Deck Delamination / Core Problems

[ebb]

Mike,
Are you continuing with the recore.
More pics would be great!

Doubt that acetone would break any old frp down. Tho it might loosen things up if there already was some kind of deterioration. For yerself, breath as little of it as possible. If you can smell it, you're breathing it.

That's the reason to stay away from polyester: acetone and styrene.

There has been discussion about using solvents to clean up work. Concensus is that solvents can invade work and lurk in pores and screw up the mechanical bond between plastics. Even extreme volatiles like acetone.

{338 just had a puzzling epoxy to deck failure. I decide to fill in the depressions along the deck outside the coamings. It seemed pretty easy, tho arguably a waste of epoxy. The strip of decks have been sanded and cleaned off and on - the gelcoat anti-skid long gone, subsequent sanding showing a little of the glass in spots. As I do I scoured the hell out of the decks, dedusted by dry wiping and brushed on a coating of plain epoxy, the same laminating (runny) epoxy I always use. Then wiped off any runny stuff, mixed up some silica, milled glass, epoxy into a spreadable gel. I scrubbed in the gel first with a brush, and then bladed on a fairing layer of the goop.

Came back two day later epecting to scuff-sand and apply 407. It somehow didn't look right, so a 1" utility chisel came to hand

and, it took some work, but all it came off as if it was sugar candy. Pieces like broken peanut brittle. The pieces had the 36 grit scoring of the deck reproduced on the underside. NOTHING HAD STUCK. The deck in front and behind had hibuild epoxy primer on it (plenty of gelcoat still on the deck), no problem not sticking that I can see.}

Any ideas?

[mbd]

when you glue up the new core, don't forget to support the inner skin in position with some sort of structure or the core may sag while you and the core are supported by just the inner skin.

Thanks for the input Bill. I'm not too worried about the side decks since I have staging set up next to the boat. Still wondering if I can get away with the staging and small panels on the foredeck without supports. I still need to do some exploration to see how extensive that piece will be.

one of my friends needed to take a skill saw to the deck of his boat and start again after a first attempt to core the deck left him with what looked like sea-state 2 topsides.

Bummer! I feel his pain, though I must say, I got off much easier, albeit with a healthier dose of humility.

Any ideas?

Since no one else has chirped in, I'm maybe good for some questions. Is there a contaminant that will make epoxy not stick? Like wax or silicone? What do you use when you create a mold to keep it ffrom sticking? Any chance some contaminants could have been introduced in either of your mixes that could keep the batch from adhering? (Where's Mike Goodwin when you need him?)

[Theis]

Yes, there is. You can use Vasoline. I have also used wax paper. The glas sort of sticks to the wax paper, but the wax paper doesn't stick to the second surface. You can also buy a bottle of stuff the pros use from West (the Glass people, not West Marine, although West Marine carries it) It is a liquid that you brush on and it works very well to prevent adhesion.

[ebb]

someone did open my work cabinet at the boat and take my 407. Maybe they sprayed some release agent on the deck too. You never know what this world's coming to!

[Mike Goodwin]

Since no one else has chirped in, I'm maybe good for some questions. Is there a contaminant that will make epoxy not stick? Like wax or silicone? What do you use when you create a mold to keep it ffrom sticking? Any chance some contaminants could have been introduced in either of your mixes that could keep the batch from adhering? (Where's Mike Goodwin when you need him?)

Been sick, recuring "jungle fever" from my days of 'wearing of the green' and we ain't talking Irish here , anyway fever is gone and I can stay awake for more than 2 hours now.

Yes, silicone and epoxy do not mix , also wax , and the epoxy itself can blush and cause it not to adhere. When making a mold, you use a mold release agent , which is a wax and/or a latex liquid release agent or parting agent .

Hint, don't wipe down with acetone, use pure white vinegar then denatured alcohol , I have seen acetone 'soften' resins . Or use Prepsol or a mix made for glass prepping . And use a hell of a lot of rags , if you see something on the rag , it is contaminated, CHANGE IT ! or you are just spreading it around .

[ebb]

Think I'm gonna find a Pettit or Epifanes fiberglass prep cleaner to wipe down the deck befor epoxying again. Probably has acetone as one of the ingredients - could be that's what the etch part of the recipe is. The only place 40 year old wax could lurk on the deck would be IN the gelcoat. Therefor it is now dust.

