Furniture Finishing, Spray Finishing With Lacquer

Spray Finishing with Lacquer

At the turn of the 20th century, as mass production of furniture grew, the demand increased for finishes that were quick and easy to apply, hard wearing and maintenance free. As a result, a whole new industry evolved, devoted to simulating traditional finishes. The scope and range of modern finishes is wide and varied, but we will focus on the most time tested, popular and simple to apply....lacquer. Standard Nitrocellulose lacquer is a fairly forgiving and simple finish to apply. Pre catalyzed and post catalyzed lacquers offer more protection, but the trade off is that for the beginner they are a little more difficult to work with.

Lacquer is the main finish we use in our refinishing shop, accounting for 90% of our finishes. Many of the refinishing episodes you will view on this site will be finished in lacquer.

Sealing the wood:

Most woods will need to be sealed before finishing. Surface preparation is very important. Stains must be allowed to dry completely before sealing. For sealing, you can use either lacquer sealer, vinyl sealer or shellac sealer. When using shellac sealer, it's important that the shellac dries for 24 hours before applying any lacquer over it.

Nitrocellulose Lacquer:

Nitrocellulose lacquer is the simplest to spray. It's normally always ready to spray right out of the can without thinning. If thinning is needed, lacquer thinner is what's used. After sealing is completed and allowed to dry, scuff sand lightly using 320 silicone carbide sandpaper. After denibbing the surface, spray your first coat of lacquer, applying a very light coat at first. This light coat will dry quickly, allowing you to follow up with a couple more light coats every half hour. After 3 or 4 light coats have been sprayed on, you can lightly sand with a scotch brite pad or 320 sandpaper, being careful not to cut through the finishes on the edges. You should now be ready to apply a wet coat, being careful not to spray any areas to heavily as to create runs. Runs do happen, as I can attest to even after 25+ years of spraying finishes. When you get a run in the finish, it's best to leave it go until the finish dries. Then, scrape the run carefully with the flat edge of a razor blade, slowly shaving down the run. Lightly scuff & respray as needed.

Blushing:

Blushing occurs when moisture in the air becomes trapped in the finish, causing a white foggy haze. To avoid blushing, avoid humidity over 65% when spraying. I find spraying very early in the morning is the best time of the day to avoid blushing in high humidity conditions. The other option is to add lacquer retarder to you lacquer to slow down the drying process. No blush is a product you can purchase through Mohawk that eliminates blush that has occurred in your finish. When you notice your finish has blushed...DON'T SPRAY AGAIN until the blush is removed! If you do, you will lock in the blush and it can no longer be removed.

How to apply the finish with a spray gun:

Left photo is the correct method: Always keep the spray path parallel with the work piece.

Right photo is incorrect method: swinging the gun produces uneven coverage of the piece.

Correct Incorrect

Applying the spray:

Overlap each stroke by 50 percent and spray past the end of the piece.

Aiming the spray gun:

When spraying a curved chair leg, spray directly at the center of the leg, using long upward and downward stroked. When spaying a square leg, aim at the corners of the piece using long up and down strokes.

Adjusting the spray gun:

Adjust the needle to alter the flow of the material out of the gun. Turn the lower needle knob in and less spray will come out of the gun. Crank it out and more fluid will be sprayed. Test to find the spray that best works for you. For what it's worth, I always crank mine all the way out.

The upper knob is the fan adjustment. Turned in the spray pattern will be tight. Cranked out the spray fan will be very wide. Again, practice to find what works best for you.

Spraying a Table:

When you are spraying, there will always be some overspray. Most will be sucked out by the exhaust system, but some material is bound to land upon areas already finished. A constant flow of material is vital and you must always keep moving the gun. Always spray with the trigger full on. On a table, spray the legs first, apron second, and finish with the top. You must move at a steady, but fast pace on a table, and focus very hard on watching your spray pattern making sure you overlap the last pass by 50%.

Spraying a Chair:

When spraying a chair, start with the legs first. Spray the inside of the legs, than the outside. Spray the rails in the same manner. Next, spray the outside back, then the inside back. Lastly, spray the seat. Since lacquer dries so fast, it's important to move fast spraying a chair, or you will be left with overspray to deal with, and some rough surfaces.