As usual BOBL turns a relativly simple question into a long winded spiel on the Evils of "invisable dust" and other solutions that are way beyond most home workers.
The original question was about treated timber.
By far the best solution to the hazards of chemically treated timber is to not use it at all.
If you must use it, avoid working with it in ways that produce fine dust...and definitely avoid sanding the stuff.
In many situations the use of treated timber is pointless and superfluous.
Afterall the only reason we use treated pine at all is because it is cheaper than good weather durable timber.
In pine the various treatments penetrate quite some way into the timber..there are some that claim all the way to the core..but in practice that is not the case.
In hardwood, the treatment barely penetrates the surface.
SO as soon as you cut or machine treated timber, you need to retreat the cut portion to maintain effectivness.
so use of treated timber for turned or machined work is not a very good choice.
If you are dead set on a treated timber end product, the best way to do it is to machine and finish sand the item THEN treat it.
In manufacturing that is easy enough..the items are machined and put thru the treating process like all the other treated timber.
For us mere mortals, we can not use the same process, but there are similar but not the same products that we can use like "Selleys combat green" ( if it still exists).
Unless these finials are to be fitted and left unpainted, by far the best treatment is good old fashon paint and plenty of it.
Chemical treatment will not prevent splitting,cracking and being weather effected......but good old paint will.
All even better if you start with a weather durable timber rather than the pithy rubbish that they sell as treated pine.
cheers
