Struggling with 'Strippit'

[oldbilbo]

I'm having a drawn-out 'first date' with the West Country's 'Reactive Resins' antifoul remover 'Strippit'. Despite using lots, leaving it on a l-o-o-o-ng time, then using an industrial jet wash ( 2500psi ) machine, the results so far are 'patchy'.

The very soft outer layer of antifoul - light blue - came off, together with much of the slightly darker blue layer underneath. There's a residual 'black' layer that seems untouched anywhere by the oxalic acid preparation, and I'm not certain it IS simply old antifoul paint.

There are multiple areas where small 'holes' have appeared in this black coating, as seen in pics below, and I'm wondering about 'boatpox' and a partly-effective overcoat, then further overcoats of antifoul paint....

I want to know what I have here, before deciding on pressing forwards towards a Coppercoat application. This would require an expensive soda blasting exercise..... then probably an epoxy barrier coat, then Coppercoat....

Can anyone with deeper experience of this situation help me determine what I'm now seeing?

...or should I simply slap on some 'El Cheapo' bottom paint and get on with it?

 

[Elessar]

I'm having a drawn-out 'first date' with the West Country's 'Reactive Resins' antifoul remover 'Strippit'. Despite using lots, leaving it on a l-o-o-o-ng time, then using an industrial jet wash ( 2500psi ) machine, the results so far are 'patchy'.

The very soft outer layer of antifoul - light blue - came off, together with much of the slightly darker blue layer underneath. There's a residual 'black' layer that seems untouched anywhere by the oxalic acid preparation, and I'm not certain it IS simply old antifoul paint.

There are multiple areas where small 'holes' have appeared in this black coating, as seen in pics below, and I'm wondering about 'boatpox' and a partly-effective overcoat, then further overcoats of antifoul paint....

I want to know what I have here, before deciding on pressing forwards towards a Coppercoat application. This would require an expensive soda blasting exercise..... then probably an epoxy barrier coat, then Coppercoat....

Can anyone with deeper experience of this situation help me determine what I'm now seeing?

...or should I simply slap on some 'El Cheapo' bottom paint and get on with it?

You must coppercoat over a sound, two pack base.

First see if it is single pack paint. Nick some of your wifes nail varnish remover pads. If the paint doesnt stain the pad, it can stay on. Note the first pass will have coloured dust on ignore that. To test if it is sound, stanley knife a patch of criss crosses, to give little squares about 5 mm square. Put some tape on the patch and pull it off. If most of the squares stay put its sound.

If it isnt you need to scrape it you cant blast epoxy off.

The holes either need to be sanded to a feathered edge or filled. The end result may be patchy colours with bits of epoxy and bits of no epoxy. This is ok if it is smooth. Shut your eyes and see if you can detect the epoxy/gelcoat edge with your finger. If you can, sand or fill some more.

Once sound and smooth, on with the Coppercoat.

Hassle, but the last hassle youll have.

 

[VicS]

Strippit is caustic soda based, not oxalic acid.

It sounds as though you have got down to an old two pack coating which is resistant to caustic soda.

 

[oldbilbo]

Thanks to both. I'll dig a bit deeper into this over the next day or two, then reach for my trowel....

 

[Hoolie]

The chips may be caused by your high-pressure washer. I stopped using a pressure washer on the decks when I realised it was chipping the gelcoat.

Are the chips underneath the anti-foul in areas you haven't pressure washed or stripped?

 

[Grajan]

looks to me like??? Soft blue A/F, VC tar black and pock marks are osmotic/solvent blister reaction below the VC tar, but I could be wrong.
if it is the later throw a coat of AF on and go sailing for this season and work out a plan as to which way forward you want to go, as in, slurry blast /peel, dry out process, epoxy treatment then your coppercoat
As you have been advised that the stripper is a caustic remover no point in advising you that oxalic acid requires air AND substrate temperature to work effectively.
Graham G

 

[oldbilbo]

The chips may be caused by your high-pressure washer. I stopped using a pressure washer on the decks when I realised it was chipping the gelcoat.

Are the chips underneath the anti-foul in areas you haven't pressure washed or stripped?

I have some Silverline sanding mesh en route. I'll try that where the light blue a/f hasn't yet been shifted, then look for evidence of more chips/holes. Right now, I'm starting to feel that 'Sunsail' isn't such a bad idea after all.....

One good thing - the wavy-edge boot topping was just wiped away.

 

[William_H]

Caustic Soda as a painth stripper

I have used Caustic Soda as a paint stripper and found it quite disappointing on antifoul (Jotun ) paint. it barely seems to soften the outer layers. Yet where it drips onto my trailer paint (silver frost/ aluminium anti rust paint) it just strips the paint before your eyes. And of course caustic is horrible stuff it just dissolves horse hair brushes and burns the skin.
Anyway boat coming home for the winter next week (antipodes) I will mostly be sanding down with wet and dry sand paper and slapping more Jotun on in September. No I don't especially love jotun it just seems to be the one I use. olewill