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

[1985 Century Mustang]

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]

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]

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.

 

[Chris1956]

Sand it anyway to get a "tooth" for the new resin to grab onto.

 

[Scott Danforth]

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

still need to grind

there is no escaping grinding

 

[1985 Century Mustang]

Is sanding ok, I don't have a grinder. I have an orbital sander. And if so what grit should I use.

 

[JASinIL2006]

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]

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]

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.

 

[Scott Danforth]

24 or 36 grit for material removal. 40 or 60 grit for between layer prep. 80 grit for gel coat prep

 

[Chris1956]

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..