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Soda blasting!

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delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Initially Posted - 01/17/2010 : 14:09:27

Last weekend I was wandering around Harbor Freight, and saw a small handheld sand blasting unit, which got me to thinking, maybe I could use it as a soda blaster and over time, clean the hull on SL with it. I started looking around for blast media and lo & behold, got routed right back to Harbor Freight, where I found this: [url="http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=65902"]

[/url]

Since I knew it was going to cost me at least $400 to soda blast my hull, I figured this wasn't such a bad way to go, and I'd have a soda blaster to use afterward. I bought a compressor a few weeks back, but immediately loaned it to a friend who's had it since. I figured I could use my little 10 gallon air tank to drive it for a while, but had no idea how short that while was. This is the result of about five minutes blasting, about how long the tank lasts.

At least I've alleviated one worry I had, now I know that those "holes" I thought the barnacles left behind are actually little more like little atolls of barnacle glue, and the glue will come off if the pressure is high enough (a very short time indeed with the little red tank). Once I have the compressor back, I should make some good progress. I figure even if it takes me a month of weekends, it's no big deal.

Now I have to figure out how I'm going to get beneath the pads and keel. The pads I'm not too worried about, the keel's a different story. In any case, I'm very pleased with the initial results.

David
C-250 Mainsheet Editor

Sirius Lepak
1997 C-250 WK TR #271 --Seattle area Port Captain --

Edited by - delliottg on 01/17/2010 14:10:22

Ed Cassidy
Captain

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Response Posted - 01/17/2010 : 15:18:08

How much media did you use in that test area?
Thanks,
Ed

Edited by - on

John Russell
Master Marine Consultant

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Response Posted - 01/17/2010 : 15:28:12

I know the soda is environmentally benign but what happens to all the toxins you blast off the bottom? How are they contained? What kind of respriator do you need?

Edited by - on

Unsinkable2
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Response Posted - 01/17/2010 : 15:50:15

Wow David, that's great. I've been looking for a way to clean my hull from the bio buildup in the lake. The pressure washers at the commercial carwashes, but they're not quite powerful enough. I have been contemplating buying a heavy duty pressure washer, but they're pricey. I think I may try the harbor freight soda blaster route!

I've used some of Harbor Freight's tools for the last 15 years. I'm not a mechanic, but work on my own cars and related projects. Their "Pittsburgh" line of ratchets and sockets is a great bargain and although they're not quite snapon or craftsman, they've never slipped or stripped on me. (I haven't been as impressed with their electric power tools (bandsaw, bench sander), they aren't built to very exacting standards.)

What size soda did you use? I see the have large and medium. Also, looks like the 15 lbs canister is the same price as the 15 lbs one.

Great post, thanks!!

Edited by - on

delliottg
Former Mainsheet C250 Tech Editor

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Response Posted - 01/17/2010 : 16:08:45

Not sure how much media was used, maybe 1/5 of the tank? I need to figure out what the usage rate is. It's kind of a pain to load it, you have to unscrew the bottle top, and it's got a cheesy O-ring seal that doesn't work very well, but that point won't matter so much when I have the compressor back. It also had an airline you had to unscrew each time, but I had an extra quick connect & nipple, so now it's not such a pain. I bought 50 lbs of media, I expect to go through at least three bags of it before it's finished. The bag completely filled up a 5 gallon pail with enough left over to mostly fill the bottle. My friend says he'll have the compressor back to me by Wednesday or Friday, which will work out nicely.

I'm wearing a dual cartridge respirator, and the soda is slightly irritating to your skin if it's wet or sweaty. It was raining a bit when I did this, so I had some of both, so my arms and face were a bit umm...itchy? Hard to explain, reminds me of how I feel when salt water dries on my skin. My eyes were watering a bit afterward, but that only lasted for a while. Still have that tight, dried salt water feeling around them though. I'd imagine a shower would fix that.

As far as toxicity goes, after reading the [url="http://www.jamestowndistributors.com/userportal/pdfs/MSDS/Interlux/vc17m_original.pdf"]MSDS[/url], there doesn't seem to be too much danger associated with VC-17 unless it's still in it's liquid state, which this stuff hasn't been in for years. I plan to vacuum up the entire area with my industrial sized wet/dry vacuum as I go.

