Fiber glass turned grey

[Vegadank]

Hey
My boat had a lot of crazings so I decided to grind down the gelcoat and do some reinforcement.
But as I got to the top roof allmost all the fiberglass was black/grey coloured.
Some places I managed to get it away by grinding deeper. Others I did some pretty deep cuts and still stayed grey.

What should I do?

[Suijin]

Looks to me like you're still grinding gelcoat. Hard to tell from the photo. And what are you grinding with, a dremel? I would suggest going at it with an 8" soft pad on a grinder/polisher. You'll end up with a much flatter, more even surface which will be easier to repair going forward.

Some boat manufacturers added dyes/colors the layers of their fiberglass layup so they could better see coverage, overlaps, etc. as they were working. That might be what you're seeing if you're actually down to the glass.

Edit: on second look it does look like you're into the glass, or at least the resin.

[hellosailor]

I'm not seeing any black coloring in that photo. "Stuff" often is some kind of gray, because making it white involves adulterating the resin with something expensive like titanium dioxide, and you just don't do that until the final cosmetic top coat.

[Vegadank]

Here is some better pictures. I clearly see the fibers so i should be through the gelcoat.

[Privilege]

It looks normal. Thin fiberglass is reasonably transparent so I think you're just seeing the underlying surface.

[JPA Cate]

Vegadank,

I, too, think you have disappeared the gelcoat. In the thread "Nauticat52 Re-Fit" boat worker extraordinaire "minaret", explains how to re-gelcoat. A CF Google Custom Search under the Search menu should find it for you. There may be more information on the internet about the subject as well. However, over the years, I have learned to trust minaret's info, and other sources are unknown to me.

Ann

[coastalexplorer]

In the boat building trade some custom/limited production mouldings such as decks & cabin tops were made in inexpensive female moulds constructed by building a frame work and covering it in a skin of thin MDF sheet material. Which was sometimes sprayed with a protective coating. or more usually coated with mould release wax.

Obviously the surface finish on the product would not be as good. So it needed to be polished after removal from the Mould.

Thus a common practice was to start the process by spraying the desired colour Gell coat. and then backing that up with a different contrasting colour. Before continuing with the lay up. So that during the polishing process it could be seen if the top coat was getting thin before breaking through. During the late 1960's resin was often supplied grey in colour.

Apart from boat building; GRP was frequently used to coat sun decks on houses. Not such a common practice currently. The most common colour used was grey. The high volume demand for this may have made the product cheaper. How ever I do believe that an old lay up can change colour by water intrusion/damage.

[Vegadank]

Alright then, The boat is from 1970.
So "coastalexplorer" what you say about applying different colours for the different parts. Makes alot of sence, then it looks like it start right after the angel shifting.
Probably just me being nervous.
I will then continue grinding it smooth to make New gelcoat and nothing more fancy.

[boatpoker]

Originally Posted by Vegadank

Alright then, The boat is from 1970.
So "coastalexplorer" what you say about applying different colours for the different parts. Makes alot of sence, then it looks like it start right after the angel shifting.
Probably just me being nervous.
I will then continue grinding it smooth to make New gelcoat and nothing more fancy.

Ok it's tough to tell from the photos but I suspect it's either home built or a low quality production boat as I can see no sign of roving or mat. It looks like it's all chopped mat or maybe even chopper gun.

What say you ?

[Vegadank]

it is a factory build Albin Vega.

[coastalexplorer]

Vegadank,,,I do not understand your line...right after the angel shifting.

The point I was trying to make was; That even when a production hull mould is used. A customer could want a non standard deck and coach roof lay out. So a boat shop not want to turn a client away would produce cheaply built alternative tooling.
It was a pattern makers job to produce a male shape in wood. called a pattern in Foundry work, Circa 1958 these three dimensional shapes were called a Plug in the fibre Glassing trade. Back in those days early 1966 -71 we used a product called Furain. (not sure I recall correct spelling) it was made at the Southampton, Hampshire plant in the UK by the Borden chemical co. (now is a part of Hexion Specialty Chemicals. Possibly bought out by Synthomer) The liquid had a viscosity like water, with a liquid Catylist and was a black as coal. Application was about 15 coats the cured surface was wet sanded though all the grades to 1000 grit and finished with Brasso metal polish and mirror glaze wax. From a plug like this the fiber glass production mould was made. So much for extreme British craftsmanship?
While there I did see Some less in important work was spray coated in a catalyzed polyurethane finish. flat sided products could be made from a female mould built out of "beauty Board' which had a laminated strip core covered in Formica, cellophane membrane protected.

Here in Canada I had to become accustom to less technical methods. The shaped frame with MDF skin being the most common. Quick and very cheap by comparison to make. Being open to other ideas I once built a curved stillage and skinned it with Ply wood, which I contact adhesive gloss Aborite on to. The builders wood yard sell part damaged sheets quite cheaply. and of course the colour does not matter.

The task was to put more curvature on the bottom of a dingy that was too flat. A situation vaguely similar to the coach roof problem Vegadank is taking on. This process I have heard termed as 'shingling". after release agent. Gel coat applied & cured and first two layups are carried out on the curved mould surface and allowed to green cure.
Another wet layup is applied to the bottom of the over turned hull, with sufficient material the fill the anticipated void. before that cures the 'Mould' is turned over and weighted in place.( Plastic milk jugs filled with beach sand are quite adequate) Sort of like putting a saddle on a horse. After curing only the edges need clean up. The main area has a perfect gloss finish as good as the mould surface used.. never have I done this on a cabin coach roof.

Another common practice around here is to lay up on a layup table that is topped with a pane of plate glass. The panels produced are left thin and flexible enough to be bent to a desired shape. and then 'backed up' with additional layup to bond them in place, create structure and to set their shape. Very large Power boat hulls are constructed this way. a bow and stern mould is made and the mid ships filled in With pannels

[Squanderbucks]

The color of the underlying glass is highly variable depending on the production method of the builder and what supplier they happen to be using at that stage of production. Common colors are pink, green, clearish with amber tones.
Spray chopped glass/resin from a chopping gun most always uses a colored catalyst to help see the evenness of application.
There is no real need to totally remove all the gelcoat when doing repairs. It is simply a colored resin of compatible blend. All you need to do is evenly sand out the surface to a clean uniform degree with something like 80 grit.
Wheather going with polyester or epoxy make that decision based on strength needs and cost factors. Small structural repairs with high stress use epoxy. General hull repairs over larger area probably poly or vinyl ester resins.

[Vegadank]

Thank you costalexplorer! Certainly learnd alot about fiber glass production my plan was only to fix the crazings. But as i dig down I saw all this black fiber. I was shure it was soken so just continued grinding trying to find it smooth dry. As I thought was supposed to be yellow, as from my prior boat... But as you and Squanderbucks tell it could be anycolour.
I am not trying to make it higher or anything like that. So think im just gonna fill in some polyester, where i took the most then paint it up white n shiny

[Northbound44]

The black spot we can see throughout the fibreglass look like rotten wood. You should take a reading with a moisture meter or at least use a hammer to see if any d’éliminations. This could be the reason why your boat have a lots of crazing.