Concealing fiberglass flaws

[Haraald]

I'm building a custom bathroom and sleeping pod in the bed of my truck that's plywood with fiberglassed seams so it's all smooth and seamless like a shower stall. Problem is I'm an amateur and after a ton of sanding (and an infected eyelid because of the dust), it's still a bit bumpy with exposed cloth here and there. Is there a way to cover the flaws up so when I paint the whole thing white it looks smooth and not like a theme park cave? West Marine sells 'build up' marine primer that I was going to apply; maybe 3 coats, but it's expensive.

Thanks!

 

[joelbert]

At the end of the day, why does it matter that much?

Once it's waterproof and can be just wiped down. It's probably just you and your SO, spend more time/$ on camping and just let it go as the best you could do... I don't think anyone is going to critique it or tell you it could be better.

My .02$

 

[Stumpalump]

On boats smooth glass that comes out of a mold has layers of thick smooth gel coat sprayed first. Areas where where bulk heads,engine stringers or cabinets are attached to the glass hull it looks like yours. Grind it smooth as you can then coat the exposed glass mat with a resin coat. Paint it with bilge paint. It will be bumpy compaired to your home tub but so are million dollar yachts that have glassed in areas. The smooth you see was touching the mold not the hand laid glass and resin. You can also speckle paint it if you want it invisable.

 

[Ducky's Dad]

Go to the Jamestown Distributors web site and watch their boat building/repair videos. Best solution is probably to mix a thin batch of polyester filler (like Bondo mixed with a little laminating resin and appropriate catalysts) and smooth the area with a plastic spreader. Don't overwork the surface. Sand lightly and do it again. Sand lightly, etc. When it is smooth enough to suit you, apply the final finish, whether it's paint, epoxy, or finishing resin. Jamestown's tech support guys are pretty helpful.

 

[fluffyprinceton]

" Is there a way to cover the flaws up so when I paint the whole thing white it looks smooth and not like a theme park cave? West Marine sells 'build up' marine primer that I was going to apply; maybe 3 coats, but it's expensive."

Fill with rough areas with bondo, sand 90% of it away repeat till you're happy or disgusted. There's no easy way & 3 layers of primer won't help much at all.

The "easiest" way is to use epoxy based "fairing filler" as it is much easier to apply & sand than bondo. I've done it on large boats many times and it's not a big deal if you are used to it...The skills are all basic and with enough effort a very nice finish will result. The 2 part "ready mix" fairing fillers are excellent & expensive & mixing your own is cheaper but requires study.

The advice to leave it rough because it doesn't functionally matter is partially correct - it will be somewhat harder to clean...but for some of us "function" includes an attractive finish.Moe

X2 on Ducky's Jamestown suggestion.

 

[Ducky's Dad]

Epoxy filler is better than polyester, but is much less forgiving regarding temperature and catalyst ratio. Epoxy is also more expensive. Polyester is pretty much idiot proof, so is beginner-friendly. I just repaired a bunch of fiberglass in-ground duck blinds and I used polyester resins and fillers because ambient temps ranged from 65 to 105 and I did not want to screw around with different catalysts and precise metering to match the conditions.

 

[jim lee]

Oh lord!

Ok, your in Washington. You are sitting in boat building Mecca. Take advantage of your local resources. You have some of the best here!

First here's a good place to get your supplies : fisheriessupply <- wasn't allowed to post links but its close.

Here is another, AND they can give advice : fiberglasssupply <- wasn't allowed to post links but its close.

As for waterproof faring, if you started with polyester or vinyl ester you want to use 3M Marine Premium Filler. Its like Bondo but permanent and waterproof. Bondo will suck up water and die after awhile.

IF you started with expoxy, you need to stay with epoxy. You can make fine faring compounds with epoxy they are just harder to work with. At the last minute, just before epoxy sets up, it goes through a runny stage causing you're perfect fillets to sag.

Don't start randomly mixing chemical systems. Down that path madness lurks. Most of these chemicals systems don't get along.

Are you trying to protect from water spraying on the inside or from water getting in from the outside? From the pix I'm going to guess inside.

If I had to seal up the inside using polyester? I'd..