I was going to buy the 15 lb version if it was the same price, but it's actually $30 more, and they only had the display model available. I bought the XL media I think, but not positive, they only had three bags of media available. I'll check the receipt & figure it out.

Here are a couple more photos of the barnacle glue rings:

Edited by - delliottg on 01/17/2010 16:25:40

bigelowp
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Response Posted - 01/17/2010 : 18:13:23

I think like many of us, the idea of being able to clean our hulls to close to the original condition is on the list of "to do"projects. Your input is very helpful as it tells us what can be done. I keep thinking that the solution of my bottom problems is to soda blast and remove all of the old paint then start over. Thanks for the input.

Edited by - on

Nautiduck
Master Marine Consultant

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Response Posted - 01/17/2010 : 18:45:33

Nice David! Do I see a new business starting - Elliot Unique Soda Blasting?

How does the blasted bottom look? Pretty much like fresh gelcoat?

Edited by - Nautiduck on 01/17/2010 18:46:00

delliottg
Former Mainsheet C250 Tech Editor

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Response Posted - 01/17/2010 : 18:57:47

I wouldn't say it looks like fresh gel coat, and it's possible to be over zealous. I've seen some of the fiberglass looking sort of like egg shell, instead of shiny gel coat. But I can't know what it looked like before I started, so maybe it looked like that before I started (not likely, but possible). Since I have so little time with the air bottle, I don't get a chance to adjust the flow rate. I think what I want is the least amount of media at the highest pressure it'll run, but that's just a guess. I need to do this before I keep going so I don't make more work for myself.

I actually contemplated buying a commercial soda blaster a few months back to go into business doing this. It's actually quite fun to watch the clean hull emerge as you work.

Edited by - on

Dave Bristle
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Djibouti
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Response Posted - 01/18/2010 : 10:53:15

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by delliottg
 ...I'm wearing a dual cartridge respirator, and the soda is slightly irritating to your skin if it's wet or sweaty. It was raining a bit when I did this, so I had some of both, so my arms and face were a bit umm...itchy? Hard to explain, reminds me of how I feel when salt water dries on my skin. My eyes were watering a bit afterward, but that only lasted for a while. Still have that tight, dried salt water feeling around them though. I'd imagine a shower would fix that.

As far as toxicity goes, after reading the [url="http://www.jamestowndistributors.com/userportal/pdfs/MSDS/Interlux/vc17m_original.pdf"]MSDS[/url], there doesn't seem to be too much danger associated with VC-17 unless it's still in it's liquid state, which this stuff hasn't been in for years. I plan to vacuum up the entire area with my industrial sized wet/dry vacuum as I go.<hr height="1" noshade id="quote"></blockquote id="quote">Oddly, in the MSDS, I didn't see any mention of the copper that you mix into the paint... That's toxic to internal organs over the long term, and should not get on your skin, much less in your eyes. It appears the MSDS only relates to the liquid product and the vapors associated with its use, and has nothing to do with the residue from removing the dried paint. In CT, by law, the hull as to be totally tented before the bottom can be blasted. The guys who do the blasting wear complete HAZMAT suits. I wouldn't want that job.

Edited by - Dave Bristle on 01/18/2010 10:57:25

John Russell
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Response Posted - 01/18/2010 : 10:57:00

A good way to eliminate roots from a main sewer drain is to use a copper preparation. It kills the roots and they don't continue to grow and clog the drain. I'd bet that if you put sufficient copper into your yard and let it soak in, you won't have many plant growing.

Edited by - on

OJ
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Response Posted - 01/18/2010 : 15:29:24

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by delliottg

<hr height="1" noshade id="quote"></blockquote id="quote">
This is your brain on drugs . . .

Edited by - on

islander
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Response Posted - 01/18/2010 : 16:40:55

Or
Uh..Huston...The L.E.M is now starting its descent...

