Repairing scratches in gelcoat

[Tafflad]

I have recently bought a 12 month old Monterey, and it is almost mint (12 Hrs on engine)
There are a however a couple horizontal scratches just off the keel line at the front of he hull ... probably trailering activity.

These are 2mm deep at deepest tapering out form that so in general less than that total length of each being about 200mm long.
With a few smaller shallower ones.

Dealer advised they would polish out .. but has also sent me a new pack of Plastic Padding Gelcoat filler.
I mixed a small pea sized blob ... and colour match is pretty good.

Be interested in tips on best way of how to deal with scratches and whether I should try and fill 'all' of them or polish some out.

Not sure how well this pic will show it, the black scuff is the keel line, and that just wiped off easily, looked like rubber off a roller.



http://i771.photobucket.com/albums/xx351/Tafflad/boats%20n%20things/scratch_zps54c5b122.jpg

 

[Woodonglass]

Re: Repairing scratches in gelcoat

YD is one of our gelcoat experts. I suspect he'll be along soon to help you out. IMHO some of those could be buffed out, but I'd prolly try to fill some of the deeper ones, especially if the filler they sent is a good match.

 

[Tafflad]

Re: Repairing scratches in gelcoat

YD is one of our gelcoat experts. .

Happily wait for YD

I have done some fibreglass work before - glassing in laminated supports for a Tower .. and even a hole through the gelcoat to fibreglass in a previous boat ......... just want to get best techniques ofrm those that know on dealing with the scratches.
i did search here first ... so have seen the ATP lesson I & II

 

[Yacht Dr.]

Re: Repairing scratches in gelcoat

Looks like you can sand and buff them out.

Take a marker into the scratches .. then sand with some 320 up to 600 grit. Buff that and see what you have.

Remember though .. the more you sand the more unfair it becomes.

You might not see the scratches .. but you will see the dimples from where you sanded on.

You could sand out the minor scratches and then fill the deeper ones with your patch paste .. but those fills will eventually pop without doing some spray over them.

So sand and buff .. or sand/buff what you can and fill those deeper ones with your gel paste.

Go a step further and spot spray those repairs .. then sand and buff your spray spots.

YD.

 

[Tafflad]

Re: Repairing scratches in gelcoat

"spot spray" ...can you explain with what.
You mention filler will pop ? Why is that, I thought epoxy became 'one' with the layup.

I have some West System epoxy as well, but this is clear not white.

 

[Woodonglass]

Re: Repairing scratches in gelcoat

Gel coat is not epoxy and the repair kit they sent you is not epoxy. Gelcoat is a polyester based substance. I'm pretty sure he's referring to filling the deeper ones, sanding fair, then spraying thinned gelcoat over all of it with a PreVal spray kit. Then Buffing it all out. The hull will flex and the small repairs will pop since they need a bigger surface area to "Bite" and adhere well to the hull. Spraying some gel over a wider surface will give better "Grip". Well, I guess I've put words in YD's mouth so, I'll stop and let him tell you if that's what he meant.

 

[Tafflad]

Re: Repairing scratches in gelcoat

Gel coat is not epoxy and the repair kit they sent you is not epoxy. Gelcoat is a polyester based substance. I'm pretty sure he's referring to filling the deeper ones, sanding fair, then spraying thinned gelcoat over all of it with a PreVal spray kit. Then Buffing it all out. The hull will flex and the small repairs will pop since they need a bigger surface area to "Bite" and adhere well to the hull. Spraying some gel over a wider surface will give better "Grip". Well, I guess I've put words in YD's mouth so, I'll stop and let him tell you if that's what he meant.

The product I was given is called "GelCoat Filler" which would suggest is is designed for filling Gel Coat ..? or am I mising something

On this link Plastic Padding Gel Coat Filler | Bosun Bobs.com

They show the product and if you scroll down they also show a Gelcoat Epoxy as a separate item (which I don't have)

I don't have spray on Gelcoat,

 

[Woodonglass]

Re: Repairing scratches in gelcoat

I understand that all they sent you was the filler. What YD is saying, I THINK, is to use what they sent you to fill the deeper scratches and then buy some regular gelcoat to spray over all of the repairs using the PreVal sprayer. He's a PRO and that's how he would do it in his shop. Again Gelcoat is NOT an epoxy based product. If yours is the Epoxy filler, I believe it's the wrong one to use. Your boat is coated with Gelcoat, a poly resin based product, and Not epoxy. I could be wrong, but I don't think so. YD will have the definitive answer, so I'll quit and let him finish.

 

[Tafflad]

Re: Repairing scratches in gelcoat

I understand that all they sent you was the filler. .

They sent me the GelCoat Filler ...(2 part pack) they advise this is what they use to repair minor scratches ... no mention of gelcoat spray

 

[Woodonglass]

Re: Repairing scratches in gelcoat

Yep and like YD says, when filling small and not so deep scratches and gouges, if you do it the way they say, the Filler will POP loose sooner than later. His way will make it permanent. Your boat...Your Choice.

 

[Tafflad]

Re: Repairing scratches in gelcoat

Yep and like YD says, when filling small and not so deep scratches and gouges, if you do it the way they say, the Filler will POP loose sooner than later. His way will make it permanent. Your boat...Your Choice.

Maybe I am missing the point (or something) ...
If I use 2 part Gelcoat filler then flexing of the hull will cause loss of adhesion and filler will pop ?

Spraying Gelcoat over this will stop this happening ? .... how ?

If the filler has lost adhesion how can a couple of microns of gelcoat hold it in place ... especially as you will have sanded down and polished it back ? flexing is still happening ?


This is a totally new thing to me (hence the Q's)

When I did some small scratch repairs some years ago .. I simply cleaned with acetone, mixed up Gelcoat with catalyst, painted it in, and then sanded it back. ( No spraying )


Why I want to understand this .... as if I have to overspray with Gelcoat what would be the point in using the filler ... I might as well fill scratches with Gelcoat ?

 

[Yacht Dr.]

Re: Repairing scratches in gelcoat

Thank you Woody for stepping in for me .. my kid got sick and I was kinda .. away ..your suggestions on my part is correct without method.. I will answer ..

Maybe I am missing the point (or something) ...
If I use 2 part Gelcoat filler then flexing of the hull will cause loss of adhesion and filler will pop ?

Its not really a matter of Flexing .. its a matter of H2O that will cause loss of adhesion and fillers.

H2O is a very small molicule that will penitrate a repair done with only gel paste. Look at your repair with a microscope and you will see the edges. Water will get in there no matter.

Spraying Gelcoat over this will stop this happening ? .... how ?

You are in fact Burning the Gel. .. you are encapulating the gel over the repair .. You are making it smaller to leave the H2O from Creeping into your repair. Your just preventing water (H2O) from getting into your 'repair'

If the filler has lost adhesion how can a couple of microns of gelcoat hold it in place ... especially as you will have sanded down and polished it back ? flexing is still happening ?

Its not about flexing .. its about shrinkage ..

This is a totally new thing to me (hence the Q's)

When I did some small scratch repairs some years ago .. I simply cleaned with acetone, mixed up Gelcoat with catalyst, painted it in, and then sanded it back. ( No spraying )


Why I want to understand this .... as if I have to overspray with Gelcoat what would be the point in using the filler ... I might as well fill scratches with Gelcoat ?

There is no reason to fill with anything other then gel paste .. unless its deeper then the surface gel . .then you have to go with somthing a bit more stronger ..

Hope this helps ..

YD.