Removing paint from steel - whole thing?

[tomski]

Progressing with my BR 42 project, I have found a total of 8 rust spots on average about 5 inches in diameter in each case so nothing terrible...and the steel an inch or so away from the spots seems to be very solid...there is also a fair bit of surface rust on the deck (stantion bases, bollards etc) and one of the hatches needs to be replaced...

So I think the two options to me are... first to only spot repair what is rusted, then carry out an ultrasound to ensure that the rest is ok...the second is to remove all paint back to bare metal and start again, fix what's rusted, prime her etc...

End state is that I will epoxy her to a smooth finish but want to make sure she will be done properly so I'm leaning towards removing all of the pain to bare metal and primer her properly

In doing so my question is what is the best and cheapest method of doing that...the options that I think I have are:

1. Grit blast - expensive and probably not possible due to the amount of boats around mine
2. Sanding - with a proper sander and 40grit paper, sand the whole thing down
3. Angle grind the paint off - not sure if that's an option? someone suggested it but I'm worried about the dints it may leave behind
4. Heard about high pressure water removal - works like grit blasting but not sure if that is an option either..

I have some paid labour help which isnt expensive so if sanding is the right method then I can get the chap to do it for me over a course of a couple? of weeks...but wanted to hear your opinions

 

[CreakyDecks]

I confess I don't know anything about this but it would seem to me that the only way stripping right back to bare metal would be of any benefit would be if you could do it quickly, under cover and then prime the metal immediately. Otherwise I'd expect it to end up more rusty than it started off! Even if you had it blasted externally and re-primed, it might still rust through from the inside!

 

[tomski]

Yea I thought of that issue also but not sure what the answer is to that...I guess do it in parts..ie keel one side then hull one side etc...

 

[TQA]

Grit/bead blasting is the way to go. The blasting and first coat to be done on a hot dry day.

Grit or bead blast to Swedish standard SA-2.5 anything else just does not cut it.

2 coats zinc rich epoxy, several coats epoxy primer, 2 coats linear 2 part polyurethane top coat.

N.B. The first coat of primer to applied withing 30 mins of completing blasting.

If you intend to sail to the Caribbean spot repair the existing finish and get the above done in Venuzuela. Hot dry and CHEAP!

I lived on and maintained an old steel boat for 7 years.

 

[electrosys]

... what is the best and cheapest method of doing that [removing all of the pain to bare metal and primer her properly]

Regret to say that "best and cheapest" are mutually exclusive words in the world of steel boats. Grit-blasting back to white metal followed by phosphate primers and several layers of 2-part epoxy paint is the only worthwhile procedure worth talking about.

If it were my boat, I'd fit one of those truly barbaric wire brushes in an angle grinder and take the bad areas back to bare steel - as clean as you can get it. Then treat with at least 2 coats of a quality high-build zinc phosphate primer such as from Leighs Paints. Then a couple of coats of whatever is around. That should hold the rust away until you figure out the next step.

Sourcing a cheap labour area (as per TQA's post) for a complete blast and paint sounds like a very good idea. You might also want to investigate India and Thailand.

 

[tomski]

Hi there, I thought that cheap and good is not going to pair up The problem that I have is that I dont think I can grit blast where the boat is due to the number of boats in the yard..would have to discuss with the boat yard I guess but they were not too keen when discussed last...

So would the alternative (wire brush or heavy paper ie 40grit) be suitable? Unfortunately I wont be over Carribean way until 2013 I'd say so need something done here...

 

[Grajan]

If you are not able to blast, patch repair using an angle grinder to take steel back to a bright finish wire brushes only polish the steel heavy grit papers are difficult to use - to keep the price down a single pack aluminium based anticorrosive primer will be very effective - apply two coats then fill and fair followed by a further three/four coats of primer prior to finish coats - you need to achieve 250 microns dry film thickness above water and 350 microns below + antifouling to give the coatings a chance of working.
Be very aware of the dangers if considering using Zinc Rich coatings below the waterline
If you are aware of the products currently on the boat stick with them as it will save problems from intercoat tensions

 

[TQA]

Hi there, I thought that cheap and good is not going to pair up The problem that I have is that I dont think I can grit blast where the boat is due to the number of boats in the yard..would have to discuss with the boat yard I guess but they were not too keen when discussed last...

So would the alternative (wire brush or heavy paper ie 40grit) be suitable? Unfortunately I wont be over Carribean way until 2013 I'd say so need something done here...

Then like I said do a quick patch job.

A needle gun is the weapon of choice for rust removal

http://www.nationaltoolhireshops.co.uk/Low-Vibration-Needle-Gun-60062-for-Hire/

but a disk grinder will do as second best followed by by Naval Jelly or similar rust treatment and some paint.

Then in 2013 go to Venuzeala and get it blasted and painted. Varadero Caribe Cumana has a good rep. run by English speaking brothers, they are good peole.

 

[tomski]

Right so thats option one...I just discovered ultra high pressure blasting...any comments on that solution?

 

[Novachris]

Right so thats option one...I just discovered ultra high pressure blasting...any comments on that solution?