Edited by - islander on 02/07/2010 07:27:47

tmhansen
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Response Posted - 01/20/2010 : 22:25:24

I have had good result removing barnacle rings with oxalyic acid. Might save you some blasting media and save you from making little shallow craters on the hull.

A repaint of our hull is on the to do list. I have priced having the bottom soda blasted but it was not something I could do.

Edited by - on

delliottg
Former Mainsheet C250 Tech Editor

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4479 Posts

Response Posted - 01/20/2010 : 22:50:57

Todd,
Thanks for the tip, I was worrying about exactly what you mentioned, blasting little rings into the hull where the barnacle glue was.

I've discovered that I can buy food grade baking soda from Costco for about 1/2 what they sell it for at Harbor Freight, so I'll be looking into that this weekend as well.

We're going to pull the trailer forward enough to get a tarp under it and then back it over the tarp so we can capture the blast media & paint particles. We're also going to get some Tyvek suits to blast with.

I'm actually looking forward to doing this, but I suspect that'll change when it turns to drudgery after a while. I've estimated it could take me as long as 16 hours of blasting to finish, but that's worst case scenario (I hope).

Edited by - on

Ed Cassidy
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Response Posted - 01/21/2010 : 07:48:31

Can you tell if there something special about the blue tank or can any media blaster be used with soda? Actually, do your instructions say the blue tank can be used with sand media? I have a much larger version of the blue tank, also from Harbour.
Ed

Edited by - on

delliottg
Former Mainsheet C250 Tech Editor

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Response Posted - 01/21/2010 : 09:47:45

Ed,
The instructions specifically say that my 10lb blaster can't be used with other media, but I'm unclear as to why. As far as using yours, I'd suppose it can't hurt to try. Go to Costco & pick up a 12lb bag of baking soda from them for $5 or so. If it doesn't work, you've got lots of stuff to freshen your fridge with. I remember reading somewhere that you need special nozzles for soda blasting, but HF sells 10 packs of the nozzles for mine for $13, so at worst you're out less than $20 to find out if yours will work.

I'm not an authority on any of this by any means, this is my first experience with soda blasting, I've only read about it (a lot) before. My only previous experience with blasting is very limited to industrial work, complete suits with helmets & supplied air, giant nozzle, shooting smelting slag against shipping containers to refurbish them at a shipping facility in FL about 20 years ago. It doesn't exactly scale to this.

Edited by - on

OJ
Master Marine Consultant

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Response Posted - 01/22/2010 : 18:14:19

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by delliottg
 . . . The instructions specifically say that my 10lb blaster can't be used with other media, but I'm unclear as to why . . . <hr height="1" noshade id="quote"></blockquote id="quote">

While I don't profess to be an expert on this equipment, I would guess that the hardware leading from the tank to the nozzle determines what media it will deliver.

After removing bottom paint from my 1981 C25 with a random orbital sander

, I am intrigued by this process. The theory that was explained to me is that baking soda has a very sharp edge - but immediately turns to dust after it hits the target surface.

Would love to know how this unit performs with a full (or adequate) size compressor. Thanks for sharing this info!

Edited by - on

delliottg
Former Mainsheet C250 Tech Editor

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4479 Posts

Response Posted - 02/06/2010 : 23:00:08

I finally got a nice weekend day to work on this today and I've learned some stuff I want to pass on. Here's what the hull looks like right now, and no, the top of the keel isn't done, it's just covered in about 1/4" of baking soda:

Leading edge of the keel:

The paddlewheel for the speed log:

Around the front right pad:

So, here's what I've learned:
Dry media is paramount, if you leave an open package it starts absorbing moisture no matter how well you seal it. I've got my "expensive" media sealed in a 5 gallon pickle bucket.

The 13.5 lb bag at Costco of Arm & Hammer baking soda is almost half the price of the stuff from Harbor Freight, and I don't see any difference in performance, in fact, I think because it's so much finer, it's more difficult to do damage to your gelcoat.

I found the 15 lb blaster at HF for the exact same price, so I took my 10 lb one back & exchanged it. I found that loading the cylinder is problematic at best, so I figured I might as well only load it 2/3 times as many times.

