LumberJocks

First time hvlp finishing questions

  • Advertise with us

« back to Finishing forum

Forum topic by rut posted 03-10-2012 01:33 AM 1253 views 0 times favorited 5 replies Add to Favorites Watch
View rut's profile

rut

81 posts in 1847 days


03-10-2012 01:33 AM

So I splurged (actually went cheap) and picked up a rockler hvlp system for about $100. After reading all of the great reviews I figure it would be worth it for the learning experience.

Unfortunately, the instruction sheet is minimal. It came with two needles (valves), one smaller than the other but no sizes labeled on either that I can see.

So I’m wanting to spray water based polycrylic finish and I’m assuming I need to use the larger tip. Just wondering if anyone has any experience with this unit and spraying this finish. Does it need thinning? Any tips would be appreciated.

Thanks,
Rut


5 replies so far

View JAAune's profile

JAAune

1643 posts in 1782 days


#1 posted 03-10-2012 03:25 AM

You’ll need to spray some test samples to see how the different tips work. The general rule is that you want the smallest tip and needle that will still permit the finish to flow freely. Thicker finishes require a larger tip. If you can’t get a decent spray to come out, use the bigger needle. If the finish comes out as droplets instead of a mist, go to the smaller tip.

It’s best to avoid thinning water-based finish if possible. If it must be thinned, the can usually tells the maximum amount of water that can be added. Putting too much water in may mess up the performance of the special blend of solvents used in water-based finishes. I don’t remember what the maximum thinning ration for Polycrylic is.

Warming the can of finish on something like a coffee cup warmer will improve flow as well.

-- See my work at http://remmertstudios.com and http://altaredesign.com

View JohnnyM's profile

JohnnyM

39 posts in 1798 days


#2 posted 03-10-2012 06:52 AM

I have the same unit from Harbor Freight. It works really well for the price. As JAAune says, try the different needles and see which flows your finish best. I started with my adjustment knob all the way in and start backing it out until I got the pattern I wanted. Then I looked at the coverage of the pattern to see if it was the coverage I wanted. Once dialed in, I can spray water based General Finishes right from the can with no thinning. I made note of which needle works best and how many turns of the knob so after cleaning I can put it right back to the settings that work for the finish.

-- ~~ John . . . . . . . . . Against the Grain Woodworking & Design, LLC

View rut's profile

rut

81 posts in 1847 days


#3 posted 03-11-2012 02:17 AM

So I gave this a try today. I’m not real sure that I did it correctly. I had no runs but I’m not sure how to tell if I’m putting enough finish on it. Is it better to do a light spray and then go back over with a heavier coat? Or do you just do a heavy coat to begin with?

I found it difficult to actually see the finish coming out. I sprayed it using the smallest nozzle and unthinned.

Rut

View JohnnyM's profile

JohnnyM

39 posts in 1798 days


#4 posted 03-11-2012 05:15 PM

I always try to spray the same amount of finish on every time. I don’t spray a light coat and then a heaver coat. If you are covering the surface without any sags or runs in your vertical surfaces it is a good coat. Not a complete covering then it is too light of a coat. Sagging or running is too heavy of a coat. Check your coverage while the coat is still wet. On the first few coats the finish will be absorbed as it drys so it may not look like a nice even coat. Subsequent coats will will dry on the surface. Remember your gun settings so you can repeat it next time you use that finish.

-- ~~ John . . . . . . . . . Against the Grain Woodworking & Design, LLC

View Trapshter's profile

Trapshter

64 posts in 1859 days


#5 posted 03-12-2012 12:10 AM

Rut use water with food coloring . Spray cardboard get the feel for material and air flow combination. Based on the amount you paid for the unit . I will assume it’s a single stage turbine. So your air flow is what it is . You should have a material flow adjustment . With it screwed all the way out so your trigger is fully depressed. While holding your trigger start to screw the material knob in until you feel the trigger start to close. This is your max setting. Let’s start there spray the water see how much comes out on your cardboard .spray a fifty % overlap down the piece of cardboard. Keeping the gun about 6-8 inches from the surface . See how you do. If it’s too much material ,dail the gun down a little . Keep going until you have the right amount of material coming out still keeping a wet on wet coverage. If you have too much as mentioned above you will have droplets you want a mist . Your hand speed will also play a factor here .if your too slow ,you will have material bunch up if your too fast you will be thin. It is important to play with this until you are comfortable . Basically it’s a dance between air flow,material flow and hand speed . Water and food coloring is cheap way to get comfortable. Also I almost forgot to mention when spraying water Bourne finishes . You must must must clean it out of you gun totally . When that stuff curses your screwed. It’s not a solvent and will not come off . Hope this was helpfull
Jm

-- Smile and wave boys just smile and wave

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com