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History of the Forest Products Laboratory

Interview #992: Lulling, Robert M. (June, 2009)

View all of First Interview Session (October 15, 2008), disc 1

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00:46:57 - 00:53:21 Southern Pines

Southern pines, projects, deforestation , wood---grading, Weyerhaeuser Company, wood---defects, resorcinol; Selbo, M.R., wooden fences, house construction---climatic factors, paints

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00:46:57

RL

Lots of poor grade Southern Pine forests are located in New Mexico and, of course, good wood was becoming very---in short supply. Industry was interested in trying to find ways of using up the wood that may not be, quality-wise, up to their grade. So we tried at the Lab here to improve the quality of the wood by various means, and one of those means was to---in plywood they made what they call ship patches and Weyerhaeuser actually perfected the method, which is automatically on a conveyor going by and it would stamp out defects---the defects were mostly where the branches were cut off and whatnot and they would leave a scar---then it would be made into plywood. Of course they used [resorcinol?] type glue which actually was formulated in Germany. When I told you about these guys going to Germany one of the things they found was this [resorcinol?] adhesive, which is called a marine adhesive now because it will stand up under wet conditions. So most of your plywood today is made with [resorcinol?] adhesive. And these defects were cut out and the patch put in and this was all done automatically in a conveyor.

Well with the Southern Pine the branches are very small and you can't make plywood out of it---it is very expensive to do so if you try. So what we came up with was a method of removing the damaged area and filling it with a foam type of adhesive. This was very easy to do, however, there was a problem involved in that the foam was difficult to determine how high it was going to be above the substrate surface and it sometimes foamed greater than you wanted it to and sometimes it didn't foam enough and whatnot. Well what we did, we determined that we could provide a certain density of that foam by restricting it, we would put just a sufficient amount of foam in there and put a flat metal piece over that area and restrict that foam from coming outside of the void and that would give it a certain density. Well we did a lot of that work to determine the density and determine what kind of a surface we needed to use so that ever time we wanted to patch a material, we could put so much of this foam material in there and put the restrictor plate over it and foam would harden and it would be of the density that was close to the wood density and we could overlay it with a fiberized type of covering---mostly impregnated paper.

Chet Restler was the project leader for that particular project and I was working for him at that time. Chet, before we finished the project, passed away and so it became my responsibility then at that time to finish the project. Leonard Selbo became my project leader and he really didn't do much other than I just reported to him occasionally. So I carried out the project for its entirety and put the research part of the studies out on the test fence in Middleton (Wisconsin). We had an area out there in which there was a fence that the paint lab put panels out there that were either painted or stained and they were able to get various climatic conditions that way. We had test specimens too that we put out there and one of them was the panels off this foam overlay foamed panel. If I put some out there that were kind of a raw state we called it. Some of them I painted over the overlay and they were in very good condition oh about ten years ago I was out there and checked them and they were still very good. But the ones that didn't have paint on it were bad.

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