FAQ for HVLP spraying guns

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Are HVLP Turbine Spray guns easy to use?

HVLP sprayguns are easier to use than most sprayguns (especially when compared to high pressure sprayguns). This is because the pressure is low resulting in a softer spray pattern. Turbine sprayguns also operate with much less pressure (at the sprayhead) than the compressor HVLP sprayguns (conversion type). So you can expect even less overspray and bounceback with a turbine spraygun. Even for a novice, it takes very little practice to spray and achieve professional results with a turbine spraygun - thanks to the lower velocity. If you can use a paintbrush, you can spray with HVLP.

Should the turbine case be hot?

Yes, the turbine motor heats up within a very short time and the air becomes hot - especially at the turbine. In fact, if you let the turbine run for 15 minutes or so you had better be careful removing the hose from the turbine. The brass connector will be too hot to touch. The heat is from the copper motor windings and the bearings - remember, these motors are operating at 19,000 - 21,000 rpm. Plus, our bleed-off is inside the case so this hot air soon heats up the metal case.

Where should I place the Turbine?

The best place is on the floor at least 20ft away from the spray area. Any 3 or 4-stage turbine should last 10 years or more of normal use (3 - 4 times a week for a few hours at a time). For occasional use it will last much longer. However, there are certain conditions that can cause premature burnout with any turbine.

1) Do not place the turbine up high off the floor.

The turbine is better placed on the floor. The reason for this is that it allows the hose to come straight out from the turbine and the air to flow unrestricted. If the turbine is up high, the hose bends down towards the floor causing some back-pressure at the bend. Even with high pressure this type of thing is a cause for pressure loss, but it is even more important with very low pressures. You may get 6psi out but 1 psi back. The motor will overwork and overheat.

Another reason for not placing the turbine up high is that where the hose reaches the floor it will bend and flatten (due to the weight of the hose). This may cause some restriction.

2) Do not place the turbine in a box.

This sounds like a great idea to reduce noise and keep the turbine away from shop dust. Unfortunately, our experience shows that the turbine will overheat. If the turbine case is covered, then the hot air released from the vents (from the cooling fan and bleeder in the manifold) will be re-circulated and drawn in through the filter and into the motor housing. This pre-heated air will cause overheating and prematurely damage the motor. The Fuji turbines are sealed to the outside air. This design ensures that only ambient air can enter the turbine. But placing the turbine in a box circumvents this design - please do not do it.

3) Do not place the turbine in the next room - unless...

This sounds pretty innocuous and sometimes is. If it's in the next room it's away from fumes, overspray and the noise level is less etc. But if the hose is passing through a hole in the wall traveling over a baseboard, where the hose sits on the bottom of that hole it will flatten out and cause blowback into the motor. The result will be overheating. So if you intend to do this, at least bore the hole through the wall at ground level or have the Bend Restrictor portion of the hose poking through the wall to prevent flattening. Another way is to use a metal conduit going through the wall and attach the standard hose to this conduit in the spray room and attach a shorter hose from the turbine to the conduit in the other room.

Another reason why the 'next room' is sometimes not a good idea is that we have heard from some end users that they don't turn off the turbine at all because it's 'out of sight, out of mind'. Well, it's best to remember that the 'turbine', from any HVLP maker, is simply a high-powered vacuum cleaner. It's not good to leave any vacuum cleaner on for hours when it's not in use.

A better idea may be to install a wireless switch so that the turbine can be turned on and off remotely (when filling the can with paint for instance).

Size of Turbine Case - Does it matter?

The smaller the turbine case, the easier it is to cool. What you need to know is that what HVLP makers call the turbine 'motor' is actually a bypass vacuum motor. This unit has fans (called 'stages') at one end and its own small cooling fan at the other. In between the stages and the cooling fan are the copper windings necessary to power the motor. It is these copper windings that must be constantly cooled.

The cooling fan is not much different from the type of fan seen in computers except that this fan is secured to the same shaft (rotor) as the main stages (fans). What this means is that all fans, including this small cooling fan, rotate at 19,000-21,000rpm (depending on the motor and certain conditions).