There has been some work inside that doesn't seem stuck too good -a fillet piece that came out too easy - an end of a piece of matt tabbing that lifted too easy off old well sanded polyester. The inside of the boat could easily have wax laden surfaces. In 338 I hardly know anymore what layer we're at, besides 80% of the interior was painted (99% gone now), I would assume the Pearson paint wasn't sprayed over a waxy finish coat. The paint would be a good oxygen inhibitor. But, there might have been any number of scenarios installing the interior in 1966. Wax lurks inside the Ariel.

Will wipe both cockpit side decks down with solvent even tho the removal of the gelcoat would make it unnecessary. Also, There are various ages of part A around the boat, so it may somehow be 'old' epoxy that failed - but I find that pretty far fetched. I will use 'old' stuff ((the usual laminating epoxy I've always used)) on one side and new part A & B on the other and report back.

It's a warning.
Mentioned the failure partly to warn others and partly to confirm that I'm not the first (exploring the internet) to have the problem when remodeling. I've filled and made other repairs on deck with the same epoxy and fillers with no obvious sticking problem. Usually ignoring the gelcoat. Most of the deck has the high-build primer on it now I've been using - looks like it sticks real good.

Balsa core ends at the cabin. Deck is a complicated lamination. Could be when it was upside down in the female mold at the factory it had some strange things happening to it. Was the gelcoat sprayed over the whole mold without problems? The deck thickens at the end of the core at the cockpit. I believe, from porus holes in the plastic seen after gelcoat removal that that is a sign of heat build-up in the original work. Could that heat have fried the gelcoat? Maybe a few hot polyester pots got mixed up! Can't know, it's just, it's just, what did I do? Could I have screwed up my epoxy proportions? Yeah! Nah! Stuff set up jist fine, it jist didn't get close enough to what it was supposed to stick to.

[Mike Goodwin]

Silicon spray used to loosen a bolt or lube a track , silicon caulk around a leaking chain plate , silicon enriched paint sanded off and lots of airborne contaminates can be lurking about.
Could come off your clothes or from a leaking implant under a bikini.
A friend of mine had a custom body shop . He required everyone to wear Tyvek suits in the paint booth and all silicon had to be kept in the mechanical shop . With what he charged for a paint job , it better be perfect.

[ebb]

Silicone was used everywhere on 338: under the c'way trim, coamings and rails. All metal fittings were mounted with silicone. Couldn't believe the windows. Could be on the deck. Why spray it on the deck? Mike, great observation that sanding dust itself could be a contaminate! One assumes silicone migration into a surface only occures when wet, befor cure. Yet work procedures could easily produce the same effect. Could also assume that coating breakdown, age, sun, water could leech little silicone buggers into surfaces.

Silicone spray must be illegal.

Like at the Shuttle: "Zay Burkhard, use plenty of zillicon zpray on doz rusty release pins and on doz tiles, zo dey don't burn up on reentry - keep it away from da foam tho...."

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There are thousands of epoxy, silicon alkyd, and acrylic urethane inorganic coatings made with silicone that have better resistance to degradation from heat, UV, etc than older paints. Silicon and teflon are beginning to appear in bottom paints. Marine paints like Pettit's Easypoxy are "improved with silicone." The Navy is interested in the slick bottom paints as well as coatings with "low surface energy" for steel that will prevent ice from sticking.
It's possible that any industrial, surplus or marine paint could be used by now on an Ariel. And possible that any one of these paints could contribute 'silicone migration into the substrate.' Into the gelcoat.
My attempt at humor above is actually true. Columbia tiles are ultra engineered esotetric ceramics that are "10% fiber and 90% air." The tiles are coated with silicon paint, glued to a "fabric", which is in turn glued to the aluminum hull of the space utility vehicle.
Better write NASA to tell them why their tiles are falling off, right?

[c_amos]

Having tackled the starboard side earlier this year, I went into the port side today.

It was not to have been too bad of a job, as most of the foredeck core had been replaced by the prior owner (Herb Tucker) and his dad about 5 years ago. Apparently they had found some good balsa along the plywood strip that runs down the center of the deck, but unfortunately it has since found water and now fails the old 'acoustic coin tap test'.

So I set the circular saw to 1/4" and ripped down the center of the deck, a couple inches on either side of the strip of core that sounded soft.

The bond on the plywood strip was good, but I was surprised... no amazed, to find that there was very little bond at all to the closed cell foam!


I could see the edges of the air bubble that had apparently formed when the old skins were refitted.

