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Fiberglass question
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(Electrical)
(OP)
18 Sep 18 09:24I have a fiberglass structure with a very complex joint. Of course it's all gelcoated. The joint is about 30 inches long and tapers from about 5/8" down to 1/8". There is no way to remove the gelcoat in the joint.See my paint (LOL) sketch below. This gap needs to be water/spay proof.I'm thinking, get a piece of fiberglass panel, cut it in the same taper and epoxy it in directly to the gelcoat recessed about a 10th inch?Then glass it in. I hate to impact the face and don't care if the solution is flush with the greater surface.
Keith Cress
kcress - http://www.flaminsystems.com
(Mechanical)
18 Sep 18 12:30Wall? Floor? Ceiling?
What is behind, under, over the gap?
Does it need to be strong?
(Mechanical)
18 Sep 18 15:02Use 3M 5200 marine adhesive/sealant to fill the groove.
Ted
(Chemical)
18 Sep 18 16:07I am having difficulty visualizing this in 3-D. What is the dashed line?
(Aeronautics)
18 Sep 18 20:49If this is a composite facia panel, the standard method of waterproofing is to Caulk the joint, either with a silicone rubber , or a polyurethane caulk colored to match the panel, or depending on the job with a contrasting color to highlight the panel. The taper appears to be an installation error.B.E.
You are judged not by what you know, but by what you can do.
(Electrical)
(OP)
18 Sep 18 21:58Damn, you guys have lots of questions...Mint; It's a wall. The gap runs horizontally across it.The heavy line is all gelcoated fiberglass.Everything is just air and the fiberglass.It does not need to be very strong. The structure is pretty rigidly fixed in place and you can't deflect it with hard finger poking.hydtools; That is a capital idea!!Is there a volume restriction with 5200? Silicone would have curing problems with this large a cross section.Compositepro; Sorry about that. The dotted line is just a drawing aid denoting a 90º change in view.It shows a cross section of the joint on the left and what you'd see looking at the tapered gap from the front view.Maybe this will help:That's a regular 5/16" size screwdriver. This is 'wide end' and only about the first six inches of the tapering 30" gap.berkshire; Oh, it's an installation issue, no doubt about it.I don't see caulking as working on a gap this freaking wide.
Keith Cress
kcress - http://www.flaminsystems.com
(Aeronautics)
For more information, please visit China Animatronic Dinosaur Ride.
18 Sep 18 22:22When erectors put non structural panels on a building they will caulk gaps up to 3/4" wide, They use a foam round material called backing foamsee link: https://www.amazon.com/Closed-Cell-Backer-Rod-Roll... This is put into the gap to economize on the caulk . Choose the diameter to fit the widest part of the gap. after you get down to about 5/16" you should not need any. Wipe the Gelcoat with wax remover to remove any mold release and you should not have any problems ( Other than the bad fit of course..)B.E.
You are judged not by what you know, but by what you can do.
(Chemical)
18 Sep 18 22:29A two part highly flexible adhesive should be used. The 3M 5200 is a one part, moisture curing adhesive, which would take weeks or months to fully cure in this joint. That does not mean it won't work well enough though.
Plexus makes 2-part acrylic adhesives used to glue the deck of fiberglass boats to the hull. I have not used them myself, however. I'm sure all the big adhesive companies have products that will work. The key things to look for are:
2-part, for complete through thickness cure with little shrinkage.
Very flexible to spread stresses over large areas of differing bondline thickness without cracking.
Non-sagging paste to fill large gaps.
Good adhesion to gelcoat. Gelcoat may have release coat residue on it so surfaces should be abraded by wire brush or sandblasting.
Do not use any solvent containing adhesives as these shrink when drying and do not dry well in deep gaps.
(Mechanical)
19 Sep 18 01:50Epoxy mixed with coloidal silica and micro spheres.
Use a foam backer.
(Mechanical)
19 Sep 18 04:38Glue a tapered wood spear in with 5200.Prefinish a nice 1/4" red oak plank and glue that on the face.Urethane floor varnish works well, three coats sprayed on could look nice.
Mike Halloran
Pembroke Pines, FL, USA
(Electrical)
19 Sep 18 13:04You can't re-do it? I've learned that at a certain point I have to just bite the bullet and rip it apart and do it right if I want the final product to be correct and look good.
Any filler that just fills the seam will look always look like ass. Is this in a location where you normally never get a close look at it?
You say you don't want to mess with the gelcoat. Do you want this joint sealed? If you do, then you need a permanently flexible material that will stick to the gelcoat surface.
A foam backer and caulking or some other similar filler will close the gap and could seal it if you use the right material. You'd likely have to re-do it every now and then to keep it sealed.
