Proper Glue

[Spike]

Greetings!

I am in the process of restoring a '48 Mahogany Runabout. I will be using some of the old ribs and frames. I will also fashion some new wood, mahogany splints to fill the screw holes. My question is what is the best kind of glue or epoxy to use for the holes? I have Titebond ll, a one part, waterproof "premium" glue. Is that apprropriate for this application?

Spike

Your thoughts are appreciated.

[Bob Smalser]

The best way I know of to fill old fastener holes is to get a plug cutter bit set and Forstner bit set that match each other.

Then you simply drill a blind Forstner hole with a nice square bottom....cut a bunch of matching plugs from planking scrap....cut them all at once on the board's face, affix wide masking tape to the plug board's surface, flip over and remove the board, and all your plugs are neatly lined up with grain orientation.

Then epoxy in the plugs, lining up the grain, using a good boatbuilder's epoxy.

Use good stops for the Forstner and Plug Cutter...and you don't even have to sand...simply wipe excess glue off with a vinegar-dampened rag.

But when in doubt, cut them long and pare them off...nuthin looks worse than pock marks in a finished surface.

[Bruce Hooke]

Am I correct in thinking that we are talking about small screw holes (i.e., the threaded end of a #12 or smaller screw) in areas that will not be highly visible? If so, I would simply whittle wood 'sticks', dip them in thickened epoxy and jam them in the holes or better yet use a syringe to insert a little epoxy in the hole and then jamb the stick in (that way you are more sure of getting epoxy down to the bottom of the hole). I would not use Titebond because it is not as effective at gap filling as thickened epoxy. If you have a lot of holes to fill you could cut thin square strips on the tablesaw and then just break pieces off the strips as necessary.

For larger holes or holes in surfaces that will be bright finished, I would go the route Bob talked about. Also, if the screws were very corroded or if the wood around the holes is otherwise in bad shape then the plug cutter approach might be wise so that the epoxy has clean wood to stick to.

The reason I would not use the plug cutter method for small, clean, hidden holes is two-fold:

1. I think the method of jambing in thin sticks is quicker than drilling a hole and cutting a plug.

2. A plug glued into a board will not be as strong as the unaltered wood would have been because there will always be some end-grain to end-grain surfaces in the glue joint beween the plug and the hole. It follows that the smaller the hole the better, and the smallest hole possible is the unaltered screw hole.

[Bob Smalser]

...and rethinking your question after reading Bruce's response...I've done both at once...an 8th-inch dowel pointed on the disk sander driven into the hole and cut flush on both sides...followed by my plugging routine.

Partial holes left on the inside can become water and rot traps.

And for painted surfaces, thickened epoxy alone does a decent job on the small ones. Read the West Marine free booklet on how to do it, forst.

[Spike]

Bruce and Bob~

My question was not clear, and you did a great job figuring it out. Yes I am filling old screw holes #8 and #10 that were in the frames and ribs. These held the topside planks, battans, and deck. I have some Titebond glue that I thought I would use. Sounds like epoxy is a better meduim.

Danenberg in his book mentions to use a "marine glue," but says no more. That is why I ask.

[ 01-15-2004, 09:16 PM: Message edited by: Spike ]

[Ian McColgin]

For general application, it's best to get used to one of the better propriatary epoxies and use that system. I happen to use WEST, but Cold Cure, System 5 (?) etc are also good. Mr. Smith of CPES fame has a great line of products if you can think ahead and mail order his stuff.

You can't get this stuff in normal hardware stores.

There are subtle differences between the various propriatary epoxies that amateur boat building is unlikely to ever reveal. All of them are abundantly strong for our applications. The differences really come down to user familiarity. All of them can give a bad bond if mixed incorrectly. Each has its little quirks in handeling. Get used to one brand that you have good access to and stick with it.

G'luck

[Keith Wilson]

Epoxy has been the glue of choice for boatbuilding for quite a long time. Resorcinol glues are arguably better, but fussy and require very accurate fits and lots of clamping pressure. Epoxy fills gaps, is as waterproof as anyone could want, and once cured, cleans up nicely with a heat gun and scraper (softens with heat). The best short reference on epoxy I know of is System Three's "Epoxy Book"; everything you need to know about it in twenty pages or so. Here's their web site; (http://www.systemthree.com/index_2.asp) ; you can download the book as a .pdf file if you like. I use their T-88 glue a lot, and am completely pleased with it.