Regarding loading, well it's a pain with these units, so here's what I've come up with. I found a big funnel & cut it down to fit over the outside of the throat. It lets me load about 1/4 of a Costco bag at a time. I use a long zip tie chucked up into a drill to agitate the media down into the bottle. It can take about ten minutes to load each bottle, but I'm generally glad of the break. Roughly four funnel's full loads the bottle nearly to the top.

I found a piece of cardboard inside the feed tube which was probably blocking some of the air.

I added a quick disconnect on the downstream side of the air regulator to make it easier to remove the media regulator head when refilling. I also added a 90 degree fitting to route the hose away from the side of the bottle where I thought it might rub.

Buy some extra O-rings (trust me, you're going to lose them, it's a stupid design, fortunately they're cheap). When it says 16mm x 2mm on the manual, they actually mean 21x16x2 (OD x ID x diameter).

Be careful of the regulator / water separator. The plastic retaining ring is sketchy, keep it tight & it's it's OK. The retaining E-clip on the spring loaded water separator valve popped off, I had to crimp it a bit to make it stay on.

My compressor is really too small for the job, even with an 11 gallon separate tank, it's a losing game as soon as you open the blast valve. You really need a compressor capable of ~10CFM at about 90PSI. Mine's capable of about half that CFM and I have to stop & let it catch up after 5-8 minutes.

Just like the Jim Croce song, you don't blast into the wind, unless you like baking soda EVERYWHERE, it's incredibly fine once it's been blasted, and gets into every nook & cranny.

Don't bother trying to blast at low pressure, or when you're below about 1/4-1/5 tank. It's not worth your time shaking, tilting, upending, etc. the tank trying to get the dregs out the pick up tube. Go ahead & reload, take a break and get back at it with a full tank. In my case, it gives me a break, allows my compressor to catch up and cool down (it was blowing breakers until I took the boat heater off the circuit).

Don't get your face too close to the action (you'd think this would be obvious), but I did it a couple of times w/o even realizing till I got blast-back into my face. This happened around the pad, the blast media goes in, and bounces right back out at you. D'oh!

Try not to let clumps get down into the tank, they won't feed up the tube.

I shake the bottle occasionally to move the media around. I think a cone forms down there once the media gets to a certain level and the pickup tube is probably "dry". I've thought about trying to extended it with a piece of copper tubing to route it to the side of the bottle's bottom instead of the center, so it wouldn't be at the bottom of the inverted cone, although it'd probably just create it's own at the side so I'm not sure this is the solution. An ideal solution would be a method to automatically agitate the media. I'm considering a drill running with an eccentric weight to shake the bottle constantly. I've tried dangling it from a post so it's easy to shake, which worked OK, but ended up scraping paint off of it. The design should have an inverted cone at the bottom of the bottle to direct media into it.

If you've had shoulder surgery or injuries, take it easier than I did today, even after sitting in my hottub with a nice cocktail, my arm's complaining, and probably will be all day tomorrow.

Edited by - on

Nautiduck
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Response Posted - 02/07/2010 : 08:16:42

David, it looks like it is working well. Thanks for sharing your tips and tricks.

What I am learning is that there are advantages to being a seasonal sailor in a lake!

Edited by - on

Steve Milby
Past Commodore

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Response Posted - 02/07/2010 : 08:36:33

David, approximately how many hours would you estimate you'll spend to completely strip the bottom and keel with the soda blaster? (I'm asking because a friend wants to strip his similarly-sized boat this spring, and I'd like to pass along your experiences and tips to him. Also, I offered to help him, and want to do it the easiest way.

)

Edited by - on

jbkayaker
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Response Posted - 02/07/2010 : 09:50:36

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by John Russell
 A good way to eliminate roots from a main sewer drain is to use a copper preparation. It kills the roots and they don't continue to grow and clog the drain. I'd bet that if you put sufficient copper into your yard and let it soak in, you won't have many plant growing.
<hr height="1" noshade id="quote"></blockquote id="quote">

See http://www.flickr.com/photos/library_of_congress/2179057520/ for an example of what copper smelting does. Of course that's not what we are talking about here.

