Question/Advice: Fiberglass over old Fiberglass In Bilge Area.

1985 Century Mustang

Petty Officer 1st Class
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Mar 9, 2023
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I need to Fiberglass over old Fiberglass in the Bilge Area, because it's slightly cracked and I need to address that.

Question- Can this be done, and If so, do I acetone/clean the area, do a first coat of resin and then put on the fiberglass?
 

todhunter

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Sep 15, 2020
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Yes it can be done.

First you need to grind away all the loose / bad fiberglass. If you expose any rotten wood, you'll need to deal with that before putting new glass down. For grinding, I recommend 36-grit flap discs on an angle grinder. Besides removing old / bad glass, it also works great for roughing up the surrounding areas for the proper mechanical bond when you go to lay new glass.

After all the grinding is done, then you'll acetone wipe, roll out resin, lay your cloth, then wet out the cloth.

Post some pics and some of the forum members may be able to give better advice.
 

1985 Century Mustang

Petty Officer 1st Class
Joined
Mar 9, 2023
Messages
341
Yes it can be done.

First you need to grind away all the loose / bad fiberglass. If you expose any rotten wood, you'll need to deal with that before putting new glass down. For grinding, I recommend 36-grit flap discs on an angle grinder. Besides removing old / bad glass, it also works great for roughing up the surrounding areas for the proper mechanical bond when you go to lay new glass.

After all the grinding is done, then you'll acetone wipe, roll out resin, lay your cloth, then wet out the cloth.

Post some pics and some of the forum members may be able to give better advice.

Thanks, There's no broken fiberglass, just slight cracks.
 

JASinIL2006

Vice Admiral
Joined
Feb 10, 2012
Messages
5,575
You can sand, but it will take a long time... I'd start with 40 or 60 grit paper on an orbital sander.

You can get a 4.5" corded grinder from Harbor Freight for about $15. That would save you a whole lot of time...
 

todhunter

Canoeist
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Sep 15, 2020
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Is sanding ok, I don't have a grinder. I have an orbital sander. And if so what grit should I use.
THIS $34 grinder got me through my entire restoration, and despite how much fiberglass dust it ingested, it's still kicking. THIS $19 box of 40-grit flap discs is what I used. Don't forget the PPE you'll need - a MASK for $17 and FILTERS for $25.

So, for $100 you can have the tools and and PPE to do the job right. Or, if you already have the PPE, you're looking at roughly $60.
 

1985 Century Mustang

Petty Officer 1st Class
Joined
Mar 9, 2023
Messages
341
I only have to do a very small section, I think I'll use my orbital sander. Also can I use 3m 5200 and seal the small cracks....That stuff is amazing.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,268
Don't put anything under the fiberglass. The new resin and cloth will seal just fine. The existing fiberglass just needs to be clean and a bit rough, to bond well with the new resin/glass..
 
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