Instead of trying to control the temperature of your shop or the piece, why not just heat the finish?
You’re feeling really good today. Yesterday you almost finished the top coats and they went on great. You copy your mix and figure you’ll finish these last few items in short order, maybe even get a half-day ahead of schedule.
But it doesn’t work that way does it? It’s not laying out the same. There’s a hazy look or blushing to the finish. Maybe there are craters, dimples or air bubbles, or maybe it’s just not drying the same and you sand too soon creating a real mess to fix.
Every brand of finish has its own “specs,” which you’re instructed to follow. You call the help line, if there is one, and are told that there’s nothing wrong if you followed the steps correctly.
Earlier in my career this happened all the time. Things would go great some days and horrible the next. Yet I was following the instructions to the letter. I tried nitrocellulose lacquer, pre-catalyzed and conversion varnish, shellac, sealers, vinyl sealers — you name it — and could not achieve consistent results. So I decided to learn about the science behind the finish, figuring if I know the how, I can determine the why. I learned about the different solvents, fillers and ingredients that were used to make the finish and what each contributed. I found that temperature and humidity played a big role in how a finish went on and cured. Soon I began to experiment and had dozens of mixtures to cover most applications. Each one worked under the right conditions and I made notes of the temperature and humidity at the time I was spraying.
adjust the environment and controlling the finish with chemicals, I should adjust the temperature of the finish.
It was my “eureka” moment. Heat the finish, eliminate all the chemicals and you have a thinned product ready to spray!
The recipe (below) is simple: I add a catalyst and reducer to my clearcoat as prescribed for the brand used, then put the mixing container in hot water. If you want to be perfect you can heat the water to 78-80 degrees, but it doesn’t matter. I put it in hot water from the coffee pot, which gets the temperature to about 100 degrees, and the finish is thinned to half its starting viscosity in just a few minutes.
10, and the finish is always consistent. I can spray unless it’s raining and the humidity is 100 percent; then I just retard a little more and keep spraying.
It’s the simplest fix and seems to be one of the biggest secrets in the finishing world. I heat vinyl sealers, nitrocellulose lacquers, acrylics, pre- and post-cats, and any other finish that can be sprayed. I always add a little reducer for its flow enhancement capabilities. A heated finish will flash quicker and the reducer keeps it wet long enough for it to lie down and smooth out better.
My finishes don’t blush and always lay out the same. I don’t have to wait on the weather or pick the right mix for the conditions. I don’t need to stock extra chemicals and I don’t have to remember all those stupid formulas. I just put my finish in a container, heat it and shoot it. It’s that simple.
I’m no longer concerned with the humidity and temperature of the furniture or the finish. I’m back to spraying three or four coats, instead of the occasional
John Polgar is president of J.R. Polgar Inc., a professional restoration and refinishing shop in Clearwater, Fla.
Polgar’s basic spray mix
1. 15 ounces of conversion varnish
(varies with brand)
2. 1 ounce catalyst
3. Begin stirring CV, slowly add catalyst
4. Add 1 ounce of reducer, slowly stir-
ring it in
5. Place in hot water
6. Steep for 10-15 minutes 7. Stir and pour into gun 8. Spray!
(Note: Use common sense and avoid open flame or other unsafe heating practices.)
The 2007 Woodworking Industry Conference is scheduled for April 25-28, 2007, in St. Petersburg, Fla. The conference will focus on “Retooling America – Business practices to maximize your success,” offering tips and strategies for attendees to take advantage of the increased recognition among U.S. companies that retooling is the key to success.
WIC provides unique educational and networking opportunities, contact table sessions, and forums for sharing thoughts and ideas. Next year’s conference will feature a new Wood Product Manufacturer’s Forum that will allow participants to hear first-hand from wood products manufacturers about current issues facing them in the manufacturing process, technical innovations and their vision for what lies ahead in their particular markets.
The conference will also feature keynote speaker Howard Putnam, former CEO of Southwest Airlines.
WIC is open to all members and prospective members of the Association of Woodworking & Finishing Suppliers, Woodworking Machinery Industry Association, and Wood Machinery Manufacturers of America Association.
Contact: www.awfs.org, www. wmia.org, www.wmma.org.
I followed this practice for years with fairly consistent results but I wasn’t fixing the real underlying problem.
My finishing room was at least part of the problem. The spray booth — and I
use that term loosely — had an explo-sion-proof fan venting through the sidewall and air-conditioning filters that took “clean” air from the shop. The room was hot in the summer and freezing in the winter, despite my best efforts. I had some success acclimating the finish and furniture to the condition of the booth, and the recipe for that day’s finish often produced good results. But it was taking a long time to finish some jobs to the point where they were becoming losses.
Eventually, we gained a real spray booth with heating and cooling, a separate mixing room and curing area, and vent stacks through the roof. I was still following my mixing system and experiencing the same losses in time and material. Then a friend of mine, Greg Williams of Mohawk Finishing Products, suggested that instead of trying to
HELP RESTORE OUR BURNED FORESTS
Millions of acres damaged by wildfire urgently need native trees to prevent erosion and provide habitat for wildlife. These trees will purify our water, clean the air we breathe, and sequester climate-changing carbon dioxide for generations to come. You can help restore wildfire-damaged forest ecosystems through Wildfire ReLeaf. The USDA Forest Service matches every tree planted tree-for-tree, which means your $25 donation will plant 50 native trees in an area burned by destructive wildfire.
PLANT TREES ON-LINE AT
WWW.AMERICANFORESTS.ORG
OR CALL 1-800-545-TREE (8733) TODAY
Wildfire ReLeaf is a cooperative effort by
519-653-9322
Fax 519-653-3441 CDN Toll Free US Toll Free 800-265-0624 800-265-2759
357 Eagle Street North Cambridge, Ontario, Canada N3H 5M2
Fine Hardwood, Veneer and a
Commitment to Quality and Service
Since 1973
CUSTOM PROFILE
KNIVES
for ALL Moulders and Shapers
including Williams and Hussey
QUICK TURNAROUND
Axial Constant
CNC Generated Templates from $25 in One Day
Manufactured by:
221-B Cockeysville Rd.
Phone: (410) 771-0213
(800) 875-0213
e-mail: cayce@cayceco.com
Hunt Valley, MD 21030
Fax: (410) 771-0215
www.cayceco.com
References:
Archives