19-2021 07:17 PM

I ran into a guy spraying poly urethane on case work at a house one day. Asked a few questions and was very helpful. Almost 20 years ago..

It was the magic formula…a few words and I was off…

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Rich

7561 posts in 1873 days


#3 posted 08-19-2021 08:08 PM

Jeff Jewitt has a book that includes video on DVD of spray techniques. I’d be surprised if the videos weren’t available out on youtube or other sites.

Water on cardboard is a good idea. It’ll help you visualize the spray patterns and dial in your flow, etc. If you’d like to start with a really easy-to-spray finish, get some lacquer. Mohawk and Sher-Wood are my favorites, but there are lots of other good choices out there.

Learn to take your gun apart so you understand its operation. Beyond that, practice is everything.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

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SMP

4953 posts in 1189 days


#4 posted 08-19-2021 08:14 PM



Jeff Jewitt has a book that includes video on DVD of spray techniques. I d be surprised if the videos weren t available out on youtube or other sites.

Water on cardboard is a good idea. It ll help you visualize the spray patterns and dial in your flow, etc. If you d like to start with a really easy-to-spray finish, get some lacquer. Mohawk and Sher-Wood are my favorites, but there are lots of other good choices out there.

Learn to take your gun apart so you understand its operation. Beyond that, practice is everything.

- Rich

thanks will check those out as I also need to learn this soon

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CaptainKlutz

5023 posts in 2778 days


#5 posted 08-19-2021 08:24 PM

Wow. I forget how I learned to spray paint? Happened ~50 years ago. :)

Now I remember, painted a 64 Plymouth with my Dad. Mom scraped entire side against a pole at supermarket.
Pretty sure it was school of hard knocks. Every time I made a mistake, Dad would bash me on the head to pay more attention. :(

Learning to spray paint on a vehicle makes things a little easier than wood working. Vehicle gets primer you sand flat, which provides practice. Base coat is not catalyzed and easy to sand out mistakes. By time you get to spray 2-part clear coat, you have practiced twice already on same canvas. :)

IMHO -

Water will teach how most of the gun controls work. Although changing the fluid flow knob with low viscosity fluid like water can be hard to see the differences. Water works well to teach how solvent finish works in gun. You really need to practice with actual finishes to learn nuances.

WB finishes tend to have heavy body, which requires different tips, different pressure/flow, and overlap distances. Will even find differences between different WB finishes.
Many folks find that it easier to learn spraying WB; if they don’t know how to spray solvent paints, as everyone has to learn the new way; and only solvent spray folks have non-WB habits already? LOL

The hardest part of running any spray gun is learning a consistent motion technique. It is much harder to keep the nozzle the exact same distance and angle across a panel, then it sounds. Have to avoid sweeping your wrist in a circle, which changes the spray distance and application volume. Learn to use your entire body to change position while you hold gun at same distance with same angle.

Small projects are more forgiving of poor technique, with primary consequence being runs from too much
material. Large panels separate beginners from amateurs. Large surfaces will show shadows and color differences if overlap, pattern, or spray tip location is not consistent.

Can not learn to spray paint on small piece of cardboard. Need a large refrigerator box, or sheet of plywood/MDF to truly understand how your body motion is related to consistency of film application. Will probably use both side of plywood panel too.

Would estimate that first time I use a brand new finish material, I waste a pint learning how to set up the equipment for the project. And if the temp/humidity changes radically between projects, might have to use another 8-12oz tuning the settings for new environment. When I am done, always write my settings down to reduce the setup time for next project.

Fixturing the objects to be sprayed is important. Can not spray well if you crawling around on the ground, or reaching over head. Set small stuff onto tables, and get ladder/scaffold out for those high spots. You want items to be painted at comfortable viewing angle, and easily accessible. While you are setting up work area, know spray paint goes everywhere. Control air flow to avoid drafts that interfere with consistency. Cover you work area, plus another 20ft. Some paints travel further than others before drying. Have itty bitty red enamel spots on side of my house to prove the above is required, and I was spraying 50 feet away that day.

Having sprayed automotive, industrial, and wood finishes; can say that all three processes behave in similar ways. So most any site, or forum can be OK place to learn basic spray painting.
But best place to learn is from mfg of your spray equipment and finishes used.