Never tried it, but i work on a oldish steel ship and keeping rust at bay is an ongoing chore.

I would second the suggestion of a needle gun or windy hammer as we call it,it is the tool of choice for us as it is easy to use, gets in there, and is, i suppose relativly cheap to hire.

Once down to bare metal give it a good wire brushing and slap on two coats of red primer.and then, and this is the important part, give 4 coats of quick drying undercoat. dont have to be quick drying but i suppose the faster the paint goes off the less moisture gets in.

then slap on one coat of topcoat of choice, we use single pack as it is cheaper and not so fussy.

Sorry just reread your post, the method above is suitable for the smallish rust areas you describe. I think the way you want to go will be hellish expensive, and are you sure totally necessary?
Good luck.

 

[Conachair]

Assuming shot blasting is not an option..
Never used a needle gun but they do get good press from a hard to please crowd so quite likely to be good. Small bits I grind to shiney gently to try and not loose too much material. But never manage to get all the rust out. I use ospho as a treatment to convert the rust to iron phosphate. People have different views on phosphoric acid but in my experience in hotter climes you will never get the rust out of the pits even with grinding. It will look clean as a whistle but stick some ospho on in hot sun and watch it bubbling away in the invisable pits. So you can paint over iron oxide or iron phosphate.

One thing which is not allowed onboard anymore is single part paint.
2 part all the way now. Once you put some single part on you're stuffed, no going back without taking it all off. Amerlok sealer is the holding coat of choice, takes ages to go off and soaks into every little nook and cranny you can't reach. I stick with ameron for high build coats after that, then some car 2 part polyurathane as a top coat, lot cheaper the marine stuff and seems to hold up just as well.

If it's on the outside then it shouldn't be too much of an issue, though not really the weather to be working with 2 part epoxy. It's the inside you really want to be keeping an eye on

 

[Grajan]

Ultra high pressure water blasting is very good, very expensive (or was) and specialized primers are required - plus you will have to hire machine and operative as in the wrong hands these machines will do unbelievable damage!
the problem with needle guns is that they remove the blast profile from the initial blast primed steel, and the coatings need that to "hang" on to! great for removing scaling rust but for small yacht "rust rash" it will only deafen those all around and leave a very poor surface to coat onto,
dont mix single pack and twin pack products unless the twin pack has already been applied as you will need to blast prior to applying two pack or you might as well just throw your money away,You should be able to pick up marine quality coatings from International Hempel, Jotun, Leighs, and Teamac at competitive prices. Lookout for coatings that have "come over the wall" and are in opened drums as they can contain more gunwash than paint!!!

 

[tomski]

I know the needle gun well from me navy days lol...great tool for rust and removing old stuff but takes bloody ages for this kind of work as I really want the whole hull and deck done...though needle gun will be perfect for the interior..
I talked to one of the ultra high pressure providers and cost wise well looking at over £1k to do the hull and deck...some additional costs for transport so we'll see whats the final figure..
work wise its about 2-3 days...this system also removes all of the chemicals and salts left over in the hull at micro level...

I'm leaning towards this option, its not cheap but then I know its done 100% and better than grit (though more expensive) (apparently)...well see what the different quotes come back at I guess...if that fails then I will follow your advise on sorting out the rust spots but the only concern is that I wont get to see the whole hull...food for thought

I think I mentioned but I will want to flair the hull out with epoxy filler after the primers...providing the coating is done right the guarantee with this is 30 years...so then would only have to worry about interior I guess

 

[Grajan]

I would look atthe small print in that g/tee very carefully, normally for any g/tee there has to be a quality control supervisor on site throughout the blasting filling and coating process Overcoating times temperature and humidity have to be adhered to or with epoxies if overcoating times are exceeded a light grit sweep could be called for prior to completing coating schedule.

25 years in the paint industry and I never paid out on a "g/tee" claim, maybe gave away some material but NEVER paid for a reblast

 

[Pasarell]

I agree with Grajan (hardly surprising) but disagree strongly with some of the other advice given above. If someone has offered you a 30 year guarantee I would start running - away. Not going to happen. If you had a large ship you might get 10 years in the form of an insurance policy - and in year 10 the payout for complete failure will be only about 10% of the original value of the job.
Hydroblasting is very good and keeps the mess down well but be sure what you are getting. There are many operators who claim startling results but actually provide little more than high pressure washing. You want at least 35000psi to be used. At that pressure the price is quite high, especially for small jobs where mobilisation costs will be high. No point in doing it unless you are going to apply a good quality paint system in good conditions. Be aware, also, that this form of preparation will not improve the steel profile so unless it was blasted when new you may be wasting money.

If you are doing a proper job avoid rust converters. There is a very good reason why no major paint company recommends them. Especially below water! If you end up doing a quick repair job prior to a full blast later there may be a case for using rust converters if the steel is badly pitted.

Avoid using red lead or red oxide primers. Always. They are not what the name implies and have no anticorrosive pigments worth speaking of.

