Paint Spraying Guidelines - How to Spray KBS Coatings with an HVLP Spray Gun

Spraying KBS Coatings starts with the right setup: thin with KBS #1 Thinner only, open the fan to an 8 to 10 inch pattern, then hold the gun 6 to 8 inches from the surface at 90 degrees and overlap each stroke by 50 percent. Keep moisture out of the air line and clean the gun immediately after every use.

What You Need Before You Spray:

Spraying KBS Coatings takes four things: an HVLP spray gun, clean dry air, KBS #1 Thinner for reducing and cleanup, and a paint strainer. The KBS HVLP Spray Gun runs at 20 to 45 PSI with a 600cc cup and over 65 percent transfer efficiency, and ships with either a 1.4mm tip for basecoats and clears or a 1.8mm tip for primers and heavier coatings.

For small parts, touch-up work, and clear coats, the KBS HVLP Mini Spray Gun with its 1.0mm tip gives you finer control. It is a popular choice for spraying DiamondFinish Clear and KBS MAXX Clear.

Always strain your paint when pouring it into the cup. A strainer costs a few cents and a clogged tip costs you an afternoon.

Thinning KBS Paints for Spraying:

Reduce KBS paints with KBS #1 Thinner only. It is a slow evaporating, low VOC solvent made for RustSeal, DiamondFinish Clear, KBS MAXX, BlackTop, KBS Top Coater, Motor Coater, and the rest of the KBS line. Regular solvents may contain moisture that adversely affects how the coating performs.

How much to add depends on the product, so check that product's directions page before you mix. RustSeal usually sprays without thinning, and 5 to 10 percent is plenty when it does need help. DiamondFinish Clear takes 10 to 15 percent for spraying and can go as high as 30 percent. KBS MAXX and MAXX Clear come pre-thinned and are ready to spray as mixed.

Never reduce a KBS coating with lacquer thinner. It flashes off too fast, and any residue left in the gun will attack adhesion the next time you spray. After thinning and stirring, strain the paint through a 100 micron filter before it goes in the cup.

Keeping Moisture Out of Your Air Supply:

Moisture in the air line will ruin a KBS paint job, and a wall-mounted trap at the compressor does not stop it. Air cools as it travels, so condensation forms in the hose downstream of every filter you own and arrives at the gun as water. The fix is to filter at the gun itself, which is the last point before the paint.

The Dry Air Spray Gun Filter attaches directly to the air inlet of your spray gun. It absorbs up to one fluid ounce of moisture along with oil aerosols and contaminants down to 0.01 microns, and it does it at a true 30 CFM with almost no pressure drop. This disposable filter is the direct answer to fisheye.

Setting Up Your Spray Gun:

Set up an HVLP gun in five steps: attach the cup with strained, properly thinned paint, close both control knobs, set the regulator to the pressure your gun manufacturer specifies, back both knobs out to the first thread, then open the fan on a test panel until you get an 8 to 10 inch pattern with even wetness. Work through them in order and the gun is ready before you touch the part.

Step 1: Fill the Cup

Attach the cup to the gun and pour in your mixed paint through a strainer. Mix the KBS #1 Thinner with your chosen KBS paint first, at the ratio that product's directions call for.

Step 2: Close Both Knobs

Most guns have two control knobs. The upper one is the fan control and the lower one is the fluid control. Turn both fully closed to start from a known position.

Step 3: Set the Regulator

Connect the air and set the regulator to the pressure your gun manufacturer states. The KBS HVLP Spray Gun works at 20 to 45 PSI and uses 6 CFM at 43 PSI, so check that your compressor keeps up at that flow rate.

Step 4: Back Both Knobs Out to the First Thread

Open the fan control and the fluid control until the first thread just shows on each. Both are fully adjustable from there, but starting at the same place every time makes the next step repeatable.

Step 5: Dial It In on a Test Panel

Spray a piece of cardboard and open the fan knob counter clockwise until the pattern reaches 8 to 10 inches. Watch the wetness while you do it. Uneven, spotty, or dry looking coverage means you need more fluid, so open the fluid knob in full turns to get close and then fine tune. Go too far and the paint sprays too thick, which shows up as runs and sags.

Spray Gun Technique:

Good spray technique comes down to five things you control at once: gun distance, gun angle, overlap, gun speed, and trigger control. Hold the gun 6 to 8 inches out at 90 degrees to the surface, overlap each stroke by 50 percent, keep your speed constant, and fully depress the trigger on every pass. Perfecting the art takes years, but these five get you a good finish now.

