Advice needed - Fiberglass/Epoxy shaping and filling(?)

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ptsmith
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Advice needed - Fiberglass/Epoxy shaping and filling(?)

Post by ptsmith » Thu Jun 14, 2018 8:55 pm

Hello, Builders!

I am happy to say I've finally made it past fiberglassing day...after two years...and it's only the outside. But, overall, I'm pleased with the results, and very proud! One of my positive affirmations, as my father and I worked through the day, was "we're going to make a few mistakes, and no matter what they are, we won't be the first!" Knowing that, I embraced that the end result would be sweet, but I'd have to be awfully lucky to reach perfection on my first canoe.

Anyway, I'm pretty sure I didn't understand just how much I'd have to squeegy out of the wet-out. That is, I'm certain I used too much epoxy on the first coat (and every coat), which resulted in the FB cloth being close to the hull, but perhaps floating in some places. Additionally, there is quite a bit of waviness along the starboard side along about 4" of the sheer. Knowing I'd have to do some minor (and major) shaping of the end result, before varnishing, I formulated a game plan and hoped for the best.

Below are some pictures of a few problem areas. Again, I believe these were created due to a poor squeegy process, and/or slight wrinkles or waves in the FB. I've gone over then with a sanding board with 80 grit paper and a carbide scraper to knock-down the ridges. I went back and forth with the board, then scraper, and repeated a few times until I started to hit glass ( :mad ).

I'm looking for advice on how to tackle this...? Should I proceed a bit longer, then build up some more epoxy? Do I have to add another fill coat to the WHOLE hull, or can I concentrate on a section? Please don't tell me I'm going to be stuck sanding these spots down until flat, then patching them and feathering... (or do tell me if that's the only way.

Image

Image

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As always, thank you incredibly much for all of the advice. I promise I spend a TON of time overwhelming myself with information from past posts, and I'm sure there are dozens of posts on this exact issue.

Patrick

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Patricks Dad
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Re: Advice needed - Fiberglass/Epoxy shaping and filling(?)

Post by Patricks Dad » Thu Jun 14, 2018 10:09 pm

yup. you have some waviness in your glass. It looks like you stopped sanding fairly soon after you hit the glass. If you get it wet does some of the glass disappear? If so, another coat of epoxy in those areas will help. It's hard to tell from the pictures how high the glass is off the hull. If you want to get rid of the problem entirely to create a fully flat surface, you will have to either add enough epoxy to the low spots to raise the level to match the places where the glass is high. That may be an awful lot. Alternatively, you could sand it off (through the glass) to get to a flat surface and then patch it with piece of glass and feather it out. A final alternative is to hand sand the remaining glossy surfaces (after adding another coat to the exposed glass) and leave it wavy and varnish normally. It will always be wavy and visible but structurally sound.
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Jim Dodd
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Re: Advice needed - Fiberglass/Epoxy shaping and filling(?)

Post by Jim Dodd » Thu Jun 14, 2018 10:22 pm

Tolerance.
Every builder has to decide on the level of tolerance they will accept.
I'd finish sanding, and Patch the areas, that I end up with bare wood showing. Scrape, and recoat with at least two fill coats of epoxy.
Wait a week and sand.

One of the reasons, I've gone from Squeegees to Cigar foam rollers .

Jim
Keep your paddle wet and your seat dry!

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Re: Advice needed - Fiberglass/Epoxy shaping and filling(?)

Post by Cruiser » Fri Jun 15, 2018 8:12 am

+1 on sanding flat and patching/blending as required. +1 also for roller application.

How much you finish is related to how critical your eye is, you are noticing and are concerned about the waviness, that will always be the case .... so best to just fix it now IMO.

Carbide scraper for the bulk of the removal, followed by a flat bottomed sander of some sort (sanding block or equiv) you want to avoid anything that follows contours if you are trying to flatten an area .... otherwise you sand much deeper than you need to ... the idea would be to remove the high material only.

If you haven't used and blended a patch before, a few pics of adding extra layers at the bow to demonstrate how well that can work.
2 layers added
Image

Edges leveled/blended
Image

Very light epoxy coat, applied with a roller
Image

You can get an idea of just how well this works

Brian

ptsmith
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Re: Advice needed - Fiberglass/Epoxy shaping and filling(?)

Post by ptsmith » Fri Jun 15, 2018 6:04 pm

Gosh, you guys are super helpful. Thank you.

Brian, your pictures are selling it. It sounds like the right way to do it is to sand/scrape it flat, and cover the area with another layer of glass.