Both Tim, and Mike caution against allowing any bubbles to remain under the skins if they are re-used.... I experienced problems on the starboard side where the old skin had been reused and the seam had allowed a minor leak.

I did not re-use the old skins when I re-repaired the starboard side, and will by no means consider re-using them when I close the port side back in. The stress point created along the seam, the possibility of bubbles (voids), and the less reliable bond between the old skin (that once was lined with rotten balsa core) argue against re-using the old pieces in my mind. More then any theory, the main reason I will not re-use them is that I believe they have contributed to my having to re-visit this job that the prior owner had done before me.

I sure hope this is the last of the balsa left in this deck........


also

Ebb said;

Silicone spray must be illegal.

Amen....

[ebb]

Hmmmmm,
Craig, have to look at that deck first hand. But sitting here it looks like not enuf thickened epoxy(?) was used in the recore. It probably was done all at once, the foam buttered, put in place, and then the lids put back on.
Any 'hurry-up' might have been the culprit.

It's a good idea in going with mat andor cloth on top of the foam. It definitely will be solid, even if you do the foam and later come back to do the top after the epoxy has set. If you are using non-blush, I believe you can expect a total bond two or three days later. Give you time to shape or add more foam.

The cut off lids, the original deck pieces, tho, have a number of layers of fabric in them that you will have to duplicate - to get the deck up to its original thickness and spec strength. 3, 4, 5 cloth pieces, depending on what you're using - and the epoxy. Was thinking that drilling a number of small holes in the pieces would help in the air-bubble-void department. You'd put enough pressure on them when reinstalling that the epoxy gel squeezes up into the holes as an indicator. Relieves the pressure too.

I would use just enuf thickner to gel the epoxy. Wet and loose. That may have been what happened with the recore you ran into. If there were other voids, the epoxy could have flowed and settled into those and left those spaces under the tops after they were squeezed into place. One hopes that plain unscored foam was used. (Small drilled holes could be introduced into the foam to make sure a bubble isn't captured under a piece of foam.)

The foam, if it is pvc, should make an excellent bond with epoxy.

If there is any lingering question about the strength of the new patchwork deck, a layer of cloth overall might give the job plenty integrity. Give us a look!

[c_amos]

Yur crystal ball seems to be working well tonight Ebb.

But sitting here it looks like not enuf thickened epoxy(?) was used in the recore.

What I intended to include but did not was that the epoxy that I can see on the edges of the voids does not appear to have much kind of thickening in it (pretty hard). Ironic, when I had asked Mike if he had misspoken when he talked about using thickened epoxy for this earlier in this thread (several months ago). Little did I know the question had so much to do with the repair the prior owner had done on my boat!

Anyway.... Yes. I will dry the foam core that I have exposed by removing the old skin, and cover it with several layers of mat. That is what I did on the Starboard side, and was able to match the deck pretty darn close (I can't see a difference).

The skin was not very thick (neither what I pulled off of the prior 'repair' or what I removed from the other side). Maybe an eighth at best, probably less then that. I used several layers of mat, and left the surrounding glass slightly proud. I then used a mix of west 405 and 407 filler thickened epoxy (still using up that darn west I bought for such a bargain way back when)....

I am gonna take the bow pulput off and re-bed it while I am at this... hope I don't find any more soft stuff..... I really would like to get the project list down into the low 30's

[ebb]

Craig, you know this, but for others a reminder.
A composite deck is stronger and stiffer than a solid deck would be. That may be arguable, but it certainly is far lighter.

If the foam does anything besides insuring a constant dimension of skin separation, it transfers the panel's thickness strength to the tension and compression skins. A solid spar is a lot bendier than a hollow one, as example. So the skins have to be a single unbroken unit. Even tho the inside can be honeycombed or closed cell foam the composite in total should be an unbroken unit. It seems almost that as long as there is a general separation between the skins there remains some integrity. I know of one Ariel that has been sailing with mushy decks for years without a problem. Strong skin must be the answer.

[c_amos]

Update;

Ripped up all the unbonded skin I could find and laid in new mat (several layers, different directions). Excised the 'seams' of the old repair, where the panels met and covered them with glass.

The seams where the original skins had been grafted together were a stress point, and had cracked...... the crack was not very visible until I removed material around it.

I am now more convinced that the method discussed in this thread carries the risk of future cracking along the seams. I have glassed them, and faired the repairs (lots of epoxy with fairing filler!).

