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Shellac: The Perfect Finish for Wood Shops. My Quest to Find the Perfect Finish for Student Use. Darin Petzold Serrano Intermediate Woods Saddleback Valley USD. My Requirements.
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Shellac:The Perfect Finish for Wood Shops My Quest to Find the Perfect Finish for Student Use Darin Petzold Serrano Intermediate Woods Saddleback Valley USD
My Requirements When you are dealing with multiple classes of 30+ students, the process of finishing becomes a HUGE undertaking. Here are my requirements when choosing a finish: • Easy to apply • Easy to clean up equipment and spills • Fast drying • Non toxic
My Requirements:Easy to Apply This goes without saying, if the finish is not easy to apply, it will be frustrating for both the students, and the instructor. If students do not see success, they will be less likely to put the effort into achieving a quality finish, so the learning curve needs to be fairly “flat” at least for the initial attempts at using a finish.
My Requirements:Easy to Clean Up Let’s face it…this is the instructor’s requirement! Ease of clean up is not only cleaning of the equipment, but ease of putting procedures in place for the clean up process. If the clean up of a finish product requires a lot of steps, the likelihood of students successfully completing the process is very low.
My Requirements:Fast Drying Unless you have massive amounts of space in your shop, storage of student projects is always an issue, especially when it comes to storing projects that need to dry. A fast drying finish will help solve this problem by allowing students to put their drying projects in their normal storage area by the end of the regular working period.
My Requirements:Non Toxic Many traditional finishes are soon to disappear due to recent rulings on the toxicity and volatility of the finishes. Water based finishes are the obvious solution to this growing problem. Though shellac is not water based (it is typically dissolved in denatured alcohol), it is FDA approved in it’s dried form. This also solves the problem of using a finish on items that are potentially toxic around children.
The Perfect Finish? I was reading a recent article in Fine Woodworking (December 2010 #215) that detailed the manufacture and history of shellac. As I read, I realized shellac would be the “ideal” finish I had been seeking. Here is a video supplement to that article. Origins and Manufacture of Shellac An email to the author, Vijay Velji proved worth the effort as he invited myself and three others down to his home workshop for a private workshop on shellac use and the French Polishing procedure.
Shellac: A Natural Product Shellac is secreted onto a branch by insects smaller than a grain of rice. It takes a tremendous number of these insects to create a pound of useable shellac
The Perfect Finish? We carpooled down to Mr. Velji’s house and were warmly greeted. He soon impressed us with his vast knowledge of shellac, his command of the French Polishing process, and his ability to describe the chemical processes that were in action. Our goal for the day was to ask many questions regarding shellac as a finish, and to have Mr. Velji guide us through the French Polishing process on a practice piece of Mahogony.
Our Day of Fun Tom Williams (Laguna Hills HS) and Mark Mora (Serrano Intermediate) are readying a squeeze bottle of denatured alcohol for use during the French Polishing process.
French Polishing Here is a short introduction to the French Polishing process. One of the many uses for shellac, and perhaps one of the most revered. Introductory Video on the French Polishing Process
French Polishing:Surface Preparation As with most finishing processes, surface preparation is the all important first step. Your finished product will only be as good as the prepared surface. Planing, scraping, and sanding are all good ways to prepare the surface.
French Polishing:Pore Filling When using an open grain wood such as Mahogany, pore filling is an important step in preparing the surface to accept the final finish product. In this case, very fine pumice is forced into the surface grain in order to fill the large crevices. The pumice will not only fill the gaps, but it will absorb the color of the shellac and blend in perfectly. An added bonus is that the process of forcing in the pumice will also finely sand the surface as well.
French Polishing:Bodying Bodying is the process of applying hundreds of very fine layers of shellac to the surface. Technique is critical in this step, but easy to learn. The key to this step is not to be in a rush, and to realize it is the fine layers that will eventually lead to the ability of the final mirror finish. Throughout this process, there is a wonderful opportunity to tie the concepts of refraction and reflection into the discussion! Bodying will take anywhere from a day to several days to complete.
French Polishing:Burnishing This step ties it all together and brings out the mirror finish. Students were seeing hints of what the finish would become during the bodying process, but it is the burnishing process that will really drive home the importance of quality work and attention to detail. Burnishing is the process of stretching and polishing the uppermost layers of shellac into a very fine and flat mirror-like surface.
French Polishing:The Finished Product The pictures tell the story! Though we didn’t go through the full bodying process, we were still able to produce a pretty fine finish. Left to right: Mark Mora (Serrano Intermediate head custodian, Robert Sherlock (Serrano Intermediate Assistant Principal, Tom Williams (Laguna Hills HS), and myself, Darin Petzold (Serrano Intermediate Woods)
Final Thoughts Shellac is definitely a finish worth exploring. I currently use it as a brush on finish for one of my introductory projects with my Woods 1 students. It is certainly not French Polishing, but it does add a nice finish to their wood. The beauty for me as an instructor is that it meets all of my requirements. I am looking forward to developing new projects that will allow my students the opportunity to go through the French Polishing process.
Final Thoughts Tom Williams (LHHS) was brave enough to put his woodshop kids to the task of French Polishing the shop benches! The sense of accomplishment those kids must have felt is priceless.
Final Thoughts I encourage you to visit Mr. Velji’s website. He sells a wide variety of shellac flakes and supplies. His DVD on the French Polishing process is highly rated and well worth the purchase. Shellacfinishes.biz