Recycled Bottle Glass Blasting to Remove Antifoul

[arh]

Hi all,

Thinking of having the hull blasted using recycled glass to remove the old anti-foul on the new to me boat prior to a fairly major refit over the winter and then coppercoat applied.

Hear conflicting stories of whether the blasting damages the gelcoat or not.

Does anyone have any experience of having antifoul removed using this system ?

I have searched the site but most of the posts relate to soda blasting rather than crushed recycled glass.

Thanks

Tony

 

[Plevier]

I have had two boats dry blasted.
The first, done by a local bloke using Olivine - a relatively soft natural mineral - as the blast material, was brilliant.
The second, done with crushed glass by a supposedly specialist company that used to appear quite frequently on this forum, was disastrous, through the gelcoat in numerous places. (Incidentally their website claimed that they used Olivine, but it visibly wasn't, the guy doing the job told me they had changed to crushed glass because it was much cheaper.)

My conclusion is that the crushed glass is too harsh. Olivine breaks up into dust when it hits, I don't think the glass does.

However you are dependent on operator expertise too.

 

[savageseadog]

I have had two boats dry blasted.
The first, done by a local bloke using Olivine - a relatively soft natural mineral - as the blast material, was brilliant.
The second, done with crushed glass by a supposedly specialist company that used to appear quite frequently on this forum, was disastrous, through the gelcoat in numerous places. (Incidentally their website claimed that they used Olivine, but it visibly wasn't, the guy doing the job told me they had changed to crushed glass because it was much cheaper.)

My conclusion is that the crushed glass is too harsh. Olivine breaks up into dust when it hits, I don't think the glass does.

However you are dependent on operator expertise too.

The olivine is just smaller and better graded, it doesn't break up. Olivine is one of the best but more expensive blast medias.

 

[Daydream believer]

Mine was done with sand. The bloke stood well back and did it with care. No problem at all
Coppercoat manufacturer say that the gel coat is irrelevant . Give them a ring and they will confirm that it is just "cosmetic"
However, my gel coat was ok. If you are worried stick on a couple of coats of gel protector first

 

[Plevier]

Mine was done with sand. The bloke stood well back and did it with care. No problem at all
Coppercoat manufacturer say that the gel coat is irrelevant . Give them a ring and they will confirm that it is just "cosmetic"
However, my gel coat was ok. If you are worried stick on a couple of coats of gel protector first

I hope not. Use of real sand (containing silica) has been banned since 1950 because of silicosis risk and people have been heavily fined for using it.
(Of course the word is used loosely to mean blasting abrasives that are not really sand.)

 

[Daydream believer]

I hope not. Use of real sand (containing silica) has been banned since 1950 because of silicosis risk and people have been heavily fined for using it.
(Of course the word is used loosely to mean blasting abrasives that are not really sand.)

Apologies
I stand corrected.
However, when i had my wooden stella blasted (1999) ihad to remove bucket fulls of what looked like fine sand from inside the hull. Perhaps it was glass but i would be surprised
When they did my grp hull the chap had just finished cleaning some steel at the marina and i am sure he did not change the grit
The point being in my post that i did not specify any particular method, just the cheapest going. Perhaps it was the skill of the operator but all went well

 

[Seajet]

Be very careful about getting your boat blasted !

At my club 5-6 owners got together and had a chap blast them, he promised just to remove the layers of old antifoul...

Several if not all of them got their entire gelcoats below the waterline balsted off, requiring serious work to repair, insurance jobs and lost seasons.

If I knew the name of the company I'd say it here, but this was a few years ago and I think the chap would be lucky to be alive now, unlikely to still be trading at this !

I think blasting OK and am considering it next winter, but be be very sure to research the company.

 

[Elessar]

I have had two boats dry blasted.
The first, done by a local bloke using Olivine - a relatively soft natural mineral - as the blast material, was brilliant.
The second, done with crushed glass by a supposedly specialist company that used to appear quite frequently on this forum, was disastrous, through the gelcoat in numerous places. (Incidentally their website claimed that they used Olivine, but it visibly wasn't, the guy doing the job told me they had changed to crushed glass because it was much cheaper.)

My conclusion is that the crushed glass is too harsh. Olivine breaks up into dust when it hits, I don't think the glass does.

However you are dependent on operator expertise too.

That was probably my old company then. I hope after I left it.

Glass and olivine work in exactly the same way. They split on impact. To the operator you can't tell them apart and the finish is the same.

Dry blasting is the harshest and cheapest. Wet blasting is gentler.

But....

A super skilled operator on dry will get a better finish than a poor operator using wet.

If I was having my boat blasted now, I would insist on a wet blast with glass , and insist on seeing some work done by that actual operator, not just that company or machine.

It is quicker and easier to learn wet blasting than dry, there are few absolute experts with dry I reckon.

The thing is it is a horrible job to do and boat owners want the cheapest price. It is therefore hard to retain staff.