Gun Distance

Hold a fast drying paint 6 to 8 inches from the surface, tip to surface. Most KBS paints are fast drying, so this is your working number. Slow drying products such as enamels want 8 to 10 inches. The hard part is holding that distance while you move side to side, which means sliding the whole arm rather than pivoting at the elbow, even though pivoting feels more natural.

Gun Angle

Keep the gun at 90 degrees to the surface through the entire stroke. That means the gun points straight at the panel without angling to either side. Your wrist wants to stay stiff, so bend it at the beginning and end of each stroke to hold the right angle. It feels awkward for the first few passes and then it becomes automatic.

Overlap

Overlap every stroke by 50 percent. If each pass lays down a 10 inch band, the next pass covers about 5 inches of it. Lining the top of the second stroke up with the bottom of the first is the common mistake, and it leaves hard edges and spotty coverage. Half-and-half coverage evens out the film and hides the edges.

Gun Speed

Gun speed is how fast you stroke back and forth, and there is no set number. Whatever feels comfortable works as long as it stays constant. Match the fluid knob to it: a slower, more even stroke wants less fluid, and a faster stroke wants more.

Trigger Control

Aim for a fully depressed trigger on every stroke, because that is what gives you a uniform amount of paint per pass. The trigger works in two stages. Squeezing partway starts the air, and pulling further engages the fluid up to whatever the fluid knob allows. Feathering means getting the air moving and bringing in the fluid just before the stroke reaches the edge of your work. If a full trigger pull puts down too much paint, turn the fluid knob down rather than short-pulling the trigger.

How to Fix Orange Peel When Spraying:

Orange peel is a bumpy, dimpled texture left when sprayed paint does not flow out level before it sets. The usual causes are thick paint, low air pressure, a gun held too far away, or a thinner that flashes too fast. Fix the setup on a test panel, then sand and buff the part or recoat it.

What Causes Orange Peel

Orange peel comes from how the paint is thinned, how the gun is set, or how warm the work area is. Check each cause below against your own setup.

HVLP Settings by Product

Match the thinning, air pressure and tip to the product you are spraying. These HVLP starting points come from each product's directions page.

Treat these as starting points. Your gun and compressor may need a different setup, so confirm it on a test panel before you spray the part.

Stop Orange Peel Before the Next Coat

Work through these on a test panel, in order, before the gun goes back on the part.

1. Thin the paint within its range with KBS #1 Thinner, stir it, and strain it through a 100 micron filter.
2. Set the regulator to the air pressure listed for that product.
3. Spray the test panel from 6 to 8 inches with an 8 to 10 inch fan.
4. Open the fluid knob until each pass looks evenly wet. If the paint runs or sags, back the fluid down.
5. Change one setting at a time so you can see which one cleared the texture.

Fixing Orange Peel in a Dried Coat

Orange peel can be corrected once the coat has cured. Sand the texture level, then buff the gloss back or spray another coat.

KBS exterior topcoats can be wet sanded and buffed. That covers DiamondFinish Clear, KBS MAXX Clear, BlackTop, KBS MAXX and KBS Top Coater. Motor Coater can be sanded and buffed too. Dry sanding and buffing works as well. Use 1000 to 3000 grit paper, picked by the size of the imperfections: heavier texture needs a coarser grit to start, and light texture may only need the fine end of the range. Finish with rubbing compound and polish.

Let the coat cure before you sand it. The wait depends on the coating.

Satin and flat finishes: sanding and buffing can change the sheen. Test a small area first. If the sheen has to match, sand the texture level and spray one more coat instead of buffing.

RustSeal can be sanded smooth as well. Sand the texture level, then spray another coat with the corrected setup or apply your topcoat. The RustSeal directions call for a 320 grit scuff once a coat has cured for 24 hours.

Motor Coater has its own recoat timing. It takes a second coat within 30 minutes or after 7 days, so if you plan to recoat it, wait the full 7 days before you sand.

For heavy texture on any coating, sand the surface level and respray instead of trying to buff it out. Follow the recoat window and scuff grit in that product's directions.

Troubleshooting Other Spray Defects:

Most other spray defects on KBS Coatings come from four causes: coats sprayed too heavy, the wrong recoat timing, a contaminated surface, or paint that was not fully mixed. Find the defect in the table below, correct the cause on a test panel, then repair the part.