So as you know, it's much easier to keep a small room cool with a window air conditioner than it is to keep a large room cool with the same air conditioner. It is the same situation with turbine case size. The cooling fan size and speed is preset, so a smaller case will be easier to keep cool.

The cooling fan air escapes through the vents in the case.

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Why is there 'Paint' Buildup at the vents?

Because the air passing out through the vents is hot, you can expect to see dried paint particles (or whatever you are spraying) on or around these vents. This is normal with any turbine. Although overspray is greatly reduced, there is always some in the air and this overspray simply lands on the turbine and at the vents where it is instantly blow-dried by the hot air. This buildup is not paint particles passing through the turbine filters and being vented out.

Can Brushing be compared to Spraying?

In order to spray intelligently, it's helpful to know just how similar spraying is to brushing - in fact, at Fuji, we often say that a spraygun is simply a paint brush with no bristles.

Similarities:

BRUSH: Paint is liquid in the can and applied with a brush to form a liquid layer on the substrate (any object such as a board).
SPRAY: Same, but spraygun aircap atomizes (converts) liquid to small particles.

BRUSH: Paint is applied full-strength.
SPRAY: Paint must be thinned.

BRUSH: You instantly begin moving with the brush as you begin to make a pass across the board.
SPRAY: You start to make the pass and pull the trigger just before the edge of the board.

BRUSH: After the brush passes off the edge you don't continue trying to paint in mid-air.
SPRAY: You let go of the trigger so that atomized paint particles cease being directed into the air (one of the two main causes of overspray - bounceback is the other).

BRUSH: You overlap passes with the brush to blend into and over a portion of the last pass.
SPRAY: You overlap about 1/3 to 1/2 over the previous pass to make the transition invisible.

BRUSH: When you dip the brush in the paint can you wipe off the brush to make sure you don't apply too much paint at one time. Excess causes runs and it also forces you to move too fast.
SPRAY: You adjust the Fluid Adjusting Knob (Rear of gun) to reduce the paint flow allowing you to move at a reasonable speed (for your skill level).

BRUSH: While making your pass with the paintbrush you do not move the brush in and out - you keep it the same distance away from the board the whole time.
SPRAY: Spraygun should be held same distance for the whole pass. Added info: The Aircap should not be held more than 8" away from the board but can be as close as you like (the shorter the distance, the smaller the size of the fan pattern and the more control you have).

BRUSH: The angle you hold the paintbrush should not change significantly while making a pass.
SPRAY: Generally speaking the spraygun is held at 90 degrees to the board throughout the pass. However, as long as the angle of the gun is kept the same, the gun can be held at a slight angle if necessary.

How far away should I hold the spray gun?

The Spray Pattern is fan-shaped, so for a larger sized fan you do not have much choice - you will be at or close to the maximum 8" distance. It's impossible to produce a large spray pattern if you hold the spraygun close to the object - there is no room for the fan pattern to expand.

As you move closer with the gun, the fan will become a smaller size. So for instance, what was 10" at a distance of 8" becomes about 2" fan at 2" distance.

When you want to paint something that is, let's say, 2" across and 6ft long - you will find it much easier if you move the gun closer. This will give you the ability to control your pass from side to side properly without wandering all over the place. Plus it will reduce overspray. Imagine spraying 1/2 chair spindles from 8" away with a spraygun when you don't have the bristles to help guide you - it's very difficult. So simply adjust the pattern to be smaller and cleaner and move in close until the fan is the exact same size at the spindles. Once you are close, you will be able to guide the spraygun easily and it will not be as important to have a completely steady hand.

Once again, liken it to painting with a brush. You would have no problem with an 8" wide brush painting a swath across a wall even though you were holding the end of the brush handle 8" away from the wall. But now imagine trying to paint a 1" line across the wall holding the end of the brush handle. It would be difficult not to paint wavy lines because each movement of the hand at the end of the handle would be amplified on the wall. But as mentioned previously, we do not have the benefit of bristles to help steady and guide our hand when we are spraying - so stay in nice and close.