There are good single pack zinc anticorrosives available now called moisture cured urethanes. Much more tolerant to temperature / humidity / overcoating times than epoxies but with the same performance as 2 pack epoxies. This has to be the way to go if you do the job in the UK during the winter. Good for spot repairs as well as after a full blast.

Grajans comments about dry film thickness (dft) are critical. If you are doing a full job it will be worth buying a gauge or hiring one. Basic gauges are often available on ebay quite cheaply. You will be amazed how little paint you apply in each coat by brush or roller. Spraying is more predictable but probably not an option if you have other boats around you. If you skimp on dft you will be wasting your time and money. Check your dft after each coat, but when you think the job is complete do a thorough survey. At least 10 measurements / sq m. There will be low points that need spot applications to touch in.

On edges, corners and weld seems you will get a much thinner coating than on flat panels, and these are the places most likely to break down first. Apply a stripe coat to these areas after each full coat if you are brushing / rolling. If you are spraying apply at least one stripe after the first full coat. A stripe coat is a brushed coat with emphasis on working the paint into all cracks and crevices.

If I was you, and doing a proper job in good conditions in 2 years rather than a compromised job now I would just touch in the problem areas at the moment. Good luck with whichever you choose.

 

[tomski]

Right I think I should clarify the 30 year guarantee...so this is the guarantee that the epoxy people were talking about for when I wanted to fair the hull but thank you on your points re such guarantees, will keep my eyes open

The blasting is a different animal...the company I spoken to blast with ultra high pressure starting at around 45000 psi up to 60k and they blast to the original blast profile...if one is not available then they can blast profile (using another method which involves raw material and water which actually is a bit cheaper and ultra high pressure)....

Then either I paint or they paint, painting apparently can be carried out right after blasting, still waiting on details on that...

my idea was to blast it then give it the right number of coats to preserve it and in spring fair out with epoxy filler...biggest problem I have is that I dont know what is there already (and its a rather poor job but seems to hold well) hence was keen on blasting

The other option of spot fixing is an option but I dont know for sure that in 2 years time I will be going to the Caribbean, may end up staying in the Med so dont want to put such thing off too long....

 

[Annie-li]

I think the last option will be the best way, I have saw such a operation.

You also need ultrasonic antifouling system?

If so, contact me, I am a manufacturer.

 

[Jassira]

I've owned a steel BR53 for the last 10 years, and how best to paint her is never far from my thoughts, you'll get use to it
It seems the best you can do is grit blast to SA... something or other, then paint with modern, epoxies. Problem is that the requirements for temperature, humidity, time between blasting and painting etc can be very difficult to achieve when your trying to work to a budget, outdoors, in a boat yard in the UK, and surrounded by other shinny plastic things.

I think that it's better to the best I can as soon as I can, rather than wait till everything comes together to give me the perfect conditions. My weapons of choice:

a) 3hp compressor, I also have a 2hp compressor that I often couple together but a 3hp will do the job
b) Needle gun
c) DIY 10gallon blast pot.
d) Spray gun with a 2lt pressure pot

I needle gun any thick layers of paint and or rust spots, then I blast using J-Blaster superfine, and paint with either 2 pack coal tar epoxy or Jotun Vinyguard/Pioneer top coat. Coal tar requires no primer nor top coat, just coat on coat, In fact you can't over paint it as the tar will just bleed through.
I use coal tar below the water line, inside and out, vinyguard everywhere else.

It isn't technically the best approach, but in the real world I think it's the best I can do, and it seems to work pretty well.

PS.. grit blasting the interior is probably the dirtiest job in world...

 

[Tradewinds]

my idea was to blast it then give it the right number of coats to preserve it and in spring fair out with epoxy filler...

My 2p's worth.

Why do you want to fair out with filler? Whatever you do it's always going to be obvious that it's a home-built, hard chine steel boat like all the other home-built hard chine steel boats out there on the water. And it's one more finishing system to fail/go wrong.

If it was me I'd patch repair where necessary get the rest of the boat sorted for sailing/liveaboard. It will never look anything else but what it is. 100% agree with taking it somewhere warm & doing the blasting there. You never know, by the time you get there you might be more than happy to live with what you've got & just carry on patching as you travel along.

BTW don't get me wrong - IMO there's nothing wrong at all with the above sort of boat, as long as they're out on the water doing what they should be doing - cruising to far off places (ref: www.yachtmollymawk.com) like 100's of others.

Good luck with the project.

 

[tomski]

Hi Jassira, thank you that makes a lot of sense and is something that would be manageable by me.

Tradewinds, that's what I'm battling with...For the money to be spent on blasting, then paiting then fairing I defo would be able to restore him properly inside (she's not that bad inside actually) and fix all the issues outside...

Definitely not worried about cosmetic look as I love the fact that its unique, but the blasting was more of a strip back to ensure there is no further rust hiding anywhere...plus the prob of not knowing what is painted on her...she doesnt look bad (the paint job) a lot worse on deck than hull and below waterline...

But I need to give serious thought on this...as you say it may be the case that I will get used to patch and paint...hmmm