I have removed all the hardware off the bow, other then the chocks (the boat is now in the slip with the lines shackled to the stem head fitting).

I plan to finish sanding tomorrow, and then lay a layer of light cloth over the top of the entire foredeck as further protection against these stress points.

I don't suggest that this is absolutely necessary, but even a solid deck is going to have some small amount of flex, and that flex is going to be felt more at any weak points you leave.... IMHO.

(OBTW, I have been using Mike's white vinegar / denatured alcohol cleaning solution... works great and easier on the skin then acetone... thanks Mike).

[tha3rdman]

I've sifted through this and the other thread that concerns recore. I had a lengthy discussion with a distributer, and he convinced me that replacing the balsa with balsa would be the best bet. He sites the compressive and sheer strengths of balsa vs the foams, and the need to go with a extremely high density to get the identical stiffness as the previous stiffness. It could be all smoke and mirrors, but for the cost comparision . . . I'm convinced that if one properly bedded the hardware in the first place the deck would not have gone soft. It's lasted nearly 40 years, and another 40 would be A-ok.

My question is about scarfing knowing a 12:1 or 10:1 is ideal, has anyone considered using a high grit (40 or 60) sanding disk to cut through the skin leaving the scarf and cut all in one swath. Versus circular sawing then having to sand the edges to obtain the scarf.

[ebb]

Don't know that you need to scarf anything, if you are using the word in its traditional way.

Suppose you could tilt the circular saw at 40/45 degrees to cut out the pieces so that if you are going to replace the original deck the pieces could be glued back like lids. However, the top skin of the deck is 1/8" maybe a little more if you're lucky. Any cut at any angle with a circular blade would cut more material away than the slant. IE the piece of deck/lid would be smaller than any hole you can cut. A grinder would be less accurate, unless you're thinking of using a dremel-tool.

I believe a straight 90 degree cut with a small circular saw and carbide blade set at a known depth would give you more control and accuracy. Use the grinder to vacate the tunafish - VERY careful not to grind thru the inner skin. Bedding the balsa in epoxy and epoxy gel (Epoxy, fumed silica, chopped strand*) will give you a strong deck without worrying about scarfing anything.

You may end up laminating your own deck skin back on top - rather than glueing the 'lids' back on. Conceivably it is stronger and more unified to laminate new deck back on top of the new core. Because you can marry it better to the remaing deck. However, it is conceivably easier to glue the deck pieces back on because you get an instant register with the remaining deck structure.

With the 'lid' method, after they're back on and the epoxy is set, you could grind a mild dip/depression around all the seams, three or four inches wide across the seam and fill it with strips of glass cloth and epoxy. Narrower strips in the bottom, with the next layer using wider strips. You'll only get maybe two/ three layers with the top one nearly grinded off for flush. This ought to graft the new work with the old pretty good.

With all new top laminate I would feather on to remaining deck by grinding a 'slope' on it.
This is what you meant by scrafing, I think.
It's not much, as the deck skin is so thin -just enuf for one or two layers of six or eight oz cloth to lap onto it. But with enuf buildup to grind the join down flush. Conceivably this is the stronger method. But I think it's a toss-up.

AND I always say this:
With work like this use only 100% solids laminating epoxy. Your supplier should tell you that it is NON-blushing and has so solvents or extenders in it. A great privilege of no-blush is that it will allow you to stop work and continue later without the penalty of washing and often without prep.
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*because the deck is horizontal, you need to thicken the epoxy filler only a little, just enough to control it. It should still flow so that it fills all voids and fills the baltec as well. Butter all pieces on all sides. Prefered method is to wet down/soak all surfaces with straight epoxy first, then butter. To avoid voids: You may find that drilling (for neatness) some holes in the center of panels, or where you know you have a depression to fill, that when you press the panel in its place the extra glue has a path to squeeze out like a relief valve.

Balsa with epoxy, imco, is as good if not better than expensive pvc foam for our deck restoration. Like you say, if you isolate it from thru fastenings, etc it'll last. The above method would isolate the balsa extremely well. Epoxy is a good waterproofer - and if you urethane the deck, whatz gonna happen?? And each panel is isolated so any water migration could not be a problem in the future. Some boats like 338, knock on wood, still have good decks after all these decades. Done right, new balsa composit should last a half a century! You know, like THREE generations!!
Sorry. Hope some of this diffuse stuff is usefull.