I am looking for some advice on how to fill some voids I found under the glass after removing a deck pad.

I am in the process of refurbishing an old foil board. Along with the usual wear and tear the deck pad had a hollow underneath it and a heap of water would get trapped there. The plan is to repair the various bits of wear and tear and old ding repairs, repaint and new deck pad. Maybe a new layer of glass over the high traffic and repaired bits and foil box areas for a bit more strength and integrity.

When I peeled off the deck pad, cleaned off the glue and sanded the existing paint I found a few delaminated heel dents, and some sand through areas on the glass. (The sand throughs look old so could be leftover from a previous repair job.) It is possible to push a pin through the sand throughs and about 15mm further into the core.

So, what to do with the voids under the sand throughs? Can the experts provide any good advice on this?

My options seem to be:
- Put some resin and glass over the top. Cover with a deck pad and forget them.
- Cut the glass away, fill with microfibre and repair as normal dings (the glass over the top looks sound so I would prefer to avoid cutting big holes in it)
- Drill some holes and inject resin into the voids (I think the voids might be too big for that)
- Drill some holes and use some spray expanding foam then repair the holes as normal ding repairs (cheap and easy and probably good enough).
- Try and do the same with pour in foam (sounds messy and expensive)

Thanks in advance.

This is what ive done , im no expert . But its works and easy .
Fix the deck solid .
Cut a 10 mm square hole in the deck where the void is .
Tools needed , 10 ml syringe and drinking straws .
Flatten straw end and sideways push to edge of void . Inject resin in to the straw until it flows out hole . ( syringes are so cheap , less than a dollar ea ) , This works good because it works from outer edges inwards . repeat on six or so angles . Put back hole plug , cover in plastic and put weight over operation , ( a bag of soil works good ).
ps, do this slowly and let it ooze . Too fast and it can lift the deck ,
pps , before doing anything , remove plug and let roast in sun for a few days , make sure its dry .

I can't visualise this - the sandthroughs are just glass exposed (what you would call a sandthrough on a surfboard) or glass is removed and there is foam exposed?

And are the voids big...?

Resin into large voids = not good due to heat.

I'm thinking fill voids with expanding foam and leave allt he original material there then 3 x glass over but depends on how bad these areas of nothing are...?

Board is wet / heavy? Can you show pictures of areas? I drilled and injected a whole hull with just pu glue, it held for some test runs. In your case, I'd drill, inject whatever foam of your choice (that doesn't eat the core foam!) and glass over. Put some nice and thick pads over it.

Thanks for the replies.

Here's a photo. I probed the hole and the pin penetrates about 10mm into the glass before it comes into contact with foam.

You can see around the edges where I have poked the resin with the pin and it's gone through the resin. There are other areas where the fibres are not exposed but poking a pin goes through.

My suspicion is that over time the water trapped under the deck pad has degraded the glass to make it weak enough to puncture it with a pin, or to sand the resin off. I don't think it was me being heavy handed with the sanding. It has only happened in a few places and the glass looks a bit dodgey in those areas.




I've got three kinds of things to repair.
- The biggest is a normal heel dent where the foam has compressed and the glass is no longer stuck to the foam.
- There's a few spots where the glass/resin is thin so I can poke a pin through it.
- A couple of areas where pressing hard on the glass causes it to flex up and down, similar to the heel dent but not as severe.

A pin pushed into each of the areas goes in about 10mm.

My inclination is to inject resin into each of the faults and see how it turns out. I suspect that most of the problems can be fixed that way. There's a relatively small amount of flex in the glass.

Even the largest the heel dent should only take 20-30 grams of resin to fill, which is tolerable. I'll apply some weight and stuff to squeeze the glass down onto the foam to reduce the size of the lump of resin.

If it sucks a heap of resin then I'll have to cut the glass and dig out the affected bits and rebuild it, but I would have had to do that anyway if the problem is serious.

The Board Lady recommends removing the foot pads, composite and damaged, compressed foam in the soft areas, rebuilding the foam with expanding foam or microfibre, reinstating the composite and finally installing new foot pads.

She says injecting epoxy resin does not repair the damaged compressed foam.

That glass rub-through only needs a couple of patches of 4oz over it with a bit of extra resin to fill the weave - if the foam underneath is solid. The green is PVC so its good.

Considering the risks of epoxy heat and the actual time taken to do things properly, I'd just do it rights. Get the heel dent areas and cut out the PVC layer then get the styro flat again with expanding foam and sanding. Replace the PVC foam layer with sandbagging and/ or really tight plastic masking tape to give pressure, sand it and glass over. Lots of glass in heel areas - you want about 20oz of cloth there.