Could you guys help me by reviewing the process? Keep in mind, this is much of the length of the boat, about 4-6" of the hull above (or below) the sheer. I imagine I have to:
1) Continue sanding and scraping to eliminate high spots, regardless of getting into the weave.
2) Sand the rest of the hull as planned
3) Cover the entire area of concern with new e-glass such that it can be blended/feathered later. (This could be a strip about 10' long and 6" wide.)
4) Fill with Epoxy, just as executed originally, but better. :cool
5) Cure, sand, etc.

Does that sound right?

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Re: Advice needed - Fiberglass/Epoxy shaping and filling(?)

Post by Cruiser » Fri Jun 15, 2018 8:10 pm

That looks like a good plan, BUT it will all be predicated on getting the existing application flat and accessing whether you have indeed compromised the glass layer. It would seem this is likely, I just want to stress to take it 1 step at a time.

Keep us updated on your progress and we will second guess you (jking) .... but keep us apprised and we will offer what assistance we can.

Brian

ptsmith
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Re: Advice needed - Fiberglass/Epoxy shaping and filling(?)

Post by ptsmith » Fri Jun 15, 2018 10:14 pm

Thanks, guys, for the advice. I will get to sanding and post when I have a better look!

ptsmith
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Re: Advice needed - Fiberglass/Epoxy shaping and filling(?)

Post by ptsmith » Sat Jun 16, 2018 9:43 pm

Gentlemen,

I've spent the evening working the hull flatter with a sanding board, and carbide scraper, and I think it's time to check-in. The area of concern is much flatter, and only a handful of problematic areas remain. Much of the "waviness" is reduced to the area that will be covered by the outwale. That said, there's still some work to do, and I'd like to revisit my options and request your advice!

Below are pictures of the worst areas...
Image
Image
Image

Note the spots in the last two images that show fiberglass "rings" which likely indicate that I've sanded through the FB cloth... If that is so, I have to say, it happened without much effort. Keep in mind the scale of the strip height to show the size of these exposed areas.

At this point, I believe my options are:
1) Continue as planned above and patch these areas with a large strip of FB cloth.
2) Fill these areas with a couple more coats of epoxy and sand smooth.
What do you guys think?

One more thing... as I read through the "Sanding the Epoxy" section of Canoecraft (pg 158-160), I found myself confused by something Ted Moores explains. He mentions in Step One (pg 159) that " Because the epoxy follows the weave of the buried fiberglass, you will see the pattern of the cloth emerge as you begin to sand. The pattern will become more distinct as the sanding levels the epoxy." He continues in the next paragraph to suggest that, "you will completely sand away that pattern before you reach the fiberglass itself."

What pattern does he mean? There's an image to support this section, but I cannot make out the detail. I assume he does not mean the pattern you see in the above images. Can anyone clarify what he means? :thinking

Again, sincere thanks for the guidance. I don't know what I'd do without this forum... Also, happy Fathers' Day to all the dads! :tu

Patrick

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Re: Advice needed - Fiberglass/Epoxy shaping and filling(?)

Post by Cruiser » Sun Jun 17, 2018 8:37 am

IMO you shouldn't worry about fixing as you go along, just creates a lot of problems. Finish the flattening process, then do the assessment, on how to deal with the end result.

Your pics look like you are at the pattern Ted mentions and haven't got to the FG itself yet. If you think about the waviness you describe, you will be cutting through epoxy and FG in a pattern consistent with what ever wave you are flattening. if the FG isn't pressed flat to the wood, then you could get that sort of pattern showing. It is starting to look like maybe one issue may be the initial squeegee step, leaving too much epoxy and not pushing the FG against the wood tightly.

I suggest you continue on with your current plan, wait till you are done, before you take further remedial action. If you can avoid cutting through the FG (it will go all white, hard to miss), you may get off lucky with just needing a thin coat of epoxy as a fix (that and all the muscle you are currently expending).

Brian

ptsmith
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Re: Advice needed - Fiberglass/Epoxy shaping and filling(?)

Post by ptsmith » Sun Jun 17, 2018 8:50 am

Fingers and toes crossed! Thanks, Brian!

sedges
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Re: Advice needed - Fiberglass/Epoxy shaping and filling(?)

Post by sedges » Sun Jun 17, 2018 7:08 pm

Patrick!

A tough situation to deal with at a time when more progress toward finishing would be desired. Your patience with solving the problem is good!

