CPES on window frame

I found a little soft spot on my inside window frame. I'm planning to use CPES to fix it, but am wondering if I should remove the glass first. I'd hate to epoxy the pane in place, but then there SHOULD be a layer of caulk in between the frame and the glass. Any comments?

We use CPES on our frames as we continue our ongoing project to overhaul all the windows on our boat. However we apply the CPES to the frame after it's been removed from the boat and stripped.

The caulk between the frame and the glass should in theory prevent the CPES from gluing the frame and pane together (if it will even glue them together-- I have my doubts). But it's anyone's guess what shape the caulk on your windows is in, and how thoroughly it was applied.

The instructions with CPES (we get ours from Rot Doctor in Seattle so I don't know how his instructions differ from the other makers of the stuff) say to remove all the finish and all traces of crumbly wood before applying the penetrating epoxy. We had a frame section that had some bad wood in it, so we sanded out the bad wood and filled and faired the low spot in the frame with the epoxy putty that Rot Doctor sells for this purpose. But this kind of work generally has to be done with the frame off the boat.

CPES doesn't penetrate very far into wood. If the spot you are trying to seal up is not actually adjacent to the glass, the chances are the CPES won't move through the wood far enough to encounter the glass. And CPES is different than "regular" epoxy. It's made to fill wood cells, not act as a super adhesive. So even if a bit of CPES does get between the frame and the glass I would be very surprised if it sticks the two together to the point where you would risk breaking something if you had to take them apart at a later date.

Why not do it right and rebuild the frame. I've done it several times over the years in places on our wooden boat. Have also gone the epoxy route. The effort, once you have dismantled, is about the same.

It's a soft SPOT. Maybe 2-3" of soft wood just on the inside frame. No need to rebuild it. Not even removing the glass. Removed the outer frame and will re-caulk and seal it from outside. Just wanted to stabilize the small spot of soft wood on the inside frame / trim.

Keith wrote:

It's a soft SPOT. Maybe 2-3" of soft wood just on the inside frame.

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One thing to consider is the depth of the soft wood.* As I said, CPES does not penetrate all that deeply into wood.* I don't know what your inside window frame is made of--- on our boat the inside and outside framework is mahogany--- but typical penetration of CPES in this sort of wood*is only 1/16" or less.* (So I've been told by experts in the stuff--- I've never cut a piece of wood with CPES on it to check).

As such it is great for sealing wood against moisture penetration.* But if the rot--- which is what I assume your soft spot is an indication of--- goes deeper than this the CPES will not fill it.* Hence the instructions to remove all rotten and crumbly wood prior to using CPES.

If I understand the action of wood rot correctly--- and I may not---- sealing the top of the wood will not halt the rot process down inside the wood.* Now if all*the soft wood in your frame*is 100 percent dry and the exterior of the wood is sealed so well as to prevent any more moisture from getting into the wood, perhaps the progress of the rot will be stopped.

The application of CPES to the surface of the soft spot after*it's taken down to bare wood*will harden it, or at least fill and harden the top 16th of an inch or so of wood cells.* Then you can refinish the spot and*that may be all you need to do.

But if moisture is getting into the frame somehow*and causing rot to soften the wood, I don't know what will happen in the long run even with the surface of the soft spot hardened with CPES.* It will probably hold up okay*for quite awhile, though.

-- Edited by Marin on Thursday 19th of March 2009 07:44:36 PM

According to the Doctor Rot website the CPES is one of the best penetrators, especially of rotten wood. From their web site

"Nothing will bond with wood better or longer than epoxy and no epoxy mix will penetrate wood better than CPES. CPES is composed of a premium, wood-derived epoxy and a complex mixture of carrier solvents which carry the resin into the wood. The carrier solvents gas-off and leave the wood fibers encapsulated with epoxy resin. Any paint, varnish, epoxy resin or polyurethane can then be used as a final coating."

And some more info

http://www.rotdoctor.com/test/penetration.html
-- Edited by Capn Chuck on Thursday 19th of March 2009 08:13:33 PM

-- Edited by Capn Chuck on Thursday 19th of March 2009 08:15:16 PM

-- Edited by Capn Chuck on Thursday 19th of March 2009 08:15:48 PM

Capn Chuck wrote:

According to the Doctor Rot website the CPES is one of the best penetrators, especially of rotten wood. From their web site

"Nothing will bond with wood better or longer than epoxy and no epoxy mix will penetrate wood better than CPES.

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I know this.* I've talked several times with the owner of Rot Doctor when we've picked our CPES up at his house.* But "penetration" is relative.* CPES does penetrate better than any other type of epoxy, but that just means that the other epoxies barely penetrate at all.

Bob Lowe is one of the most experienced wood boat shipwrights on the planet, having owned a boat yard that specialized in restoring, maintaining, and repairing wood GBs for many years.* He is an ardent advocate of CPES.* But he's the one who told me that it penetrates about 1/16" and he is certainly in a position to know.* The owner of Rot Doctor told me the same thing.* In the epoxy world, 1/16" or so is a lot.* If you have visions of this stuff soaking into wood like it's a sponge, I can assure you from using CPES for many years that it does not.* In fact, it's penetration characteristics into wood cells is almost identical to brushing on diesel fuel.

But that's okay because to do its job it only has to penetrate and fill the uppermost layers of wood cells.* And it does go farther down into the cells than something like WEST epoxy which is much thicker.

But unless you're using balsa wood or some other extremely soft wood, the penetration of CPES is not very much at all, particularly on harder woods like teak.

"But unless you're using balsa wood or some other extremely soft wood, the penetration of CPES is not very much at all, particularly on harder woods like teak."


Dont know about the commercial product you are ysing , but we always make up our own "Git Rot."

The trick to penitration is to use the mix on damp , not dry wood, and as Git Rot reccomends drill small holes to let it IN!

Any* std epoxy is thinned with alcohol 10% or so and when used the amount of slow hardener is increased by 10% or so.

The alcohol "chases" the water dragging the epoxy into the wood , the extra hardener is to make up for the space taken up by the alcohol.

Sopping wet wood doesn't work well as there would be too much alcohol needed to get to the water.

Try creating your own , its far cheaper and usually better than a re packager does.

But remenber even with epoxy its a patch , not a cure , so structural loads like wave tops should be avoided

FF

-- Edited by FF on Friday 20th of March 2009 04:29:07 AM

Keith, To answer your original question, the epoxy should not adhere to the glass enough to cause any issues with removal later. My limited experience with CPES and extensive experience with other epoxies has shown that with glass especially, this will not be an issue. Chuck

hiya,
** Mr. Keith, not much sticks to glass except silicone sealant.* That's why they use it for aquariums.