Most equipment mfg have videos online showing how to setup and use the equipment. Apollo has nice set of videos online with Boobtube.

The other thing you need to know is that finishes intended for commercial spray application always have equipment and gun setting suggestions for every material. These settings are often proven in high volume mfg sites, and are best place to start. Most also have pro tips for spraying on their web sites as well, but it might not be using your equipment. If your finish of choice does not have product data sheet with spray recommendations, contact mfg. The information may be available by request only. :)

That’s enough babble. Let us know if you have any specific questions.

As Always, YMMV and Best Luck.

-- If it wasn't for bad luck, I wouldn't have no luck at all, Doom, despair, agony on me… - Albert King - Born Under a Bad Sign released 1967

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Mike_D_S

808 posts in 3498 days


#6 posted 08-19-2021 08:49 PM

CaptainK and the others hit a lot of the high points. I’ll add my 2 cents.

1. Spraying water is great for learning how the patterns spray, figuring out overlap spacing, and how to start and stop the fluid flow at the beginning/end of a pass. The best part is that you set the item aside and it dries out ready to practice again.

2. Captain’s comments about fixturing are really important. If you have to contort yourself to spray the piece you may have missed an trick earlier in the process. Tight inside corners? Can you tape off the joinery and finish before assembly? Can you use a stand, hanger, etc to change the profile of the piece to the gun rather than moving the gun to fit the piece?

3. Think about order of operations and plan the spraying, nothings worse than spraying a piece only to realize you need to move it and didn’t leave a place to grab it without touching the wet finish.

4. Viscosity and good mixing really matter. Proper thinning and making sure the finish is properly mixed is really important. I find mixing is really important with paints.

5. Lastly, put together some practice boxes out of plywood and practice with finish spraying inside the box with it on its side. Get some practice with how the finish builds in corners, how the airflow interacts with the finish in tight spaces, etc. Spray the outside and make some intentional mistakes. Spray a flat area until the finish runs, spray too light and come back for a touch up. Get a feel for where the line is between “not perfect” and “bad”.

-- No honey, that's not new, I've had that forever......

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gtrgeo

197 posts in 1713 days


#7 posted 08-19-2021 10:02 PM

Having recently been in your position, I will tell you what I found. I am by no means an expert but this is what has worked for me so far.

- Using water and cardboard will only help you to understand the spray pattern adjustments on your gun. Spraying paint onto cardboard can help set up your pattern but will not give a clear indication of your material adjustment. Cardboard is very absorbent and if you adjust your material setting to the cardboard you will likely find it too wet for the actual project. I keep a square handy when spraying to get a quick check on my pattern and to clear the gun if I have let it sit while repositioning work.

- Learn the feel of mixing thinned paint. You can start with a guideline 10%, 20%, etc. but it will really come down to how the paint flows rather than a specific ratio. Once you determine a ratio for a specific product it may be fairly consistent but you will need to experiment a bit when you change to a different product

- Besides the mechanics of spraying as mentioned above, learn to identify the look of a good coat of wet paint. Set up good lighting while you spray and change your view as you are spraying so you can see what the finish looks like as it is being applied. This can help you adjust your distance, speed, and material flow. Some tend to set to fine of a spray while learning in effort to reduce sagging or runs. In my experience you want to be as wet as you can and still have the coat lay flat to achieve and optimal finish. Fixturing as mentioned above to make sure you are spraying at an optimal angle helps.

- Do not try to overwork the finish. Apply and move on. Going back over a fresh finish in attempt to correct problems will usually end up with larger problems. If it is too light in an area you will get it on the next coat. If too heavy, let it dry. I have had what appeared to be sags starting which will typically disappear when dried.

- Most importantly is to practice. As others have mentioned, get yourself a sheet of plywood or the like and start spraying some paint.

I found this video helpful for learning to thin paint and setup the spray pattern. In the end you will need to do what works best for you on your project.

George

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CaptainKlutz

5023 posts in 2778 days


#8 posted 08-20-2021 05:19 PM

Couple of points not posted:

- Thinning paint for spraying requires some education, and experience. Different guns, prefer different viscosity. Best way to figure out viscosity is by using viscosity measuring cup to learn how changes impact your spray pattern. Lots of online references for this topic. Most material mfg will list a cup type/size and number of seconds to empty cup as range for optimum film build. The range may or may not be right your equipment, but it is a starting point, and cross reference tables are available to compare different cup types/sizes.