I can post you some corecell offcuts if you want Gorgo

Injecting resin is generally a bad idea. The polymerization creates heat that can't go anywhere when surrounded by foam, so it melts the foam. You end up with a resin plug surrounded by air. The Board Ladey web site has pictures showing examples.

To decide on the repair, you really need to know how extensive the damage is. I played around with one board that had major delamination under the foot area. The sandwich was still ok, but the foam underneath was crash from heavy use in chop. I repaired most of it with PU injection, but one section by removing the sandwich and the broken foam underneath, and rebuilding it with pour foam and divinycell. The area with the PU injection only help up a few sessions before getting soft (and larger) again. The rebuilt section held up fine.

But in your case, it's quite possible that only the top glass layer is affected, in which case just glassing over would work, as Mark said. Pushing down next to the area with holes in the glass should tell you. If the foam under the sandwich is crushed, you'll know because everything will be very spongy.

Keep in mind that if you are fixing up an old board for foil use, a less-than-perfect repair may be fine, since there will be less stress on the board (you don't hit chop all the time like on a slapper, and you probably won't jump for a while). If you're just starting to foil, there's a good chance that you'll want to upgrade the board to a foil-specific board after a few months or a year, anyway.

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Mark _australia said..
That glass rub-through only needs a couple of patches of 4oz over it with a bit of extra resin to fill the weave - if the foam underneath is solid. The green is PVC so its good.

Considering the risks of epoxy heat and the actual time taken to do things properly, I'd just do it rights. Get the heel dent areas and cut out the PVC layer then get the styro flat again with expanding foam and sanding. Replace the PVC foam layer with sandbagging and/ or really tight plastic masking tape to give pressure, sand it and glass over. Lots of glass in heel areas - you want about 20oz of cloth there.

I can post you some corecell offcuts if you want Gorgo

I like this easy quick. I do have some issue that it may be more areas or SOFT spots ?

you will need to keep,a watchful eye.

many different methods can produce successful results.

The resin I use ,( surfset flex ) barely gets warm in the pot. It takes hours to gel so can be used to fill voids without melting the foam. They have a faster curing option , that may get hot. I still wouldn't fill thicker than 10 mm or so although I've had 40 mm thick pot left over that only slightly got warm.

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Manuel7 said..
... injected a whole hull with just pu glue, it held for some test runs. ...

Thanks for the PU tip. I should have thought of it myself. It's inspired a bunch of things I can do that should do the job.

I filled the smaller voids, similar to the one in the picture above, using foaming PU glue (Gorilla Glue).

I perforated the glass between the fibres with a series of pin holes. I put a bit of water on it and rubbed that in with a squeegee (made from a piece of milk bottle plastic), squeegeed in an amount of PU foaming glue (Gorilla Glue), then taped the plastic over the top and weighted it.

The result looks very good. The void is filled and the glass nicely sealed with little wastage, mess, expense or effort. There was no damage to the glass fibres. Most of the work was done sitting in the living room after morning coffee.

The dings were in edges and corners of the deck so there's no foot traffic on them. I will be applying glass patches and topping the deck with glass and a new deck pad so I am expecting that strength is not going to be a problem.

I have two more two large area spots to fix. I am inclined to try the same technique on them. It was so easy and clean and the results have been good. They will have foot traffic, but I am hoping the glass patches and deckpad will provide adequate protection.

I've got a fair bit of carbon left after a foil rebuild so I am toying with putting carbon patches topped with glass over the repairs. Not sure that is a great idea yet.

The PU glue foams to 3-4 times volume, but its not as aggressive as spray foam. Applying an amount to cover the damaged area and properly securing it and weighting it gives a dense feeling result. I can't press it down with my thumb. The PU is cheap and I had a small bottle sitting in the cupboard. Pour in foam might be better but it's expensive and you have to buy a litre of it.

Apart from mess, I'm not sure its all that much easier than doing a "proper" fix (cutting out the deck glass, routing out the crap foam, putting in new foam, reglassing the area). If you're set up to do that and doing a proper restoration project then I think that would be the go.

My project is more a cosmetic refurbish and I didn't want to cut into the deck and deal with areas around strap inserts and structures at the top of the Tuttle box. This lazy man's way of fixing dents and foam voids is cheap and easy and works well enough.

Yep, perfect. The pu glue likes lots of pressure so it can expand and have a strong bond. Forgot to mention the weighing part. Good job!