Soda blasting - be careful!

[Supine Being]

Hi all. I don't know if this is a well known problem but my neighbour in the boatyard had his hull soda blasted in the week. I came along today to find my cockpit like this:

It looks like some sort of chemical reaction. The contractor concerned was very apologetic and has promised to sort it out, but given that he has never seen it before I wonder if he knows how to shift it. If anyone has seen this and has fixed it, I'd love to know how.

 

[Len Ingalls]

Vinegar?

 

[longjohnsilver]

I'd ask Elessar over on the mobo forum, he's the most likely to know.

 

[pvb]

In the marina I'm in, boats have to have a polythene skirt attached before any hull blasting takes place. Seems like a good idea.

 

[JumbleDuck]

Hi all. I don't know if this is a well known problem but my neighbour in the boatyard had his hull soda blasted in the week. I came along today to find my cockpit like this:

[...]

It looks like some sort of chemical reaction.

Baking soda forms a mild alkaline solution which probably makes quite a good paint stripper given a lot more time to work - a few days, say - than stronger alkalis like sodium hydroxide. A saucepan full of hot bicarb solution is a good paint stripper for small non-porous items, as the temperature makes up for the mildness. Thank you Professor Arrhenius. Looks like you're going to have to repaint, but on the bright side you know to use a yellowish primer, a greyish undercoat and a white topcoat.

 

[J Neeves]

It looks like some sort of chemical reaction. The contractor concerned was very apologetic and has promised to sort it out, but given that he has never seen it before I wonder if he knows how to shift it. If anyone has seen this and has fixed it, I'd love to know how.

I am firmly convinced that the first thing anyone learns when joining the marine industry is a stock, standard answer:

"That's amazing - in all my years I have never seen anything like that before'


Admit nothing, even if it happened yesterday and regularly before that.

Jonathan

 

[jerrytug]

I am firmly convinced that the first thing anyone learns when joining the marine industry is a stock, standard answer:

"That's amazing - in all my years I have never seen anything like that before'


Admit nothing, even if it happened yesterday and regularly before that.

Jonathan

Ha ha, and not just the marine industry..

 

[Supine Being]

Baking soda forms a mild alkaline solution which probably makes quite a good paint stripper given a lot more time to work - a few days, say - than stronger alkalis like sodium hydroxide. A saucepan full of hot bicarb solution is a good paint stripper for small non-porous items, as the temperature makes up for the mildness. Thank you Professor Arrhenius. Looks like you're going to have to repaint, but on the bright side you know to use a yellowish primer, a greyish undercoat and a white topcoat.

Actually, it doesn't seem to have removed paint, just stained the surface very badly. I was able to budge some of it from the smooth surface using one of those magic sponges, but that won't do any good on the gripped surfaces. I'm thinking (hoping) that we'll be able to shift it with the right solution (maybe vinegar as a previousoster suggested). But it can't be the first time this as ever happened with soda so I'm throwing myself at the mercy of the hive mind!

 

[Supine Being]

In the marina I'm in, boats have to have a polythene skirt attached before any hull blasting takes place. Seems like a good idea.

He promised the yard that he would, and this seems to be the case or else the damage would be much worse. But he clearly had a leak somewhere.

 

[Supine Being]

Here we go... I found this: http://www.cruisersforum.com/forums/f55/soda-blast-residue-causes-gel-coat-discoloration-94048.html

Clearly, soda blasting isn't the easy, harm-free solution that some people think.

 

[JumbleDuck]

Actually, it doesn't seem to have removed paint, just stained the surface very badly. I was able to budge some of it from the smooth surface using one of those magic sponges, but that won't do any good on the gripped surfaces. I'm thinking (hoping) that we'll be able to shift it with the right solution (maybe vinegar as a previousoster suggested). But it can't be the first time this as ever happened with soda so I'm throwing myself at the mercy of the hive mind!

I would strongly suggest that you try nothing more than soap and water yourself, and maybe not even that. It's the contractor's problem to put right, and you don't want to give him the slightest opportunity to say "I could have sorted it easily but you made it worse with vinegar/tippex/virgin's tears/coconut milk/whatever". It would also be worth letting your insurers know, and informing the yard formally, since they will presumably have checked the contractor's public indemnity insurance.

 

[J Neeves]

I would strongly suggest that you try nothing more than soap and water yourself, and maybe not even that. It's the contractor's problem to put right, and you don't want to give him the slightest opportunity to say "I could have sorted it easily but you made it worse with vinegar/tippex/virgin's tears/coconut milk/whatever". It would also be worth letting your insurers know, and informing the yard formally, since they will presumably have checked the contractor's public indemnity insurance.

+1 and I wouldn't even touch it at all. I know you have photos, I might take more and maybe some close ups. I'd check my previous photos for the same areas prior to the damage (hopefully they are dated.

Jonathan

 

[Supine Being]

Thanks JumbleDuck and JM. I'm not about to touch it myself for the reasons that you state. But as the guy doesn't appear to know what to do, I thought I'd throw out some feelers. The yard are certainly aware but I think you're right that my insurers need to know.

 

[Elessar]

I'd ask Elessar over on the mobo forum, he's the most likely to know.

Sadly I don't i never used soda so I'm guessing. What I do know is soda blows around for a long way and disolves, leaving whatever was blasted off as a residue on boats and cars for quite a distance. So consider that the reaction may be with whatever the soda blasted, rather than with the soda itself. That might give a clue on how to treat. But as I say, it is a guess.

 

[oldbilbo]

I'd take some further photos - without the bristle brush being evident. Something else, such as a ruler or a winch handle, could more helpfully give a sense of scale.

 

[Supine Being]

Sadly I don't i never used soda so I'm guessing. What I do know is soda blows around for a long way and disolves, leaving whatever was blasted off as a residue on boats and cars for quite a distance. So consider that the reaction may be with whatever the soda blasted, rather than with the soda itself. That might give a clue on how to treat. But as I say, it is a guess.

I was wondering that as well. The dust residue doesn't look like soda alone, but soda and antifoul. Here's a closeup where I haven't touched it with water. You can see the powder still in situ.

I'd take some further photos - without the bristle brush being evident. Something else, such as a ruler or a winch handle, could more helpfully give a sense of scale.

I took a few shots before I touched anything with the dust still there. I've applied nothing but water and stopped right there when it didn't shift... just washed away the residue.