What colour is gel shield & bare gelcoat?

[Tim Good]

So I’ve always wanted to do coppercoat but never had the chance to sand blast off all the old antifoul. However there isn’t much of a layer of antifoul on my boat but there is a bomb hard layer of primer.

Then recently I was walking past a boat in Mylor and ask them what they were doing as it looked like the yard was about to do coppercoat. It looked like my hull, mostly grey but with a few very small bits of green showing through.

They said it had already been sand blasted.

So that made me think the gel shield on my boat is actually grey and I was mistakenly thinking it was the original antifoul primer. This does account for why it’s so god same hard to remove even with a very good scraper!

See pic attached. Red and blue is clearly old antifoul after being jet washed. Is the grey gelshield which was out on by the previous owner about 10 years ago, and then there is a slight bit of green in the odd place which I’m thinking is original gelcoat?

 

[lusitano]

So I’ve always wanted to do coppercoat but never had the chance to sand blast off all the old antifoul. However there isn’t much of a layer of antifoul on my boat but there is a bomb hard layer of primer.

Then recently I was walking past a boat in Mylor and ask them what they were doing as it looked like the yard was about to do coppercoat. It looked like my hull, mostly grey but with a few very small bits of green showing through.

They said it had already been sand blasted.

So that made me think the gel shield on my boat is actually grey and I was mistakenly thinking it was the original antifoul primer. This does account for why it’s so god same hard to remove even with a very good scraper!

See pic attached. Red and blue is clearly old antifoul after being jet washed. Is the grey gelshield which was out on by the previous owner about 10 years ago, and then there is a slight bit of green in the odd place which I’m thinking is original gelcoat?

Think green and grey could both be Gelshield. The application involves a build of alternating colour coats of green and grey

 

[Tim Good]

Think green and grey could both be Gelshield. The application involves a build of alternating colour coats of green and grey

Arr ok that’s interesting.

So if the grey is bloody hard and can only be removed with a sharp scraper, then the chances are that it is in fact gel shield and not very very well adhered antifoul primer from over 8 years ago prior to my ownership of the boat?

 

[snowbird30ds]

The idea of gelshield is to apply alternating colour coats, it's the same stuff but means you can see if it's all covered before the next coat, grey and green makes sense.

 

[RunAgroundHard]

Bare gelcoat below the waterline can be clear, above the water line whatever tint they used. In my case, clear below the water line and white above it. I understand that it was a cost saving thing decades ago as pigment was an extra cost to the basic gel coat formula. The clear colour is in fact an opaque grey colour because of the resins and gas fibre stands under the gel coat. On my own boat (1973/4 build) it is obvious when the old antifoul is removed.

 

[Tranona]

Bare gelcoat below the waterline can be clear, above the water line whatever tint they used. In my case, clear below the water line and white above it. I understand that it was a cost saving thing decades ago as pigment was an extra cost to the basic gel coat formula. The clear colour is in fact an opaque grey colour because of the resins and gas fibre stands under the gel coat. On my own boat (1973/4 build) it is obvious when the old antifoul is removed.

Rather the opposite. The purpose of the clear below the waterline was to provide a visual clue of thorough wetting out and because unpigmented resin was considered less permeable. Far from being cheaper it was more epensive and more work to apply so was only common on more expensive boats - advertised as a positive selling feature at the time when osmosis was starting to become am issue..

 

[lusitano]

Arr ok that’s interesting.

So if the grey is bloody hard and can only be removed with a sharp scraper, then the chances are that it is in fact gel shield and not very very well adhered antifoul primer from over 8 years ago prior to my ownership of the boat?

The presence of Gelshield would indicate either a previous osmosis treatment, or, an anti osmosis precaution. If it,s the former, then the original gelcoat has probably been removed altogether

 

[RunAgroundHard]

Rather the opposite. …

Thanks for the correction. I don’t have any data to debate the point beyond a recollection that I read the reason on here an age ago on a similar discussion.

 

[Concerto]

Here are a few photos of GelShield being applied to Concerto back in early 2014 after the hull had been fully stripped of antifouling and the gel coat sanded.





These colours are used to show an even oat before the next coat is the alternate colour. I then applied 2 coats of dark blue hard antifouling before 2 coats of Dover White soft antifouling. If I ever see dark blue, then all of the self polishing antifouling has been washed away - but never seen yet after many further coats of self polishing, but useful if I wish to wet sand back to reduce the layers. The photo below shows what Concerto looked like when ready for launching with Dover White (it is grey before entering the water) and the style line was painted in Oxford Blue and the boot top was black.

 

[Sandy]

@Tim Good If you are in Mylor and want Coppercoated then you are in the right place as they have a shed that they do it in.

I had the boat done there before COVID and was impressed with their set up.

 

[Tim Good]

Here are a few photos of GelShield being applied to Concerto back in early 2014 after the hull had been fully stripped of antifouling and the gel coat sanded.

View attachment 171767

View attachment 171768

These colours are used to show an even oat before the next coat is the alternate colour. I then applied 2 coats of dark blue hard antifouling before 2 coats of Dover White soft antifouling. If I ever see dark blue, then all of the self polishing antifouling has been washed away - but never seen yet after many further coats of self polishing, but useful if I wish to wet sand back to reduce the layers. The photo below shows what Concerto looked like when ready for launching with Dover White (it is grey before entering the water) and the style line was painted in Oxford Blue and the boot top was black.

View attachment 171770

thanks very useful

 

[Tim Good]

@Tim Good If you are in Mylor and want Coppercoated then you are in the right place as they have a shed that they do it in.

I had the boat done there before COVID and was impressed with their set up.

Yes they’re very good but the quote was huge as the rig needs to come down, sand blasted and then completed in a humidity controlled shed. Close to £10k quote. Since I am going to be out of the water in June still and there is no need for sand blasting then I can do this job myself for less than £2k. This way I can also ensure it is done to the highest standard of application. But I do agree Mylor is one of the best places to have it done if you have lots of £££.