I agree that you need to finish the flattening process. You are close. It does look like you have breached the glass already and those spots will get bigger as you finish flattening. It will compromise the strength of your hull and a patch to cover would be necessary. You still have the inside to do and it will be good if you can avoid the waviness there. Also, there may still be quite a bit of cloth left in the low spots. If you used 6 ounce cloth, I recommend patching with 4 ounce which makes it very easy to fair the edges. Even a 2.5 ounce cloth would be good.

Backtracking a bit. I feel the reason for the waviness might come from not trimming the cloth close to the hull edge before glassing. The flat cloth has to conform to a curved surface by the fibers rearranging themselves. If there is a cut edge it is much easier to get the wrinkles and puckers out than if there is a foot of cloth beyond the hull. I learned that the hard way long before there was such a handy forum to learn from.

ptsmith
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Re: Advice needed - Fiberglass/Epoxy shaping and filling(?)

Post by ptsmith » Sun Jun 17, 2018 8:00 pm

Sedges,

I planned to use some scrap 6oz cloth from my original lay-up to patch these spots, by stealing from the remaining cloth to be used on the inside... I'm nervous about taking any from the reserves, though... nervous I'll drape it in the hull and realize I took too much! Do you have any good sources for grabbing 4oz cloth?

I agree with you that this probably was (at least) compounded by having too much cloth overhanging the hull. As this extra cloth absorbed epoxy, it put a tremendous amount of strain on the cloth along the sheer, thus creating the issue. Unfortunately, this (fiberglassing) is the one and only step that seems to be without the option to push the reset button (without building another boat)!

Can anyone point me in the direction of a good resource on "feathering" layers of fiberglass? I've done some quick research and haven't found what I'd call a core resource, but several mentions... Anyone know of one they'd be able to share a link to?

Thank you,
Patrick

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Re: Advice needed - Fiberglass/Epoxy shaping and filling(?)

Post by Cruiser » Mon Jun 18, 2018 8:46 am

Patrick, I am not sure a "core resource" for that is really available, but it is a useful skill to have in your bucket.

It really isn't that big an operation, to warrant it's own subject .. I will try and describe the process for you.

- Measure the area for the application and add about 1" extra to overlap the existing applied epoxy/glass
- make sure that all of the area has had the shine removed (sanded)
- cut a piece of FG suitable for the area to be covered
- lay or tape the FG to the patch area, if you use tape, put a second piece on the sticky side where the tape transits the FG edge, so it doesn't fray the edges
- mix up the epoxy and apply to the FG, once wet the FG should stay put ... I would use a roller for this operation (my preference) and roll from the New FG to old when you wet the edges
- this first coat should not be applied "heavy", enough to wetout the cloth .... the pictures you posted show a lot of epoxy on the boat, the epoxies job is to saturate the FG .... by itself it adds little to no strength
- once setup (3-4hours or so depending on your epoxy) apply the next coat ... this one is just to fill the weave, so not heavy, squeegee excess off once it starts to kick (~20 minutes)
- at this point, I would leave it overnight to cure .. there should only a a little weave showing
- next day use your carbide scraper along the edge, you want to start to knock it mostly down, forming a ~1/2" wide bevel
- just take your time and concentrate of establishing the bevel, you are done at the edge when the edge disappears (is level with the existing FG) into the older FG layer
- lightly sand the patch area, extending over the beveled area and onto the older layer by another inch or so, keep the sanding line a bit irregular
- now add 1 last epoxy coat with the roller, this one can be a little thicker .... don't be too generous, just a little thicker
- check area for the next 30 minutes and touch up if there are any runs .... there shouldn't be any unless you applied to heavy, but keep checking till it all kicks off and then leave it over night

You may want to try doing a small test patch with a couple of FG scraps ... apply one to piece of wood, apply a second one offset a couple inches to give the edge .... practice scraping this edge before you move to the boat. You prep this test patch at the same time you do the patch and use leftover epoxy.


Brian

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Jim Dodd
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Re: Advice needed - Fiberglass/Epoxy shaping and filling(?)

Post by Jim Dodd » Fri Jun 22, 2018 10:24 am

We are building a canoe, at our local wood shop. I just feathered the cloth on the extra bottom layer, and two Bias strips on the ends, this morning.
I would do the same thing for a patch !
Tip, use a Carbide paint scraper, and do it within a day or so of glassing. The resin is relatively soft, and scrapes easily.
The canoe will be left alone, for a week, before we start sanding. This allows the resin to cure, and not gum up sand paper. A shop vac is hooked up to the sander.
I took a few pics, but left the camera at the shop.

Jim
Keep your paddle wet and your seat dry!

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