Paint everything with a coat of the resin to seal up the wood and give something for the rest of my work to attach to.
Sweep the radiuses with the 3M putty. (Assuming you don't need to tab the seams. Do you need to tab the seams?)
Do a rough sanding with the longest sanding blocks possible. Maybe to 80 or 60 grit? Certainly no finer. This is rough shaping.
Re-coat everything with resin one last time.
Now skincoat the entire inner surface with.. 1oz mat. (Remember to get ALL the air out!)
Lightly sand the prickles off once this kicks off. You should be able to run your hands over everything without getting stuck or cut.
Get a long flexible plastic squeegee and coat the inside with the fairing putty. This will be a thin layer.
Sand smooth to 80 grit only.
Take your gelcoat, add wax (surfacing agent) and spray it in there. (Good luck getting that step to work well.)
When it kicks off, your done!

If everything is done right you will end up with a smooth Matt finish. This is used a lot for racing sailboats to finish off the inside of the cabins. Racing sailboats need VERY light interiors that can take a beating.

Hope this helps!

-jim lee

 

[Haraald]

Thanks jim, I already finished the project with interlux Brightside... I just didn't have the time or equipment to get a smooth finish. It is glossy and white though. There's no way for an amateur to get a smooth resilient finish without weeks of labor

 

[Coachgeo]

For next project...... forget smooth. Go with a purpose textured look. Coat it with a form of krinkle paint or better yet truck bed liner stuff.

 

[doug720]

There are ways, several in fact that are not too bad to do.

As mentioned - resin - Look at surf boards. Coat, sand polish - No Finish on a surfboard

Fair with filler - you can buy "glass bubbles/beads" to make resin into filler that sands smooth fairly easy - Paint to finish

For fillets and fairing you can buy "Kitty Hair" - resin with fiberglass strands that you add catalyst to - Harder to sand - Paint to finish


Apply gel coat with brush or spray with a sealer over it so it will cure. Then sand and polish - No paint required

 

[rayra]

...There's no way for an amateur to get a smooth resilient finish without weeks of labor

The hell there isn't. It's basic bodyworking skills. Put a couple coats of clear resin on, lightly sanding before each. That will rebuild what OUGHT to be there. When you sand, do NOT sand until you are tearing up the fabric. You have to build OUT with fiberglass work and metal / bondo body repair, you can't tear in as with woodworking.

Go watch some basic bodyworking videos on finishing bondo, it's much the same techniques.

You have to add skim coats of resin or bondo putty glaze etc. You have to build it up, to cover the deficiencies in the initial fiberglass work.

Just the basic fact that you are sanding down into the fiberglass matting and NOT doing so as a prep for laying more glass tells me you don't know very much about the process. There's a ****-ton of youtube videos that would be very useful to you, go watch some.

 

[Ducky's Dad]

There's no way for an amateur to get a smooth resilient finish without weeks of labor

It's actually pretty simple once you figure it out. Fiberglass is very forgiving, especially with polyester resins and fillers. You don't even need to use a gel coat, just get it smooth and hit it with a coat of finishing resin. I taught myself 50 years ago repairing surfboards, and nothing has changed except the advent of epoxies. And carbon fiber.

 

[Haraald]

Part of the problem is this is all taking place in the canopy of truck- I'm in very close contact with the resins and sanding, poor ventilation, and there's tons of weird angles and crevices not to mention incredibly tight quarters and it's very hot... it's not like doing a surfboard out in the yard. My skin burns a lot when resin gets in contact with it and I've spent $500+ on an infected eyelid at my doc's office after a week of sanding. For the time being, I'm done with the f-ing fiberglass Should I have spent hours researching how to do it better and buy a whole suit with respirator etc? Of course lol

Is there anything similar to mudding drywall I could do that could go on top? I'm pretty good with a drywall blade and if the material is that same consistency I could do a decent job. I just can't do anymore liquid fiberglass now though. It really does look like shiny theme park cave right now as you can see below, and I wish it was smoother. If someone does have a recommendation please link me to a specific product, the guys at West Marine don't know anything about their inventory and I'm not good with searching online.

 

[Ducky's Dad]

Did you call Jamestown Distributors or look at any of the instructional videos on their site? It's all there, just waiting for you. Everything from how to repair a cracked hull to building a tank fairing for your motorcycle.

I think you complicated your life with the Interlux. Good stuff, but it's going to be hard to stick anything to it without a lot of prep.

 

[jim lee]

Did you glass after you installed equipment?

-jim lee