Fiberglass layup timing

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rbecker08
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Fiberglass layup timing

Post by rbecker08 » Mon Dec 02, 2019 12:26 pm

Sorry for a bunch of posts today just trying to sprint on construction before I head out for the holidays. I know there is no perfect answer but how much time ballpark do I have to lay multiple layers of glass on top of each other. It should be about 60 degrees at application with slow hardener. Hoping to glass the bottom of the fs17 in one go to cut out sanding and get this thing wrapped up fir a spring splash. I just don't know at which point does it become unworkable and you have to stop let it cure and sand. Thanks



fallguy1000
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Re: Fiberglass layup timing

Post by fallguy1000 » Mon Dec 02, 2019 2:24 pm

rbecker08 wrote:
Mon Dec 02, 2019 12:26 pm
Sorry for a bunch of posts today just trying to sprint on construction before I head out for the holidays. I know there is no perfect answer but how much time ballpark do I have to lay multiple layers of glass on top of each other. It should be about 60 degrees at application with slow hardener. Hoping to glass the bottom of the fs17 in one go to cut out sanding and get this thing wrapped up fir a spring splash. I just don't know at which point does it become unworkable and you have to stop let it cure and sand. Thanks
The challenges are thickness and exotherm and access.

First, you can't work wet on wet if you need to stand on wet glass.

Second, a very thick layup will heat.

Otherwise, if you avoid working in a high heat environment and you have access; you can keep working.

A few tips..

mark reference lines on your glass and/or hull; you want to avoid large moves of wet glass, it is easy to get the lengths wrong, so if you have a 20' piece of glass, a mark on the hull or last layer of glass every 5' will help you make sure you have the stretch right

wetout the last layer with fresh epoxy before you roll out the next glass, that way if the last layer is tacky; you can still move the top layer, I like to make separate batches and I like to apply 40% of the total epoxy to the prior layer with a paint roller before I roll the glass
My boat build is here -------->

viewtopic.php?f=12&t=62495

rbecker08
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Re: Fiberglass layup timing

Post by rbecker08 » Mon Dec 02, 2019 2:33 pm

fallguy1000 wrote:
Mon Dec 02, 2019 2:24 pm
rbecker08 wrote:
Mon Dec 02, 2019 12:26 pm
Sorry for a bunch of posts today just trying to sprint on construction before I head out for the holidays. I know there is no perfect answer but how much time ballpark do I have to lay multiple layers of glass on top of each other. It should be about 60 degrees at application with slow hardener. Hoping to glass the bottom of the fs17 in one go to cut out sanding and get this thing wrapped up fir a spring splash. I just don't know at which point does it become unworkable and you have to stop let it cure and sand. Thanks
The challenges are thickness and exotherm and access.

First, you can't work wet on wet if you need to stand on wet glass.

Second, a very thick layup will heat.

Otherwise, if you avoid working in a high heat environment and you have access; you can keep working.

A few tips..

mark reference lines on your glass and/or hull; you want to avoid large moves of wet glass, it is easy to get the lengths wrong, so if you have a 20' piece of glass, a mark on the hull or last layer of glass every 5' will help you make sure you have the stretch right

wetout the last layer with fresh epoxy before you roll out the next glass, that way if the last layer is tacky; you can still move the top layer, I like to make separate batches and I like to apply 40% of the total epoxy to the prior layer with a paint roller before I roll the glass
Thank you for the time to type that out....I think I am okay except the last layer of cloth, might be a judgement call there. May do this at night too to keep the temp down should be 56 degrees and then just let it sit for a few days.

fallguy1000
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Re: Fiberglass layup timing

Post by fallguy1000 » Mon Dec 02, 2019 3:07 pm

rbecker08 wrote:
Mon Dec 02, 2019 2:33 pm
fallguy1000 wrote:
Mon Dec 02, 2019 2:24 pm
rbecker08 wrote:
Mon Dec 02, 2019 12:26 pm
Sorry for a bunch of posts today just trying to sprint on construction before I head out for the holidays. I know there is no perfect answer but how much time ballpark do I have to lay multiple layers of glass on top of each other. It should be about 60 degrees at application with slow hardener. Hoping to glass the bottom of the fs17 in one go to cut out sanding and get this thing wrapped up fir a spring splash. I just don't know at which point does it become unworkable and you have to stop let it cure and sand. Thanks
The challenges are thickness and exotherm and access.

First, you can't work wet on wet if you need to stand on wet glass.

Second, a very thick layup will heat.

Otherwise, if you avoid working in a high heat environment and you have access; you can keep working.