To hid and seal it, grinding back the surface of the fiberglass 2"-3" on each side and then glassing over the seam could make it disappear permanently. That's a lot of work though and can easily compare to getting the panels installed right.
Assuming no sealing, you could fill it with a 2-part compound like an autobody adhesive or boat adhesive. Use rag with some solvent that will clean the compound but not damage the gelcoat to wipe over the filled material to both clean up excess and make the material surface smooth. Sand the surfaces down inside the seam to ensure this material sticks at least enough it doesn't become a loose chunk inside the gap. If you get a good stick to both sides, it could seal the gap too.
Again assuming no sealing, putting a square strip of material across the whole gap to hide it might stop it from looking like crap, assuming the piece makes sense there.
(Mechanical)
19 Sep 18 14:28A batten strip of FRP panel over the whole thing would be easiest.Attach with 5200 or epoxy.To get anything to stick really well to gelcoat do use a product designed to remove silicone and other mold release agents.For example https://www.westmarine.com/buy/interlux--fiberglas... Note: This stuff is one of the nastiest chemicals I have ever used. Ventilation+respirator. Use the right gloves - it dissolves neoprene and some other rubbers.
(Electrical)
19 Sep 18 16:47Mint -The MSDS doesn't suggest it's as horrible as some of the chlorinated halogen solvents of old. Interlux might not exactly drinking quality, but the like of methylene chloride dissolves epoxy...
(Mechanical)
19 Sep 18 17:14Ah, I was thinking of a different nasty product.
(Aeronautics)
19 Sep 18 22:24Keith,Are you in northern or southern Ca. I am in southern Ca. If you are not too far away I can come up, scarf joint the front of your panels, do a glass repair then re gelcoat and sand out the repair, to where you cannot even see the joint. Of course you panels will look funny if you have a regular joint except for one.B.E.
You are judged not by what you know, but by what you can do.
(Electrical)
(OP)
20 Sep 18 07:49Thanks so much everyone for the knowledge passed around here. Fabulous stuff!Hutz; It's at a horrid working height for me and pretty much not visible. Just below-the-knee height. Can't lay down to work on it. Can't sit down to work on it. Can't bend over to address it. Basically have to hold yourself up with one hand and work with the other. NASTY. So I think I'm going to go forversesI'll clean off the mold release the best I can with something appropriate.Pack the gap with foam-backer.5200 just enough to glue and seal the foam against water splashes to prevent a thick curing cross-sectionLet that sit for a week so the single part adhesive can breath to harden in a thin layer (Thanks Compositepro)Then Silicone forward the remaining 1/8" keeping it a bit behind the face to further keep it from view.That's the plan unless anyone here is violently apposed and cursing my stupidity under their breath.B.E. That is exceedingly generous of you to offer! I'm honored.I'd also take you up on that and make it worth your while if I wasn't inCA (Santa Cruz - well central CA).
Keith Cress
kcress - http://www.flaminsystems.com
(Electrical)
20 Sep 18 12:17There's really no point in using the 5200 if you're going to put Silicone over top of it. Just stuff it and caulk it.
Latex caulking can be smoothed over with a wet rag. Just saying.
(Mechanical)
20 Sep 18 13:48And silicone w/ a wet finger :)
The problem with sloppy work is that the supply FAR EXCEEDS the demand
(Electrical)
20 Sep 18 16:07That gap is awfully wide to expect to get it smooth with a single pass of a finger and with multiple passes it's hard to be smooth at all, at least from my experience.
(Mechanical)
20 Sep 18 16:48Spackle and a knockdown texture?
(Aeronautics)
20 Sep 18 16:49Keith,If you are going to go with Caulking the joint, Take masking tape and apply to either side of the joint about a 1/16" back from the edge. Put your backing rod in place. Then obtain a disposable putty knife just wider than the widest part of the gap. Use a caulking gun and cartridge , don't use a roll up tube, you will not have enough control. Pump your Caulk ( 5200 or whatever.) into the joint quickly , then within 3 minutes take the putty knife and starting at the narrow end make one sweep to the wider end. you get one shot at this , do not go back. Remove the excess at the end of the sweep. pull the masking tape while the putty is wet, again going from narrow to wide end. if yo wait too long the material will string. Good luck. 3M 5200 or most of the other moisture cured Polyurethane caulks take about 2 hours to skin over and 5 days to get a solid full cure.B.E.
You are judged not by what you know, but by what you can do.
(Mechanical)
20 Sep 18 17:46No reason to cover 5200 with silicone, and it may even by a bad idea.
5200 will do fine as a top coat.
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Usually the production time can be shortened by utilizing extra molds for an additional cost, however lead times are not guaranteed without special pricing, and may vary depending on current work schedule. Please check with someone in our sales department for possible availability.
Please be advised that custom architectural fiberglass is a long lead item, and should be ordered as a priority.
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