Here it is... A customer of ours has a 9,000 square foot house (yes, I said 9,000), and all of the woodwork in the house is a classic oak with a golden oak stain. She wants to change all of it to a mahogany/Cordova color. Large wall panels in study, molding, doors, base boards, window jams, kitchen - you get the idea. We normally would use transtints mixed in pre-cat lacquer to achieve the desired color and spray it with the HVLP, but we are worried about fumes and health issues being around that much spraying for 40-50 days. How do we tone using a water based product? What are the best products out there and should we HVLP spray it or is there some water based product that can be brushed? Also, what about water based glazes for this situation? We are not stripping the oak color, but scuffing the existing top coat and going over it. This is a huge job, so all your expert advice will help us through. We are in Scottsdale, Arizona.
From contributor R:
Just a thought - I have used shellac tinted with an alcohol based dye before. Works great and can be brushed. Just because you are using WB doesn't mean it's any safer. These products are hazardous also, and respirators, etc. are required.
How do you fit the frame to the flexible duct? Use plastic garbage bag with the bottom slit open (so that now you have a tube made of plastic sheeting instead of the original bag). And use aluminum foil tape to attach the garbage bag end to the flame and then the same type of tape to attach the other end of the bag to the flexible hose. For the exhaust, use the same garbage bag/flexible hose method to snake your fumes and overspray out an exterior window or door, away from the house.
Most or all of the overspray will be caught up in your hose system, creating a situation of a powdery mess when you need to move around or disassemble your components. The fumes will be blown through the flexible duct outdoors.
The suggestion to use shellac is excellent. The smell of shellac with its alcohol solvent is much more pleasing and even acceptable to customers than would be a coating using lacquer thinner. Shellac is known for its excellent ability to adhere, so a light scuff and wipe is all that's needed to get your intercoat adhesion. The shellac must go on in thin coats of spraying (unless you brush, which I suggest that you don't). Using strong concentrations of dye in the shellac does not kick the shellac out of solution the way that doing the same in lacquer (or precat) might without also beefing up the lacquer with acetone.
The reason that brushing on a colored coating is not the way to go is that unless your colored coating is opaque, you would be creating color streaks (uneven coloring). The only way it could work is if you want to spend way too much time brushing on multiple coats of lightly tinted colored material, building the color only a little at a time. There's just not enough consistency in the thickness of a brushed coat for this method to work effectively or in a cost-advantageous way. Spraying is essential.
I use a blend of topcoats/sealers/glazes and equipment from Target Coatings, Fuhr, General Finishes, Golden Paints and equipment from SATA and Kremlin. Basically the wide range of new finishes from manufacturers like Target allows me to create the same look as solvent without blowing the house or boat off its foundation or ways. Look at the new WB shellacs, sealers and topcoats from Target Coatings, glazes from Golden Paints and dyes from Homestead Finishing Products. Google these names and you will find excellent web sites.
Without getting critical about WB vs. solvent - the new WB's are looking very good. The learning curve is becoming shorter and the over effect is identical to solvent in 90% of all applications. Solvent still holds a small percentage of positives in a smaller realm of applications, i.e. high-build/glossy/eurotrash eye candy, but WB's will do just as well if not better in satin/flat applications for basic architectural use - without knocking the house down.
Depending on the job at hand, I use dewaxed shellac or a thinned WB acrylic lacquer as my intermediate color binder between the ground (base) color and my topcoats - no different then using shellac or nitro in a solvent application. The important part is understanding the dry time and schedules of these new products. They are quick but different. WB's can look butt ugly off of the gun, then level to a great finish when settled into the grain and substrate. Be patient!