Spraying Waterlox finishes is possible using both a conventional or HVLP (high-volume, low-pressure) spray gun. HVLP is recommended due to less overspray and better transfer efficiency.
For both types of guns, based upon the solids and viscosity, the following thinning recommendations should be followed for spraying:
Waterlox ORIGINAL Sealer & Semi-Gloss Finish – no thinning required
Waterlox ORIGINAL Satin Finish – 10-15%
Waterlox ORIGINAL Gloss Finish – 10-15%
Waterlox MARINE Finishes – 25%
Waterlox URETHANE Finishes – 10-20%
We do not recommend spraying our UNIVERSAL Tung Oil, H2OLOX or TRUETONE products.
Only use mineral spirits or naphtha as thinning agents. Other types of thinners (e.g.: lacquer thinner, Toluol, xylene or acetone) will wrinkle the previous coat if used. Turpentine may be used; however, it will significantly increase the dry time and may cause running and/or sagging on vertical surfaces. Conversely, it will improve flow and leveling on horizontal surfaces.
Tip sizes vary between manufacturers and for the product being sprayed. Select the tip size according to the manufacturer’s recommendation for “thin, lower solids, non-pigmented type paints”. Some manufacturers list “varnish” as a selection; which would be suitable. Usually one of the smaller tip sizes will work best. Adjust air pressure, fan size and feed rates until the desired spray pattern is achieved.
Spraying any type of finishes or varnishes is an art form, just like using a brush or roller. Techniques are learned through experience and trial and error. We suggest experimenting first on either scrap wood or cardboard before starting the project.
A conventional gun should be held about 8-10″ away from the project surface and an HVLP gun 6-8″ away. Hold the gun off to the sides of the workpiece and depress the trigger. Move across the workpiece, laying down a swath of finish without arching your arm. The finish should not puddle as you spray. Release the trigger only after leaving the other end of the work surface. As you make the next stroke, overlap the first by half its width.
When spraying vertical surfaces, move the gun quickly enough to prevent sagging. With proper gun adjustments and spray technique the results should be a coat that appears smooth and does not feel rough when dry.
We suggest you apply your first pass on the dryer side, meaning do not try to lay down a thick wet coat on the first pass. Immediately come back with a wetter coat on your second pass and then with your third or fourth pass apply enough so the surface has a continuous wet film on top. This should be approximately 3-5 wet mils of varnish. Do not leave any “dry sprayed” or starved areas as these will not necessarily flow out properly. Do not try to build up too thick of a coat with fewer passes; rather apply multiple thinner coats until the surface is properly coated.
Unlike lacquers and some other types of coatings, varnishes do not re-melt the previous coat; therefore, you must apply a smooth and consistent film with each coat. After each coat has dried, apply your next coat in the same manner, building coats to the desired or prescribed film build for your project.
Sanding between coats is not necessary for adhesion; a light sanding with 320, 400 or 600 grit paper or 4/0 steel wool may be used to remove any debris or uneven imperfections between coats. If using our Waterlox VOC Compliant Tung Oil finishes, wait 24 hours to re-coat if sanding is performed.
Spraying vertical surfaces is much more difficult than horizontal surfaces. If possible, position the project horizontally.
Pour unused material back into the container, run mineral spirits through the gun until clear, break down gun and clean if desired.
If solvents other than mineral spirits are used to clean the gun, or if the gun is used with other finishes, run a small amount of mineral spirits through the gun prior to using Waterlox to clear out the other solvents.