As an aside - it is usually not possible to bring the sprayhead close to the object with other methods of spraying (high-pressure for instance). Doing so would produce too much bounceback. The pressure is so much less with turbine HVLP that this is not a problem.

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Is thinning necessary or important with HVLP?

Viscosity of coatings is important. Although we supply a guide, there is often some trial and error involved in arriving at the best viscosity. If a product is thinned too much, there are runs. Too thick and 'orange peel' or rough finish is the result. When thinning, it is essential to use a reducer that is compatible with the product you are using. To be sure, buy a thinner/solvent made by the same coatings company - always verify that it is the right product. It is wise to experiment on a practice piece to ensure that the finish is perfect. You may also request information from the coatings manufacturer - don't forget to mention you are spraying with HVLP equipment. Water-based lacquers (acrylics, urethanes and varathanes etc.) can be applied successfully with HVLP. Some of these products require no thinning whatsoever (but some do). Many of these newer coatings contain a high-solids content of 60% or more so the turbine must also be powerful enough to handle waterborne products. A 3-stage system is recommended is you want to spray waterbased/borne coatings. Several thin wet coats are preferable to one or two thick coats. Scuff sanding between coats is recommended. Most users report that the preferred Aircap Set for water-based (water-borne) coatings is the #3 Set - this is because these coatings are best applied in thin, wet coats (layers) to prevent orange-peel and bubbles in the finish.

Can I spray household trim with Latex Paint?

Yes, HVLP is ideal for this application but you must follow a few general rules in order to achieve a good finish. If you intend on spraying Latex Emulsion Paint (House Paint) most of the time, please consider purchasing the more powerful 4-stage turbine systems. To spray Latex paints successfully, some rules must be adhered to. The latex should be 'finish-quality' (the best grade). For best results, a Latex Additive such as Floetrol should be used (Call 1-800-321-3444 for your nearest dealer). Important* Floetrol is not for thinning - it is a product that prevents the paint from drying too quickly - in other words, it is a 'retarder' - it slows the drying process allowing the paint to level more smoothly. You still must thin with water. Thin the Latex with water - usually 20% is enough. The #4 Aircap Set is preferred for decent coverage on items like household trim, louver doors, fireplaces, cabinets etc. When spraying Latex, please turn the fluid adjusting screw to limit the paint to a finer spray. This will increase the ratio of air to paint and result in better atomization and a beautiful finish. (Factually speaking, it doesn't increase the ratio of air to paint but does the opposite - it allows the air atomizing power to work on less paint thereby improving the quality of atomization). Spray the paint on 'wet like a lake'. In other words, it must be completely wet in order to flow out nicely and look smooth. If you are only seeing droplets on the surface, open up the fluid knob for more product.HVLP is designed for fine-finishing, this includes... furniture, pianos, cabinets, automobiles, machinery - anywhere a 'Class A' coating is to be applied. If you already own airless equipment, you'll find that an HVLP system will complement it perfectly. Although there is some overlap, every family of spray systems on the market has its special place. For more information about spraying techniques, check out the books listed in the Recommended Reading Section.We have found that if you do all of the following, you can achieve a professional finish with Latex House Paint.

What is the Secret to spraying Latex Paints?

    1) Use the correct Aircap Set
    2) Thin the paint somewhere between 20% - 25% with water
    3) Add Floetrol Latex Conditioner to slow the drying
    4) Add the 6ft Whip Hose to reduce air temperature through the gun
    5) Hold the gun no more than 8" (20cm) away
    6) Apply a full, wet coat (wet like a lake)

Can I spray walls & ceilings with HVLP?

