Finish Choices for the High School Shop
What finish is advisable for instructional purposes in a high school? April 17, 2009
I am a wood shop teacher in western, PA and looking for an easy but professional looking finishing technique. For my own projects I use a lacquer process, but the school shop is not equipped for the smell of lacquer. Currently I have the students using polyurethane, but I have not been happy with the results. Any help/suggestions will be appreciated.
From contributor R:
I think shellac would be a good choice. There are many different applications to teach, they can make their own from flakes and even all the way to French polish for those really interested. Also WB finishes would be a good choice. WD Lockwood aniline dyes dissolve in water and can be sprayed or wiped. They are also non-toxic.
From contributor C:
Polyurethane makes a great finish but it can be a bit tricky to apply in standard formulations. The wipe-on polyurethane formulations are extremely easy to do a nice job with so they might be a good choice for you. They minimize the need for between-coat sanding and lap marks, drips, and sags are very much reduced in number and severity, even for inexperienced users. You can make your own wiping formulation from regular polyurethane by thinning it with mineral spirits. Thinned to about a 1:1 mix with the poly is about right. You can fine tune it a bit if you want faster build (less mineral spirits) or quicker drying (naptha instead of mineral spirits).
This is as close to a foolproof system as I have ever found. It takes more coats to get the same build as regular polyurethane out of the can but the applications dry quicker and take much less time per coat (even overall the timeline is extended a bit this way but the total finish time is usually less). If you'd rather buy it ready off the shelf there are wiping formulations sold that way too (Minwax for one example).
From Paul Snyder, forum technical advisor:
For easy to use and get great results I also like the wipe on varnishes. Minwax, Zar, General Finishes, Waterlox, and others all have good products to choose from. The type of stain I'd recommend for beginners depends on the type of wood they're working with. Oak, ash, mahogany, and walnut all take stains well and you can use Minwax, Zar, or a similar brand with excellent results. For aspen, birch, cherry, pine and similar woods that don't absorb stain evenly I'd go with a thick gel stain like Bartleys.
From the original questioner:
For this school year, I think I will try thinning the poly, but I am going to start experimenting with the water based finishes. Does anyone know of a good supplier on the eastern side of the country?
From contributor W:
For water based finish try the USL from Target Coatings. It is a water based lacquer and makes a beautiful sprayed finish. If you are spraying, you will still need a spray booth and respirator. It won't need to be explosion proof though - just a fan and filter. You could build one in the shop.
From contributor R:
For high school students I think it will be important for them to understand WB coatings as they are probably the finish of the future. Mohawk also makes a wipe on WB polyurethane called finish-up.