Douglas Fir Mast. CPES - use in restore/refinish?
I am presently stripping many coats of varnish from 40 year old Doug fir rectangular hollow mast. Varnish had broken down in many places and water certainly did track under the neighboring areas for some distance. All glue joints appear to be nice and tight.
Some such areas are stained black (on which I intend to try oxalic acid prior to serious sanding), others seem quite unharmed.
My concern is a few areas which ironically seem quite dry, where the grain has risen a bit (slightly fuzzy to the touch in spots), and I can get my knife in about 1/16" to 1/8" in places.
My question is whether it would be reasonable to coat the entire exterior of the mast with CPES, prior to multiple coats of varnish?
Obviously, I will not be able to coat interior surfaces. Further, many pieces of hardware and screws for sail-track, etc, will have to penetrate the surface, albeit with plenty of bedding compound (eg: Boat Caulk, or the like).
The goals of CPES application in this case would be to stop any rot, (if there is any active rot at this point), and increase strength if that is compromised to some dgree at areas described.
Thanks very much.
Douglas Fir Mast.CPES - use in restore/refinish ?
First question, Robert:How long is the mast. Next: How extensive are these areas of "slightly fuzzy to the touch?" A depth of 1/8th to 1/16 inch doesn't sound too bad. BUT if larger than the palm of your hand I suggest you trim out and scarf in new sections to correct depth.
However, although it's a long and messy job, and you have the patience (for safety sake) I'd split the mast into its sections and check that there is no serious interior rot or damage. (Forty years of wear is bound to have left its mark). Having split the mast and assured myself that the interior was sound, re-set (good epoxy glue) cramped and bound tight, then give it a good soaking in my favourite timber dressing:
1 part white spirit; 1 part linseed oil; 1 part clear commercial timber preservative. Apply until timber can absorb no more. You'll find it dries to a nice matt sheen - which accepts a varnish coat.
But wait until you get further replies. Bound to be wiser heads than mine... :cool:
CPES in the application you are suggesting, is really just an expensive paint, just clearish. For epoxy products to keep rot at bay, the whole of the piece(s), every side, every penetration, everything, needs a number of coats of goo. This encapsulates the piece(s) and prevents moisture and air from getting in to provide a nice environment for rot to live.
Anything short of the above is just painting. Douglas fur is difficult to sand smooth, the winter and summer growth woods are dramatically different in density and you'll have a washboard effect pretty quickly if you do any aggressive sanding. Scrapping is better, but the issue still remains.
After 40 years with traditional coatings (paint/varnish) I'd say there's nothing wrong with the methods that were employed. Sticking to these techniques will likely not harm anything and would be my way of proceeding.
I too would be interested in a look at the inside of the mast, but would base this judgment on how she behaved before you took her down for a good refinishing. Personally, I finish her off with the varnish of choice and step her up. If at some later point, seams started to open up, or other issues cropped into the mix, then I'd consider, splitting open the seams for a look see. An 1/8" deep, soft area is a conciderable percentage of the wall thickness on the avarage mast, so I'd think about scarfing in a repair in those areas. A small spot could be lived with, but anything over, say a 2" circle should be suspect. Epoxy would be a good choice for this repair.
I've used oil finishes and on some boats recommend them, but they don't last long before needing renewal and they don't take much abuse at all. On built up masts (like yours) I would recommend a harder finish, like varnish or polyurethane. Unless the mast is grown and on a work boat style rig, I'd not recommend an oil finish for the stick, just to much wear and recoating to keep up the protection.
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