The guy who bought my machine in the end is not competing on price and will take 2 days to do the job. Some dry blasters do 4 or 5 a day! What he is doing is absolutely immaculate.

I'll pm his details if you believe a word I say but given your experience you may not want to!

 

[arh]

Thanks for all your comments, these coupled with the ones on the other thread for 'top and bottom cleaning' seem to support wet slurry blasting as the way to go with removing antifoul before coppercoat, with the proviso that the company is experienced and has good operators.

Anyone heard of, or had experience with Gentle Touch Blasting from near Conwy North Wales ?

I will contact them to try and get some references and if i proceed then will report some feedback (good or bad) on hear.

Thanks

Tony

 

[Daydream believer]

The guy who bought my machine in the end is not competing on price and will take 2 days to do the job. Some dry blasters do 4 or 5 a day

I was present when the chap did my 31 ft boat. Took 3 hours inc setting up etc
I stood there all the time he was working ( at his request) and agreed the extent of material removed
He left some isolated patches of antifoul to avoid being too harsh ( at my request) and it took about 6 hours for me to clean off not inc 50mm at wayerline

When i had my wooden Stella done inside and out it took the chap a full 2 days working quite hard.
He panicked when he blew a hole through the hull and came rushing into my office quite agitated. However, when i pointed out that it was rot and he had saved me some time removing it he was very releived

 

[Plevier]

That was probably my old company then. I hope after I left it.

Glass and olivine work in exactly the same way. They split on impact. To the operator you can't tell them apart and the finish is the same.

Dry blasting is the harshest and cheapest. Wet blasting is gentler.

But....

A super skilled operator on dry will get a better finish than a poor operator using wet.

If I was having my boat blasted now, I would insist on a wet blast with glass , and insist on seeing some work done by that actual operator, not just that company or machine.

It is quicker and easier to learn wet blasting than dry, there are few absolute experts with dry I reckon.

The thing is it is a horrible job to do and boat owners want the cheapest price. It is therefore hard to retain staff.

The guy who bought my machine in the end is not competing on price and will take 2 days to do the job. Some dry blasters do 4 or 5 a day! What he is doing is absolutely immaculate.

I'll pm his details if you believe a word I say but given your experience you may not want to!

It was done (dry because the wet part of your machine was broken) by the person you said was your best operator.
It took him about 2 hours as I recall, plus the time to sheet up rather inadequately.
I had a lot of complaints from adjacent boats about the mess.
I hope he isn't the guy who has bought your machine.

 

[Elessar]

It was done (dry because the wet part of your machine was broken) by the person you said was your best operator.
It took him about 2 hours as I recall, plus the time to sheet up rather inadequately.
I had a lot of complaints from adjacent boats about the mess.
I hope he isn't the guy who has bought your machine.

Can you PM more details? Ie when and where etc.
I don't recall ever blasting a boat dry btw. Only keels.

 

[Plevier]

Can you PM more details? Ie when and where etc.
I don't recall ever blasting a boat dry btw. Only keels.

Shoreham. 2012.
Your machine was there several days while you got a spare part for it or something, until fixed could only do dry.
We had some pretty heated exchanges at the time.
Matter closed, no point dragging it up again. That's why I didn't identify you but you chose to stand up!

 

[Elessar]

Shoreham. 2012.
Your machine was there several days while you got a spare part for it or something, until fixed could only do dry.
We had some pretty heated exchanges at the time.
Matter closed, no point dragging it up again. That's why I didn't identify you but you chose to stand up!

OK I have to admit I don't recall, and am a bit confused as the blue pot was wet only but the yellow one could do wet or dry. We did do 100's of boats and I apologise if I got one wrong. We didn't do as many as the dry blast operators though, we usually did one a day, only exceptionally 2.

My advice re the wet blast and the operator remains my advice and would be what I would do/ask for on my boat.

 

[ianj99]

I was present when the chap did my 31 ft boat. Took 3 hours inc setting up etc
I stood there all the time he was working ( at his request) and agreed the extent of material removed
He left some isolated patches of antifoul to avoid being too harsh ( at my request) and it took about 6 hours for me to clean off not inc 50mm at wayerline

When i had my wooden Stella done inside and out it took the chap a full 2 days working quite hard.
He panicked when he blew a hole through the hull and came rushing into my office quite agitated. However, when i pointed out that it was rot and he had saved me some time removing it he was very releived

Had a similar experience with my steel ketch, wet ground glass bead blasted. He went through under the head and chain locker and I was glad he did otherwise a bump from an unseen log would have led to disaster. It took a day to dismantle the interior to get at the holes so we'd have sunk well before the leak could have been stemmed.

The steel was left with a minute dimpled finish, though only where the epoxy layer had separated, sound epoxy was not removed just left with the dimpled finish.
I assume a less aggressive setting on the equipment would be used on gelcoat.