Fiberglass help; getting rid of the grain in the cloth?

[BigB9000]

I have been working on a center console for my boat. This is my first attempt... so its obviously not perfect.

It was made using mostly 1/2" exterior AB sanded ply. Except for the front/helm/controls, thats 3/4" exterior cheap stuff.


Here is my sketch of how I wanted it about, excuse the quality please:

And here is what came out:

So I got some 4oz cloth and started glassing it.
Im not using epoxy, Im using the standard home depot poly stuff.
I brush a layer of resin down, then cloth, then another coat or resin. Problem is you can still feel and see the grain of the cloth! making it look not fantastic, and not having that nice smooth glass look

Am I doing something wrong?
Should I sand and lay another coat of just resin down?

 

[ondarvr]

Re: Fiberglass help; getting rid of the grain in the cloth?

That smooth finish is a mold surface, it doesn't happen on it's own with the method you're using. Wet out the wood and at least let the resin start to get hard before applying the glass and more resin. After it get's hard brush a couple more coats of resin or gel coat on it and then sand it down. Fairing putty or filled resin will sand easier than straight resin, it takes a bit of work to get it looking smooth.

 

[CarTuner]

Re: Fiberglass help; getting rid of the grain in the cloth?

You should also use a router to round over all of the corners/edges of the console. This will help the cloth go around the edge, and also help prevent you sanding through.

 

[kaferhaus]

Re: Fiberglass help; getting rid of the grain in the cloth?

You should also use a router to round over all of the corners/edges of the console. This will help the cloth go around the edge, and also help prevent you sanding through.

Yep.... and I would have just used the ply as a "mold" which would have reduced the wieght enormously.

You'll have to make up some "fairing compound" and with a lot of sanding, fairing, sanding and more sanding you'll eventually get it smooth.

I've built several boats (as "therapy") and all turned out very nice but I built one off molds for most everything to reduce weight and the amount of fairing that would be required.

Also, never let anyone lead you to believe that you can build something cheaper than you can buy it IF you look hard enough. Unless your time is worth absolutely nothing!

 

[erikgreen]

Re: Fiberglass help; getting rid of the grain in the cloth?

I have been working on a center console for my boat. This is my first attempt... so its obviously not perfect.

[...deletions...]

It was made using mostly 1/2" exterior AB sanded ply. Except for the front/helm/controls, thats 3/4" exterior cheap stuff.



Am I doing something wrong?
Should I sand and lay another coat of just resin down?

You're doing great. I personally have built stuff like this, and it works well. The exterior ply is just fine if you're covering the whole thing with resin.

The mold technique people mention works well, but it's a lot more time consuming than what you did. Basically you can make a negative impression of the various sides of the console, then pull panels off it and glass them together at the edges to form the actual item entirely out of fiberglass. You'd get a smooth surface, and it'd be light and fairly strong. But I'd bet the ply box is stiffer and stronger, the weight isn't a big deal for what you're doing.

To answer your actual question: When you build something like this, or any composite panel where you don't want the weave of the glass to form your surface, there are a few options:

* First, you can use a surfacing veil as your last glass layer. Basically this is a thin type of mat that's designed to prevent the weave from showing like you are seeing (called print-through). Alternatively you can use a lightweight plain chopped strand mat, that'll give you a more random pattern that might look better.

* You can fill the weave. This is the simplest thing to do. As you mention, you can add resin, but that can look like you've just overdone the resin, and it can run and drip on vertical surfaces. So you thicken it... the usual mix I use is wood flour with some cabosil (fumed sillica) but I've also used the west system fairing compound, or just plain glass bubbles. You just need to put a skim of them on with a scraper, don't expect the cloth to completely disappear in one coat, that'd be too much filler. Fill the weave and then paint with a high build primer.

* You can still mold the surface.... make a mold out of whatever, basically a flat panel with the texture you want in plastic or something you can wax, then use gelcoat or an epoxy paste mix and fill the mold, then clamp/tape it in place on the finished console panel. Wipe away excess and wait for it to harden, then remove the mold and trim it. This is hard to do neatly, but it can produce any pattern you can find, including anti-skid, or any existing glass pattern on your boat.

Erik