[Frank E. Price]

Epoxy is overkill in this situation. Weldwood powdered glue is much cheaper and easier to work with, and if you care to be obsessive about having a true restoration is more appropriate to the boat's origins.

Frank

[Spike]

Frank and all , I truly appreciate you comments. With all the hupla, I haven't gotten my question answered..........

Most of you mention epoxy, however can I use Titebond ll?? Again, Dannenberg recommends a "Marine Glue." No brand mentioned. Help......

[Bob Smalser]

"...can I use Titebond ll??"

OK....frank answer?

No. "Waterproof" and "water resistant" are only part of the story.

Having repaired almost as much joinery as I've made...and hundreds of gunstocks...I'll offer the following:

Once you contaminate the wood with Titebond or other alpihatics...you'll rarely be able to reglue it successfully if you ever have to. Awful stuff come repair time. And during repairs, you break the glue bond with water...so what does that tell you?

Epoxy can be reglued after keying the surface.

Resin glue isn't as bad as aliphatic to glue over...just almost as bad. But it's also brittle, eh? And it's a poor outdoor glue...not to even mention using it in exterior boat joinery. Of all the resin glue joints I've had and seen fail out in the weather, I was never able to figure out whether it was the water or the expansion that did it....maybe somebody else knows.

Moreover...nothing out there matches epoxy in flexibility...read Anastasia's thread on Bondo...having the gluebond fail because of seasonal expansion, and water get in there is where the rot will begin.

I use poly's for outdoor and green wood applications...but they haven't stood the test of time that epoxy has, and I won't (probably ever) use them in boats below the waterline...nor does the manufacturer or any competent authority I know of recommend them for that. It's "gap-filling" reputation is a misnomer, from my observation, as the foam is porous. It's also a third+ less the strength of epoxy.

If you are filling a hole...use a wood plug if big enuf with epoxy...and thickened epoxy for the tiny ones, following the West System free booklet...

...and you...or more importantly, someone like me...will probably never have to cuss your repair.

[ 01-16-2004, 09:51 PM: Message edited by: Bob Smalser ]

[Nicholas Carey]

Originally posted by Spike:
...I haven't gotten my question answered...Most of you mention epoxy, however can I use Titebond ll?? Again, Dannenberg recommends a "Marine Glue." No brand mentioned. Help...Titebond II isn't waterproof. It's "water-resistant". It won't work for anything that's continually wet.

You should use a fully waterproof glue: epoxy, urea-formaldehyde (Weldwood) or resorcinol.

Polyurethane glues, like Gorilla-brand glue, might be also be an option, although they, too, aren't warranted for below waterline use. And I'm not sure I trust their little "foaming action". Unless you have a tight, thin glueline, I think it weakens the bond.

All these glues have their own unique sets of benefits and drawbacks. Both urea-formaldehyde and resorcinols require, for maximum strenght, thin gluelines (on the order of a few 1/1000ths of an inch!) and high clamping pressures (in the case of resorcinol, the recommended clamping pressures are 100+ psi).

For what want to do, I'd probably go with epoxy. It's well-tested, it doesn't demand well-fitted joints. It has a long open time (with the right hardner.)

And, for what you're doing, the plugs are never going to be removed.

[Spike]

Didn't mean to sound gruff.......... smile.gif
Thank you! This is tremendous information. I'll bag the glue and find some expoy for this application.

[Allen Foote]

Dan Danenberg....has a few mistakes in his tome, but as for this one, only an epoxy with penetration would be warrented to plug a frame. The idea is NOT to "glue in a plug to fill a hole" BUT to add strength with the epoxied plug, to the frame. Would you want to run a screw into that wood plug, fastening on a bottom plank, knowing that it was glued in...-VS- running a screw into a strengthen frame member acting as a single entity.
Bob answered your question just fine in the first post. Perhaps, the only thing to add is.....use west system epoxy with a bit of thickner (such as the High-Strngth bonding #) and drill and plug using 3/8" anything smaller and the plugs tend to break, anything larger (1/2") is excessive for a #12 screw hole.