Bubbles, Pinholes and Solvent Pop

Bubbles form when the surface of a coat skins over before the gas underneath has escaped. RustSeal, BlackTop and DiamondFinish Clear are moisture cured and release gas as they cure. A heavy coat, a recoat applied too soon, or high heat and humidity traps that gas under the skin.

To prevent bubbles:

• Spray thin covering coats. Two thin coats are better than one heavy coat.
• Recoat only when the last coat is dry to the touch and leaves no fingerprint. That is typically 2 to 6 hours for RustSeal and 2 to 4 hours for DiamondFinish Clear.
• Spray in moderate to dry conditions, inside the product's temperature range. Do not spray in rain or high humidity, or onto a damp surface.
• Stir the paint. Do not shake or whip it, which adds air bubbles.
• In high heat or humidity, thin DiamondFinish Clear more than normal, up to 30 percent, to avoid micro-bubbling.

To fix bubbles, let the coat cure until it sands without gumming the paper. Sand the bubbles smooth, scuff with the grit in that product's directions, clean and dry the surface, then spray another thin coat. If the bubbles run through several coats, sand back to a sound layer first.

Runs and Sags

Runs and sags mean too much paint landed in one place. The coat went on too heavy, the gun was too close, or the pass was too slow.

To prevent runs:

• Turn the fluid knob down. Do not short-pull the trigger to cut the flow.
• Hold the gun 6 to 8 inches from the surface and keep your gun speed constant.
• Build the finish in thin coats, and let each coat dry to the touch before the next.
• Let the paint and the part reach room temperature before you spray.

To fix a run, let the coat cure for the wait time listed in the orange peel section. Sand the run level, starting with 300 grit. From there, either spray one more thin coat, or work up through 1000 to 3000 grit and buff.

Fisheyes and Craters

Fisheyes are small round craters that open in the wet paint right after it is sprayed. They come from contamination on the surface or in the air supply: oil, grease, wax, silicone, a fingerprint, or water and oil from the air line.

To prevent fisheyes:

• Clean the surface with KBS Klean, rinse it, and let it dry completely.
• Avoid solvent-based cleaners, solvent wipes and tack cloths. They leave a residue.
• Handle the cleaned part with gloves so you do not leave oily fingerprints.
• Filter the air at the gun with the Dry Air Spray Gun Filter.
• Do not spray over a surface that has had wax, polish or silicone on it until it has been cleaned.

To fix fisheyes, let the coat cure and sand the craters smooth. Clean the surface again with KBS Klean, let it dry, then respray.

Do not add fisheye eliminator to KBS coatings. KBS does not recommend these additives, because they can create other problems with our paints.

Cleaning Your Spray Gun:

Clean the gun with KBS #1 Thinner immediately after every use, before the paint has any chance to harden. Nothing clogs moving parts like cured paint, and a gun that was put away dirty shows up in the next finish. Never use lacquer thinner, since the residue it leaves behind will prevent good adhesion the next time you spray.

Disconnect and Drain

Disconnect the air hose first. That is a safety step and it also keeps you from spraying paint into your own face. Take the cup off and let whatever is in the pick-up tube drain back into it, then dispose of the leftover paint properly.

Never pour used paint back into the can. RustSeal is a moisture cured urethane, so paint that has been exposed to air has already started curing. Returning it to the can starts the same reaction in what is left.

Flush the Gun

Wipe the cup out with KBS #1 Thinner and a clean rag. Fill it halfway with thinner, reconnect the air hose, and spray it through to flush the fluid passages. Then unscrew the air cap, the piece that threads over the tip, and soak it in clean solvent until the material loosens and flows out.

If you have to force a hole clean, use something soft like a tooth pick. Anything hard, like a metal pick, can enlarge the holes and wreck the spray pattern.

Lubricate Four Points

Finish by lubricating with a non-silicone, non-petroleum spray gun lube. Three points take the lube: the air valve packing, the fluid needle packing, and the trigger bearing screw. The fourth point, the fluid needle spring, gets petroleum jelly instead and sits inside the gun behind the fluid adjustment knob. Follow your gun manufacturer's instructions to disassemble and reassemble for access.

Spray Settings Reference:

Frequently Asked Questions: Spraying KBS Coatings