A #4 Ford cup, or a Zahn #2 are good tool to own, so you can learn how to thin a finish. Can find plastic #4 Ford cup for < $10. After a while, you won’t need the cup and can eyeball paint flow; and that is a good thing.

- Need to own and use wet film thickness gauge.
Simple plastic versions are cheap. Many commercial finish supplier offers them for free with decent sized purchase, with their name/phone number on it as marketing tool.
Can see the different types on bottom of this web page: https://www.gardco.com/filmthickness.cfm
Use a wet film gauge when practicing with any new material, so you can learn optimum film build.

There is little bit of a dance trying to figure out all the variables the first couple of times. Each time you spray a project, or use new material; the next ‘new’ spray adventure gets a little easier.

+1 When you see a run or foreign material defect in wet paint, do not try to fix it.
It takes a very skilled hand to fix them, and not make it worse.
Instead buy some paint ‘Nib’ Files. Several companies sell them. Here is one example. Nib files are used to shave of high spots, or bugs/dust that got into the finish.. Works much better than sanding, as might not even need to re-touch the paint. Just wax/buff and leave it alone. :)

Cheers!

-- If it wasn't for bad luck, I wouldn't have no luck at all, Doom, despair, agony on me… - Albert King - Born Under a Bad Sign released 1967

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MrUnix

8799 posts in 3482 days


#9 posted 08-20-2021 05:22 PM

Wow… lots of people writing books above to basically say “Practice, practice, practice” ;)

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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EarlS

4804 posts in 3631 days


#10 posted 08-20-2021 06:32 PM

Not sure if this was said. I started spraying with the rattle cans. That taught me how to spray. Moving to HVLP, I had to learn how to set the needle for the best spray and how to deal with things like the hose. I didn’t do a lot of practice with water, mostly learned using minwax polyurethane. A couple of times having to sand orange peel down, or runs, drip, and sags, and you pay a lot more attention to the whole process.

Most important thing I learned is not to put it on too thick or come back to put just one more layer on. I suppose prep is also something that kind of gets missed. Sanding to the appropriate grit, wiping down the surface, and knowing how you intend to spray the piece is as important as knowing how to set the spray and the details about the finish being used.

+1 – practice

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

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Kelly

3872 posts in 4227 days


#11 posted 08-20-2021 07:09 PM

Good advice, Earl. The rule is, two coats are far better than one, with exception made for some unique, specialty finishes (we’d put Geko (?) on cold storage walls. It could go on about 1/8” thick without dropping.

Another thing to remember is, you’ll have to change settings, both fan size and flow rates, for the same product when you change applications.

For example, I’ve used my quart gun to spray a short run of fence. Then, on the same job, narrowed the fan down to spray balusters on a stair (the HVLP cut the paint time down from up to a couple days to just a few hours).

In the end, it doesn’t take much playing to get a feel for what you need.

Even on jobs, we had cardboard or something we could test drive the output on before we went all in.

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Kelly

3872 posts in 4227 days


#12 posted 08-20-2021 07:12 PM

Translation (?): Telling the OP what to practice.


Wow… lots of people writing books above to basically say “Practice, practice, practice” ;)

Cheers,
Brad

- MrUnix


View Robert's profile

Robert

4785 posts in 2764 days


#13 posted 08-20-2021 09:35 PM

No expert here at all, just what’s worked for me.

Forget the cardboard. You can look at the pattern by simply holding the sprayer up. You need practice boards and some air time. Get some 2×4 pieces of plywood or MDF, spray some primer on it like BIN shellac, sand it smooth.

What paint are you spraying? The only water based paint I have sprayed are pigmented lacquer (Target Coatings) and Pro Classic (Sherwin Williams)

Getting the paint thinned correctly for your tip is the learning curve. You can use a Ford cup, but I’ve found if it goes through a medium mesh strainer about as fast as I can pour it then its right.

Then try painting. If you’re using an HVLP don’t use a thick paint that requires a lot of thinning. You need a 1.3mm tip for top coats.

The gun is everything. Run some acetone through yours to clean it out.

-- Everything is a prototype thats why its one of a kind!!

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