[ 01-18-2004, 11:27 AM: Message edited by: Allen Foote ]

[Lazy Jack]

I don't get it. Spike asked about using Titebond II to glue pegs into the old planking screw holes and the majority of the responses strike me as a rather bit over-engineered. Why wouldn't titebond be perfectly adequate? What would a glue failure really mean in this context? Once the frame is planked over again where is the peg going to go? Why is it neccesary to use glue at all? Why not just drill an 8th inch hole and drive in an 8th inch dowel?

[Spike]

The optimal would be to replace the entire frame, or the rib with brand new wood. In many cases where by this is not possible, repair is necessary - holes and all - 50+ year old wood. From the posts, epoxy as a bonding agent is superior to any "marine glue" suggested by one of the professionals.

The size of the plugs, and the size of the holes of the screws are to be considered - as well as the purpose of the fastner-- bottom planks vs. deck, etc. Think we all agree "to add strength with the epoxied plug, to the frame" is the goal.

[Bob Smalser]

Originally posted by Lazy Jack:
I don't get it. Spike asked about using Titebond II to glue pegs into the old planking screw holes and the majority of the responses strike me as a rather bit over-engineered. Why wouldn't titebond be perfectly adequate? What would a glue failure really mean in this context? Once the frame is planked over again where is the peg going to go? Why is it necessary to use glue at all? Why not just drill an 8th inch hole and drive in an 8th inch dowel?It's important because even in a 1/8" hole, any failure of plug or glue bond will allow water in and rot to begin quickly, as the wood fibers there are already crushed and vulnerable.

Titebond isn't a "marine" glue...only epoxy and recorcinol are.

As Alan notes, the problem with most plug solutions is that they are crossgrain glue joints...the wood working against the glue bond in seasonal movement, and trying to back out any driven, tapered plug. As an example, I often have to fill carpenter ant holes in old-growth cedar before use. I use a wash coat of epoxy under heat, then an immediate second coat of epoxy
thickened with high-strength filler, also under light heat to fill the hole. The only danger there is leaving a void in a hole to become a rot pocket, and that's where I use a plug or scarf - in holes I don't think I can't completely fill.

Got an email that pointed out that Weldwood Plastic Resin glue has lasted for decades in outdoor laminations. No argument from me there...but we're discussing crossgrain gluing, not edge-joining or laminations that move together and last almost indefinitely, even with hide glue. But resin glue, like recorcinol, isn't a good gap filler and needs some clamping pressure and dry wood to cure to spec. Epoxy is more forgiving.

As to this being overengineered...it's more an example of explaining all the "why's" of the recommendation to make it stick better. It takes just as much time and money to do the job wrong as to do it right...and I suspect that's why Spike asked the question.

[Lazy Jack]

I understand all that you are saying Bob and it all seems technically correct yet I still don't understand how a screw hole peg 'fails'. You argue that 'failure' of a less than 'marine' glue due to differential movement would allow gaps to form in the hole which would then fill with water and cause a rot pocket. Yet this isn't a problem with stopwaters is it? I was taught to make an oversize dowel of the driest piece of cedar in the shop and simply drive it into place without any glue at all. Why do 8th inch screwhole dowels have to be considered any differently than stopwaters?

If the purpose of gluing the peg into a screw hole is strenth restoration,is the strenth added by a peg loaded across it's grain really that significant? In other words, if that is what is keeping the frame together isn't it already shot?

This arguement is admittedly essoteric and Spike won't be sorry at all that he epoxied the pegs in place, he'll just be sticky. :D

[Allen Foote]

First off LAZY JACK....you don't use cedar in a mahogany frame.
You epoxy in a plug of the same species of wood.
Stop thinking furniture and house woodwork......this is boatbuilding and it is done differently.
The idea is "strength restoration" not "fill the hole".

[Bob Smalser]

When I make a stopwater I use soft and very dry cedar or pine in a perfectly cylindrical hole...the idea being that the soft wood expands and serves as a gasket.