A few tips..

mark reference lines on your glass and/or hull; you want to avoid large moves of wet glass, it is easy to get the lengths wrong, so if you have a 20' piece of glass, a mark on the hull or last layer of glass every 5' will help you make sure you have the stretch right

wetout the last layer with fresh epoxy before you roll out the next glass, that way if the last layer is tacky; you can still move the top layer, I like to make separate batches and I like to apply 40% of the total epoxy to the prior layer with a paint roller before I roll the glass
Thank you for the time to type that out....I think I am okay except the last layer of cloth, might be a judgement call there. May do this at night too to keep the temp down should be 56 degrees and then just let it sit for a few days.
It will cure poorly at 56 degrees or even 60 degrees. You might want to add some heat while you are around the boat for a few hours. You may also experience blushing. Check for a greasy feeling and if so, it must be washed with warm soap and water. Also, if you try to sand and experience a lot of corning; you need to cure longer or warmer.
My boat build is here -------->

viewtopic.php?f=12&t=62495

joe2700
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Re: Fiberglass layup timing

Post by joe2700 » Mon Dec 02, 2019 3:15 pm

I don't know what epoxy you are using but you can apply a new layer without sanding for a while after the epoxy is dry to the touch. For silvertip epoxy you have 72 hours. If you are talking about the inside bottom I would wait just long enough between layers that the epoxy is not tacky so you can walk on it without damaging it. Then apply the next layer inside the no sanding window for the epoxy you are using. With slow hardener in 60 degrees you might want some extra heat between layers to speed the process.
https://www.systemthree.com/products/silvertip-laminating-epoxy-resin wrote:Cures quickly to a sandable state (no sanding required between coats when recoating within 72 hours).
Edit: The above will only work if you don't have blush, so if you aren't using a blush free epoxy I would probably let it cure and wash then sand between layers at the temps you are talking about. Fast hardener would be better in those temps because you are very near the minimum tempt for slow.

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Re: Fiberglass layup timing

Post by fallguy1000 » Mon Dec 02, 2019 3:24 pm

joe2700 wrote:
Mon Dec 02, 2019 3:15 pm
I don't know what epoxy you are using but you can apply a new layer without sanding for a while after the epoxy is dry to the touch. For silvertip epoxy you have 72 hours. If you are talking about the inside bottom I would wait just long enough between layers that the epoxy is not tacky so you can walk on it without damaging it. Then apply the next layer inside the no sanding window for the epoxy you are using. With slow hardener in 60 degrees you might want some extra heat between layers to speed the process.
https://www.systemthree.com/products/silvertip-laminating-epoxy-resin wrote:Cures quickly to a sandable state (no sanding required between coats when recoating within 72 hours).
Edit: The above will only work if you don't have blush, so if you aren't using a blush free epoxy I would probably let it cure and wash then sand between layers at the temps you are talking about. Fast hardener would be better in those temps because you are very near the minimum tempt for slow.
Reality always seems to bite me on this 72 hour recoat thing. There is always some areas where it is simply too rough to cover without sanding when you wait that long. Perhaps others are willing to allow air in the laminate. I have rarely been able to utilize the 72 hour recoat window. Perhaps the time when this mostly applies is for neatcoating.
My boat build is here -------->

viewtopic.php?f=12&t=62495

rbecker08
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Re: Fiberglass layup timing

Post by rbecker08 » Mon Dec 02, 2019 5:19 pm

The 72 hour overcoat is a great thing to learn, I didn't know it before today. Most of the areas this would effect are in the bildge or under casting decks. I am not trying for air bubbles but drilling and filling here wouldn't be the end of the world and may help me get on the water quicker. Jaysen is helping me put my inner perfectionalist in a box in my other question from today, this continues his work lol.
Thanks for the info.

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Re: Fiberglass layup timing

Post by joe2700 » Mon Dec 02, 2019 6:02 pm

fallguy1000 wrote:
Mon Dec 02, 2019 3:24 pm
Reality always seems to bite me on this 72 hour recoat thing. There is always some areas where it is simply too rough to cover without sanding when you wait that long. Perhaps others are willing to allow air in the laminate. I have rarely been able to utilize the 72 hour recoat window. Perhaps the time when this mostly applies is for neatcoating.
I have certainly experienced rough areas. I will sand high spots or put a smear of ez fillet in low spots before the next layer goes on. My preference is to work wet on wet, just keep adding layers until done if there's time. It's what I did on the outside, but on the inside wasn't possible since I couldn't walk around on the wet glass. Guess I need one of those harnesses that suspends you just over the hull like the fancy builders use :D

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Re: Fiberglass layup timing

Post by Netpackrat » Mon Dec 02, 2019 6:38 pm

rbecker08 wrote:
Mon Dec 02, 2019 5:19 pm
The 72 hour overcoat is a great thing to learn, I didn't know it before today.
I think this only applies if you are using Silvertip epoxy.

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Re: Fiberglass layup timing

Post by fallguy1000 » Mon Dec 02, 2019 8:50 pm

Netpackrat wrote:
Mon Dec 02, 2019 6:38 pm
rbecker08 wrote:
Mon Dec 02, 2019 5:19 pm
The 72 hour overcoat is a great thing to learn, I didn't know it before today.
I think this only applies if you are using Silvertip epoxy.
Yes. Recoat windows are manufacturer specified per epoxy.
My boat build is here -------->

viewtopic.php?f=12&t=62495

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