gelcoat chips and deep scratches - repair...

[niccapotamus]

I kind of know the answer but I'm just after a bit of reassurance before I take the wet and dry to the boat!

Old boat (30 years) with a number of chips and scratches in the cockpit mainly (and the bow!) which need to be repaired. According to my book I just buy some gelcoat filler from the chandler, maybe try to colour match, and then fill, and sand back, finishing with cutting paste and polish

so it is OK to sand Gelcoat then?

Just reassure me please before I go and do it in the new year as obv i'll be sanding not only the repair but the surrounding gelcoat as well

plus any valuable tips?

ta muchly

 

[richardabeattie]

Yes - perfectly OK if you use reasonably fine sandpaper and go gently. You only need to key the actual area to be repaired. Why do you think you need to sand areas which are not damaged?

 

[laika]

Bevel the edges of the chips with a dremel if you have one. I use one of those cone shaped grindy head things.
Don't be tempted to carry on using the filler after it starts to dry: you'll only have to dig it out and start again. You don't have that much time to work with it on a hot summer's day
If the gelcoat is basically white, consider ignoring the advice to colour match. It's incredibly hard to get exactly the right shade. I've invariably gone too off-white when I've tried. Just go with the basic white and it'll be invisible within a few months.
Yes you can (and should) sand it. I take any peaks off with the dremel. I then have my favourite little block of wood about 3cmx3cmx2cm which I use to back the paper, going 400, 800, 1200.
EDIT: should have said: wet&dry used wet!!
Don't be upset if you get the occasional bubble leaving a little depression: I normally let it dry then go round again dabbing in a bit of gelcoat on with the end of a match and sanding it back down.

 

[niccapotamus]

Yes - perfectly OK if you use reasonably fine sandpaper and go gently. You only need to key the actual area to be repaired. Why do you think you need to sand areas which are not damaged?

I wasn't going to focus on the undamaged areas but there is bound to be some collateral sanding to areas around the damage

 

[gjgm]

Yep, you need to open the cracks so there is enough surface area for the gel to bond; if you don't have the mentioned dremmel, a sharp screwdriver or an old fashioned tin opener (the one that would make a triangular hole). You don't need to create major damage, but it isn't going to bond in a tiny crack either! Sand the surrounding area with say 1200 wet and dry;dont get too keen on this, but the idea is to "blend" the dirty old gel and towards brighter clean gel where the crack is. Just put some gel paste in and smooth as well as you can. Start with 320, then 600 and finish with 1200 grit wet and dry (use wet!) A bit of polish and wax .
Nothing wrong with having a go with some gel and pigments (and hardener!) but it is a bit more work. It needs to be warm so either Spring or you are going to need to warm the area.

 

[lw395]

I wasn't going to focus on the undamaged areas but there is bound to be some collateral sanding to areas around the damage

Mask around the damage until you get to fine sanding/cutting.
If you fill up to the top of a strip of parcel tape either side of the damage, there can be very little sanding to do.

 

[nigelmercier]

Mask around the damage until you get to fine sanding/cutting.
If you fill up to the top of a strip of parcel tape either side of the damage, there can be very little sanding to do.

I've used masking tape, but parcel tape is an even better idea.

 

[charles_reed]

I kind of know the answer but I'm just after a bit of reassurance before I take the wet and dry to the boat!

Old boat (30 years) with a number of chips and scratches in the cockpit mainly (and the bow!) which need to be repaired. According to my book I just buy some gelcoat filler from the chandler, maybe try to colour match, and then fill, and sand back, finishing with cutting paste and polish

so it is OK to sand Gelcoat then?

Just reassure me please before I go and do it in the new year as obv i'll be sanding not only the repair but the surrounding gelcoat as well

plus any valuable tips?

ta muchly

Don't use sandpaper - get some wet&dry and finish off with 1200 grit.

 

[laika]

Don't use sandpaper - get some wet&dry and finish off with 1200 grit.

Yes: have edited my earlier post to say wet and dry used wet.

 

[niccapotamus]

thanks very much!

reassured