Most screw hole repairs are dry, hard birch or luan tapered dowels driven into the hole in the softer planking, and the mechanics of seasonal movement work to drive them back out, stressing the glue bond. Add a non-marine glue to that and repeated soakings, and you have the recipe for failure.

I'm not saying you can't do it successfully, I'm just saying that it should be planned with an understanding of how the application will work or fail to work. When I do it, I try for like species, like grain orientation where possible and proper marine glue.

[ 01-19-2004, 10:41 AM: Message edited by: Bob Smalser ]

[Spike]

................or epoxy.

[Frank E. Price]

The frame has holes in it that were filled with screws, are now empty and will be filled with splinters and some glue. Right?

The glue/splinters plug will run across the grain and the holes will be full. If the frames are kept dry it won't matter what waterproof glue is used. Urea formaldahyde will work as well as epoxy or resorcinol and is cheaper and easier to use, as long as the site is kept dry and not boiled.

If the frame is soaked for a long period they will all fail eventually at the frame-glue interstice. Presumably the frames will be kept dry. Ergo, the cheapest glue sufficient to the task is just that. The others are overkill. Many in our enlightened era insist on overkill. I'm with the others.

Frank

[Allen Foote]

So Frank....you'll keep your wooden boat in a hemetically sealed and tempreture controled room?

"kept dry and not boiled"? You gotta be kidding me.

HEY....You can jam what ever you want into your frames.....but don't even think of asking me to come aboard. Because, if thats how you'll handle that simple task.....I can just imagine how you maintain your engine and sea cocks and rigging and life jackets...ect, ect.

For those who come here to learn how others (with boatbuilding experience) have dealt with this situation in a propper fashion and have repaired frames and deck members appropriately, then the answer to Spikes question is as BOB stated earlier. I preffer West System as opposed to any other glue.

"Stop waters" are exactly that...and used at JOINTS between pieces of timber....not as a filler for old screw holes. You are talking about 2 completely different things.

[ 01-23-2004, 12:44 AM: Message edited by: Allen Foote ]

[Frank E. Price]

I'm only kidding a little. It's common practice in this wet and cool climate in fishing boat and cruiser repairs to fill old screw and nail holes with a tapered square yellow cedar peg (cut out in batches on the band saw) and some monkey ****, no glue. Not elegant, but it works fine and holds up well.

Obviously a fishing boat ain't a mahogany runabout. I would still rather use no glue in that situation, and if the frames are so small in relation to the size of the holes that glue is necessary to attempt to regain lost strength it's probably a lost cause. The frames probably should be replaced if they're that small. And if glue must be used it doesn't matter which of the waterproof glues are chosen, so make it easy on yourself.

These kinds of repairs were made and made well long before epoxy became the cureall. Epoxy is a great glue, among other things, but better is not necessarily justified if the increase in performance is not needed, or if the increase in performance does not justify the increase in inconvenience and cost.

I realize that's not a persuasive argument to many in the new epoxy order, but it's a point of view that people need to be reminded of whenever they contemplate dumping more epoxy into/onto a boat. Often the money and time could be better spent elsewhere on the boat.

Frank

[Allen Foote]

But Frank,
You and everyone else advocating cedar splinters, are missing the point.
1)You DO NOT frame a boat with a soft wood because fastenings (nails and screws) will pull out.
2)You do NOT repair hard wood frames with a soft wood because screws and nails will pull out of soft woods.
Stop thinking about plugging the hole and think about the next step....what is going to anchor the new screw or nail. Thats why the "restoration of strength of the frame" is more important than filling an old screw/nail hole.

[Bob Smalser]

There are lotsa long-service boats of W. Hemlock along the cold Pacific Coast from Puget Sound up to Alaska.

Those same boats wouldn't last 5 years from Virginia to Florida...the point being you can get away with things in cold climates you can't in the heat and humidity.

[On Vacation]

My oh my, what a thread for such a topic. Where do I start...............Second thought, Its all been said.

[Spike]

Yes, we have gone full circle with this topic a few times. All good thoughts. For my mahogany runabout, which is not a fishing boat, I will use mahogany slivers with epoxy. Period.

[On Vacation]

Mistake, my .02 worth. Thats my thought.