Hi Pete,

: I bought a HVLP gun from Harbor Freight on sale for about $50 a few months
: ago. So far, I've done two boats with it, using Epiphanes Hi-Gloss. To
: summarize my limited experience so far: Everything in the previous
: responses rings true with me as well. You can do it and get pretty good
: results early, but there is a learning curve involving: gun adjustments-
: there are 4 different things to adjust on my gun, and they all
: inter-relate. Find something to practice on to get your initial settings.

What are the 4 adjustments, fan width, fluid, air pressure at gun and air pressure at nozzle? These are the most common.

Air pressure at gun- this is the line pressure where the hose enters the gun. There should be a recommended setting from the manufacturer. This will vary depending on the diameter of the air line you are using. HVLP were originally designed to use a large I.D. hose with lower pressure but were later changed to use existing airlines. With a regular air line 40 pounds at the gun will probably be about right.

Air pressure at nozzle- this is the important one! Most HVLP use between 5 and 12 pounds at the nozzle. The reason the line pressure to the gun must be higher is to maintain the VOLUME of air to supply the tip. Automotive clearcoat is usually sprayed at 7-10 pounds at the nozzle. Varnish will be different but this number should come from the varnish manufacturer and you simply adjust it slightly to fit your spray technique.

Fluid- this is the amount of material you will apply when spraying. This is usually set by turning the adjuster until maximum flow is reached. When you are spraying you are using the maximum width of fan so the fluid setting is also at maximum. The only time you really change the fluid setting is when you change the fan pattern.

Fan width should be the widest you can get without the pattern breaking up. To get this, turn the nozzle 90 degrees so the pattern is horizontal. Aim the pattern at a piece of cardboard or paper taped flat on a wall. (Make sure that the gun is square to the wall in both the vertical and horizontal plane and is about 10 inches away.) Pull the trigger and allow the varnish to spray out until it runs down the wall. Adjust the fan until you have the varnish running evenly across the width of the fan pattern. Count the number of turns on the adjusting knob and make note of it so you can just set the gun to this each time you use it.

Now, you are set to spray. Adjust the speed of your pass so that you can see the varnish wet out at the back end of the pattern. (Don't adjust the gun settings to fit your spray technique. Adjust your technique, it is much easier.) Overlap your pattern by 50% on each pass. If you are having an orange peel problem it is probably because your not putting on enough material so slow your speed down a bit.

A couple of tips;

1-When you spray, get down at an angle to the surface and look at the texture in the light reflection. This is the best indicator of how well you are applying the finish.

2-Start spraying at the bottom and work up as this makes it easier to see because you don't have to look through the overspray to see the pattern edge.

3-HVLP guns are designed to spray HEAVY material so do not thin your varnish more than is recommended. This will cause poor performance and durability of the the varnish.

: I'd definately recommend getting a thinner for use in spraying, rather than
: the mineral spirits normally used in brushing. Get the same brand as the
: varnish, if possible. The downside of this is that personnal respiratory
: protection is a MUST, as the spray thinners are mostly that nasty ol'
: xylene.

Yes, use a respirator.

: For your spray booth, you can get the large rolls of the thin painters' drop
: cloth much cheaper than the clear visqueen we normally use for cheap
: tarping.

Put a fan in there somewhere to exhaust the fumes. Stick a furnace filter in front of your air inlet to trap dust.

: Spend the $7 for a Tyvek suit. You'll sweat like a pig, but I was surprised
: at the difference it made in comparison to wearing my regular overalls
: which apparantly shed like a cat. When done, hang the Tyvek suit inside
: out so it can dry quickly.

Yes, and only move around as much as necessary to spray. Movement raises dust. Also try watering the floor down before spraying to trap dust.

Ian