10 Waterborne Tech Tips

General Waterborne Finishing System Comments and Tips

1.  Water is unique and does not behave like conventional solvents. This implies that there will be an adjustment period required to “come up to speed.” Patience and practice will help achieve the full benefit of waterborne wood coatings.  Although, in general, the same equipment can be used to apply the waterborne wood coatings, there are a few tips that will help:

  1. Use stainless steel or suitable non-corrosive material for any wet parts of the spray line or coating application equipment used
  2. Spray tips, tip pressure, and pot pressure will require adjustment to provide optimum performance and may not be the same as that used with other coatings used in the past. For start-up we recommend the following:
  • With a HVLP gun we suggest using a fluid tip and needle size of 0.035” – 0.055” and air pressure of 40-55 psi to the gun. Use a pressure pot of 9-12 psi to pressurize fluid.
  • With conventional spray equipment, use a fluid tip and needle size of 0.035” 0.055” and air pressure of 50 to 60 psi. Again, a pressure pot of 9-12 psi is adequate to pressurize fluid.
  • For airless and air assisted airless systems, use a fluid tip and needle size of 0.009” – 0.015”. For airless spray use pressure of 1000-1500 psi and for air assisted use 400 to 750 psi.

2.   Grain Raise: YES – water raises wood grain, but can be made minimal and, when using our waterborne wood coatings, grain raise can be eliminated.  It is the strategy of the system to let the stains and sealers raise wood grain. In doing so, the sealer will “lock in place” raised fibers so that during the sanding process, a highly smooth, uniform surface is ready for topcoat application. After top coating, no secondary grain raise is seen and a high quality finish results. Best finish results are obtained by practice and patience and it will be found that the system is simple, easy, and remarkably fast!

3.  Waste Disposal: Check with your local sanitary treatment facility. They will evaluate materials for you in their effort to help you properly dispose of waste. Do not discharge any waste to a septic system or storm water drain regardless of how harmless you believe it to be! The EPA considers septic disposal as an underground injection and closely regulates discharges. Storm water drainage is also closely regulated. In the dry form, after water evaporation, the waste from ourwaterborne wood coatings is not regulated and may be disposed of as normal solid waste.  As a liquid it is quite common to find that SPDI waterborne wood coating waste material may be easily processed through municipal sewage treatment facilities – BUT CHECK FIRST!

4.  Topcoats may be used as sealers. The cost will be slightly higher and there may be less of a “fill” effect, but the final clarity is usually better.  This allows for increased production and up time and thus products pay for themselves by eliminating 1 current step with less wasted material.  It is recommended to first try the sealer and then evaluate the use of a “topcoat” sealer if higher clarity is still required.

5.  Coating Application: All of the waterborne wood coating products have been designed to coat uniformly over most wood species even when using standard tack cloths. Machine oils and other surface contaminants can interfere with coating application, so take care to prevent possible contact with these materials.

6. It has been observed, especially in spray lines, that the SPDI waterborne wood coatings actually may remove residues of other types of coatings. During start-up, it may be possible to observe “chunks”, “slugs”, and other particulate deposits on the surface after drying. These are most likely to originate from residues in the fluid lines or tips from prior coatings used. The following procedure is recommended for switching from solvent to waterborne

  1. First, empty solvent coating from system.
  2. Second, flush system with your cleaning solution.
  3. Next, flush system with IPA (isopropyl alcohol), or acetone.
  4. Then flush system with water.
  5. Finally, charge system with the waterborne coating.
  6. To go back to a solvent simply reverse the order.

7. Sanding: This is a critical step in finishing with waterborne wood coatings.  The higher the grit used in pre-sanding, the better the smoothness of the final finish. It is advised to pre-sand up to a minimum of 150 grit and it is preferred to reach 220 grit.  Apply primer or stain and sealer, and re-sand to 220 grit when completely dry.  It is recommended to always sand with the wood grain and, if using hand power sanders, to use a random orbit sander.

  • The application of one topcoat will be remarkably smooth and for many instances it will be sufficient as the final finish.
  • A second application of topcoat, after light fine sanding, will further improve final finish quality.

8. Drying & Curing:  Unless intended for forced IR or hot air drying, most SPDI waterborne wood coatings have been designed for ambient drying.  It is usually seen that it is dry to touch and sandable with in 10-25 minutes due to a very high content of solids and application of mil thickness.  Full dryness occurs within 45 minutes to 1 hour unless otherwise noted on Technical Data Sheet.

  1. Please take note that higher temperatures and air movement will speed drying even in high humidity.
  2. For best performance, if possible, maintain temperatures between 70°F – 100° F with humidity below 65%.
  3. IR heated or forced hot air dryers and other process drying equipment may be used to accelerate the drying and cure of these coatings.  Success will depend on the individual set of conditions determined by the finishing personnel.

9. Clean-Up:  Always flush the coating equipment and spray lines with clean water immediately after use!  The SPDI waterborne coatings are specifically designed to be very durable and chemically resistant.  Therefore, surfaces will be very difficult to clean if the coating residues are allowed to dry.  In the event that certain surfaces are covered with dried coating, it is recommended that MEK (methyl ethyl ketane) be used to clean the surface. Remember- SAFETY FIRST when using any cleaning solvent use appropriate precautions and disposal procedures.

10.Storage: KEEP FROM FREEZING! It is recommended to store all SPDI waterborne wood coatings at temperatures above 50° F and below 100° F.

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