Chopstran is clumpy. Is this an issue when putting on the regular fiberglass?

[1985 Century Mustang]

I used chopstran and wet out the area first, then I applied the chopstran and wet that out but it got clumpy and It's almost dried. Should I wait and then try to remove the clumped strands? If so should I lightly sand it down?

In the below photo you'll see some white areas which is marine Epoxy PC11, but the other areas circled in red, you can see the fiberglass clumps.

 

[Bondo]

I used chopstran and wet out the area first, then I applied the chopstran and wet that out but it got clumpy and It's almost dried. Should I wait and then try to remove the clumped strands? If so should I lightly sand it down?

In the below photo you'll see some white areas which is marine Epoxy PC11, but the other areas circled in red, you can see the fiberglass clumps.

Ayuh,..... I always sand between dried layers,....

'n using epoxy, you really don't need chopped strand mat, which is used for a resin rich layer, with polyester resins,....

 

[1985 Century Mustang]

Ayuh,..... I always sand between dried layers,....

'n using epoxy, you really don't need chopped strand mat, which is used for a resin rich layer, with polyester resins,....

I used PC11 to fill small chips and drill holes. I didn't use epoxy on the transom. It was basically bare wood. I just spot treated the areas weeks before doing the polyester resin wet out and chopstran today.

How can I smoothe out the dried clumpy chopstran? Is it normal to have clumping of chopstran?

 

[CClassen]

I used PC11 to fill small chips and drill holes. I didn't use epoxy on the transom. It was basically bare wood. I just spot treated the areas weeks before doing the polyester resin wet out and chopstran today.

How can I smoothe out the dried clumpy chopstran? Is it normal to have clumping of chopstran?

As far a smoothing out the chop strand, you can use a sander or grinder with a flap disc. I like the 40-60 grit range to remove material. The clumpy areas might have had too much resin? I cant say if it’s normal or not, I’m on my first rebuild but haven’t had the problem yet. I am a beginner at best right now. GL tho!

 

[1985 Century Mustang]

As far a smoothing out the chop strand, you can use a sander or grinder with a flap disc. I like the 40-60 grit range to remove material. The clumpy areas might have had too much resin? I cant say if it’s normal or not, I’m on my first rebuild but haven’t had the problem yet. I am a beginner at best right now. GL tho!

Thanks

 

[JASinIL2006]

I’d grind out the clumps and re-glass. I’m not a bug fan if epoxy under the fiberglass, as poly resin doesn’t stick that well to epoxy.

I’d also consider grinding back the gelcoat in areas around your transom core. When you tab in that area, you want the new glass to adhere to the old glass, not to gelcoat. I would suggest grinding back 4-6” around the transom core.

Are you planning to use some kind of fiberglass cloth (e.g., 1708 biaxial or 1700) over the CSM? CSM by itself adds very little strength. It largely is there to help the woven cloth adhere better. The woven stuff is what brings the strength.

 

[1985 Century Mustang]

I’d grind out the clumps and re-glass. I’m not a bug fan if epoxy under the fiberglass, as poly resin doesn’t stick that well to epoxy.

I’d also consider grinding back the gelcoat in areas around your transom core. When you tab in that area, you want the new glass to adhere to the old glass, not to gelcoat. I would suggest grinding back 4-6” around the transom core.

Are you planning to use some kind of fiberglass cloth (e.g., 1708 biaxial or 1700) over the CSM? CSM by itself adds very little strength. It largely is there to help the woven cloth adhere better. The woven stuff is what brings the strength.

Yes I'm doing the 1708 also. In what I have researched, you should do the CSM then the 1708. If i would have known that the CSM was a pain in the ass, I just woulda went with 1708.

 

[1985 Century Mustang]

I could of used Kevlar also.

 

[1985 Century Mustang]

Yeah I'll grind it out or sand it. I may have to cut out a piece thats really protruding outward., and patch it in. Then I'll use the 1708 carefully.

 

[cyclops222]

Clumpy fiberglass can be from the ratios not being correct. If it is mixed to set up faster. By accident. You may have to wait a day or to for it to fully cure and be stiff enough not to clog the grinders. Remember also that some odd ball epoxies harden up. WITH a WAX coating on top of the surface. It must be removed to put any new glass coats on.

 

[froggy1150]

It's best to lay your csm and 1708 at the same time if possible

 

[JASinIL2006]

You don’t need to lay CSM first. That’s why 1708 is nice; it is 1700 biaxial cloth with CSM stitched to it. Just be sure the CSM side is laid against the substrate and the woven side is facing out.

 

[1985 Century Mustang]

You don’t need to lay CSM first. That’s why 1708 is nice; it is 1700 biaxial cloth with CSM stitched to it. Just be sure the CSM side is laid against the substrate and the woven side is facing out.

You live and learn. For some reason I thought you do CSM first and then 1708. Where was my head at. Arghhhh. . CSM is really nasty to work with.. never again. Luckily is was able to smoothe it out. I'll do 1708 tomorrow and I'll be finished. The boat should be in the water by Thursday hopefully. All the tuff work is basically done. Engine, Bell housing, Transom mount and wiring should take me 4 hours tops.

 

[1985 Century Mustang]

I should of wet it out with a mini Roller. I helped my neighbor with his project and the roller worked out way better than a brush. Way less clumps and shredding.

 

[todhunter]

A chip brush has its place (with the bristles cut short and even), but I did 95% of my boat with a 4" mohair roller.

 

[JASinIL2006]

I should of wet it out with a mini Roller. I helped my neighbor with his project and the roller worked out way better than a brush. Way less clumps and shredding.

MIni rollers do work better for wetting out large areas, but even then, you can get clumping when using CSM. It's miserable stuff, IMO.

 

[1985 Century Mustang]

I sanded out the clumps of the CSM today, came out nice. I then applied a layer of 1708 and it covered pretty good for an amateur. I'm starting to see the light at the end of the tunnel.

 

[1985 Century Mustang]

Can I paint the 1708 now, and if so what are the steps and type of paint I can use. I have Topside Paint by Rust-Oleum, will that be ok.