retreating treated lumber

The substance used is Chromated Copper Arsenate, and I believe is measured in percentage of saturation via a pressurized chamber. When you read the tag on the end of the board or timber, if it reads .40 C.C.A. it means that it's 40% saturated with the C.C.A., used to have a blue tag. This was the most common saturation, yet I have seen 12" x 12" timber that was .60 C.C.A., industrial grade, had a red tag, color coding must have been specific to that manufacturer, don't think it was an industry standard. Reason I mention it, is I spent 4 years working for a lumber company, soon after high school, mostly delivering materials, also picking up materials from the manufacturing facilities. I used to pick up full trailer loads at one large treatment plant. They use a very large pressurization chamber, and place entire units in the chamber, not sure how the C.C.A. is actually applied, but it's amazing how it saturates the entire unit.

Most common species was southern yellow pine, kiln dried & unitized, then placed in the chamber for a specified time. We used to get some soaked and saturated units, real heavy. Sometimes that C.C.A. would be so saturated in some of the smaller dimensional lumber that it would be crystalled up on the ends, and if you were to break open a unit of 5/4" or 1" nominal decking, any thin dimension material, in the heat of the summer, it would curl up and bend if it dried out to quickly, we used to lose all the top boards and I can recall the messy stacks of warped, curled and banana'd boards. I would believe that by using common sense when handling and building with pressure treated lumber, there is not much to worry about. Use a dust mask when cutting, wear gloves, eye protection etc. Follow mfr's safety protocol, MSDS sheets etc. I used to prefer to build with it when it was still wet from the plant, but not so much it would mist up a cloud of C.C.A when cutting. Fabricate and fasten down before it dried, matter of preference but it seemed to dry fine without distortion if used wet, better than losing material once on the job because it dried out too fast and warped.

I recently used 6" x 6" 's that were treated in the 70's when P.T. first came out, I treated the ground contact area with creosote and used motor oil, for pole barnm posts. Ground is well drained, I saw all the poles that came out on the powerline right of way at our place, they looked new, so I think in this area, where soil is well drained, as long as the wood has some decent protection it will last.

I keep hearing rumor that the pressure treated lumber process has been changed or will be phased out, not sure what the deal is there. Creosote is long since unavailabe to the consumer, so now it's back to home brewed treatment methods. I never thought any of these treament methods were hazardous if used responsibly, but I guess the EPA knows better, or people acted carelessly in the manufacturing or end user process, am curious too as to what the best treatment process is still available be it manufactured or home brewed.

They use a different chemical now (ACQ) which we'll probably be told is worst thing since DDT in another 15 years when we're worrying about the glaciers descending on us from the next Ice Age.

I remember decades ago reading about a home-brew treatment method for ground contact posts which I thought sounded effective, but slow. The chemical treatment solution was heated in a 55 gallon container over a fire, the posts standing in the solution. Once the solution had reached the boiling point, or some lesser temp, the solution was allowed to cool with the posts still in it. It was supposed to be a way to promote greater absorption of the chemicals where pressurization was not possible.

Stan

I've heard of the immersion methods, but not of boiling, have to wonder what the solution was made of though.

I was fortunate to have small quanity of creosote on the shelf, and boy did the ends of those timbers soak it up. Used oil as well, soaked it up on top of the creosote, but I doubt either fully penetrated. I'm not sure why creosote or coal tar was considered so dangerous and banned, but then I'm no chemist. Probably had everyting to do with people making open pits in the earth for immersion, including utility pole manufacturers who did the wood preserving. Years ago, I still cannot understand the lack of care or knowlege about contaminating ground water, all the dumping and anything of the like, including unlined landfills etc. This has to be why so many of the substances that were seemingly safe to use if done with care and responsibly are now banned. Again, can't say I know much of the topic but it sure would be nice to have a product like creosote or similar available to someone who would use it responsibly. I'm not sure if a substance like creosote once applied to the wood, presents a problem by leaching out, as that would be a concern, but look at all the utility poles still in use. I stayed out of that other thread where the guy wanted to apply used oil to the barn, that was a hot bed of coals ! Seems like it would be ok, as any barn when the wood is dried out is a tinderbox any way, but would the applied used oil leach out ? If it did or could, not a good thing to use. Sure it would increase the flammability (if there is such a word) but once they get started there is no putting them out anyway, at least from the ones I've seen that have gone up.

2 things come to mind when treating posts for ground contact, soil conditions and insects. Seems that in well drained soils like we have here, posts will last a long time, and the fact that insects don't like these kinds of preservatives, makes one believe the process works. If in a high water table, or wet soil I have to believe posts may not last as long. Carpenter ants are the only ones that present a problem here and they only go for certain types of wood in certain conditions. The insects seem to be easy enough to control in this area.