If your main purpose in buying a system is to paint walls with latex, then we want you to know that you will probably have to thin the paint. Some professionals do not want to do that, but really, it shouldn't deter you.Although HVLP turbine systems were not designed to spray walls/ceilings, thousands of people have used the Fuji System to paint walls with latex and they are very happy with the result. Just remember to use Floetrol and thin with water (about 20% - sometimes less). For walls you would need the #6 Aircap Set for greater coverage. The reason a turbine system is not 'ideal' for walls/ceilings is because you have to keep filling up the 1 quart (1000cc) cup. But our opinion is that it is still much faster than rolling because with the roller you constantly have to add paint to the roller - this takes a lot of time and you do it often. At least the cup does hold a full quart of paint and this goes a long way. Because you will be using a larger Aircap size (#6) you can expect some texture (though not as much as with a roller). Texture can be minimized by using Floetrol as well as thinning with water. A little texture on walls is totally acceptable.

I don't recommend it ... too much work ... HVLP spray guns are for small and delicate projects ...

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Can I spray Nitrocellulose Lacquer?

It’s the same answer as with any coating, 'yes... just so long as you thin it appropriately.' Spraying of lacquer may be prohibited in your location. Also, the amount of thinning may be controlled too. Please check with the local jurisdiction in your area before setting up. Lacquer fumes are toxic and flammable (combustible) so adequate ventilation is absolutely necessary. Explosion-proof light switches, fixture and extraction fan are a must.

Lacquers were formulated to dry extremely fast. The very fact that the turbine motors become hot and produce heated air can be counter-productive with lacquers. If you spray as you would with regular slow-drying paints, you may find that you can only spray a dry coat or you get orange-peel. But as always, there are ways around problems like this.

1) Make sure you are using the correct Aircap size (Standard Size).

2) Apply at least 2 coats of Lacquer Sanding Sealer first and sand flat. The Sanding Sealer sands nicely (unlike some lacquers) giving you a perfect base for the topcoats. Please note: Sanding Sealer will not fill in grain unless the grain is unbelievably fine. You should use Filler for grain (unless you want the grain to show).

3) Thin the lacquer until it levels out on its own (unless this contravenes local rules).

4) Add a Lacquer Retarder to slow the drying process (usually available from the same factory as the lacquer.

5) Add another hose (shorter) to the standard 25ft hose. This will result in the air passing through the aircap being 15 degrees cooler. Fuji also has an inexpensive 8ft length that can be used for this purpose at the turbine end (7011). Or you can choose to go with the more expensive 'Whip Hose' #2049F if you also want more flexibility and lighter weight.

6) Get in close with the gun and apply a wet coat - 'wet like a lake.'

If all of the above instructions are followed, then a beautiful finish will result. This assumes that the spraygun is held no more than 8" away from the surface being sprayed (closer is ok). We also assume is that the lacquer is thinned enough. In fact, if you have done all of the above and are still getting orange-peel, you will almost definitely have to thin more.

Always use lacquer, sanding sealer and thinner/solvent from the same company to ensure compatibility.

How can I reduce overspray?

Overspray can be reduced to an absolute minimum by doing the following...

a) Adjust the size/shape of the spray fan pattern to suit the object. This may mean moving the gun closer than the maximum 8". Thin objects such as spindles or railings can be sprayed with the round pattern and the gun held up close. Overspray is caused by the particles that 'miss' the object.

b) Thin only as much as necessary and no more. Experiment with less thinning. However, always remember, the paint must be thin enough to level out ON ITS OWN after being applied wet. Make a note of the thinning for next time.

c) Never hold the gun further than 8" away from the surface. Closer is better.

d) Reduce the air pressure/cfm at the Air Control Valve. Practice first on something not important rather than ruining your project. Once the point is reached where the finish starts to suffer, tweak the air control valve a little for more psi. The complete project can now be sprayed with the same setting for the air. Reducing the pressure is the best way to reduce bounceback and overspray to an absolute minimum. If the 'paint' is not sufficiently thinned, then you will not be able to reduce the air. The paint must level on its own.

e) Learn to trigger on and off accurately. Remember, as you come off an edge and continue to depress the trigger, hundreds of particles are being sprayed into the air. Eventually this will buildup 'mist' in the room. The Fuji High-Efficiency Aircaps reduce overspray significantly (installed in all our spray guns).

f) Use some type of extraction fan and spray close to it. You may need an explosion-proof fan depending on which product you are spraying - please check with the local jurisdiction.