Also don't let Harbor Freight get your mailing address unless you want to receive their flyers forever. I have tried 4 times to get them stopped.

Edited by - on

delliottg
Former Mainsheet C250 Tech Editor

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Response Posted - 02/07/2010 : 14:29:32

Steve,
I'd estimate I've stripped maybe 1/6 of the boat so far. I estimated it would take me several weekends working at a reasonable rate (read: slower than you'd want to see your yard worker moving). I didn't factor in my shoulder complaining about it though. I'd say you could do the whole hull in about eight straight hours of blasting. The work I did yesterday was maybe two solid hours (I know the math doesn't add up very well), but there's all the other things to keep in mind, like having to wait for the compressor to cycle, loading the bottle, moving around the boat, shaking the bottle to move the media to the siphon, plus having to learn from scratch about all kinds of things like air tools in general, compressors, fittings, etc.

Dunno how helpful that was, but it might give you an idea.

Let's see if I can rationalize the copper issue. I pulled out one of my extra cans of VC-17 (I've got three, anybody need some?). Each can contains 165 grams of powdered copper that you mix into the paint, which is about half solvent, which is simply alcohol according to the MSDS. When we bought the boat it had VC-17 on it that was fairly weathered. We bought another quart and re-coated it with the same paint concentrating on where it was weathered to get a reasonably good coat of paint on the wear points (bow, leading edge of keel, waterline, etc.). That was three years ago roughly. The copper is designed to leach into the water creating a killing layer to deter attachment of marine growth. I've done a fair amount of research, and while I'm certain there is still some copper on the hull, I'd wager that the 165 grams that we applied has long since leached down to very nearly nil and what was there previously had largely leached out before we bought it. Empirical evidence suggests this is true, simply by the amount of marine growth I have on my hull. Obviously the killing layer isn't effective any more. This suggests low copper amounts left in the paint. I've chosen to protect myself from what's on the hull, NIOSH cartridges in my respirator, gloves, goggles, etc., but honestly I'm more worried about the fact that I moor in a super fund site, and the marine growth on the hull has far more interesting toxins in them than copper.

Edited by - on

Voyager
Master Marine Consultant

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Response Posted - 02/07/2010 : 16:11:20

Wow! Sounds like a pretty huge job.

Last year when I scraped (with a manual scraper) the bottom paint from Passage, I think it took me something like 4 weekends (8 x 8 hours) ~ 64 hours? to finish.

It was drudgery for sure, but I got to listen to all my Frank Sinatra, Tony Bennett, Steely Dan, Pat Metheny, Keith Jarrett and Bela Fleck CDs, as well as hours of other cool radio music.

And my biceps and triceps were rock hard by the end of the ordeal. I guess my respirator and headgear worked ok, because I'm still breathing and can generally write complete sentences! (there may be differing opinions on this among forum members however) ;->

Edited by - on

OJ
Master Marine Consultant

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Response Posted - 02/07/2010 : 16:55:08

David,

Thank you very much for taking the time to share all that you have above - you are very generous!

One of the big negtives with other blasting media is the mess you end up with. What are you experiencing regarding residual baking soda and paint?

That's pretty impressive progress you are making. You are removing VC17 only?

Edited by - OJ on 02/07/2010 16:56:31

delliottg
Former Mainsheet C250 Tech Editor

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Response Posted - 02/08/2010 : 18:00:30

Steve,
The baking soda simply washes away in the next rain, or you can hose it down. My truck looked like it'd gotten a light dusting of snow since it's the closest to the work, but other than that, it just seems to disappear. Of course we get a fair amount of rain here, so that helps.

The residual VC-17 has yet to show it's face anywhere, I've been looking for collections of blue on my boat's parking pad, but nothing so far. Obviously it's there somewhere, but VC-17's so thin, and the paint was fairly weathered that I'm not sure how much there would be in the first place. I haven't bothered trying to calculate the volume of paint on the hull, but I suspect that it would be substantially less than the quart we rolled on several years ago over the weathered coat that was already there.

I have found one hole in the fiberglass, it looks like something punched into the hull. It's sort of crescent shaped and smaller than a dime, so I'll be grinding it out and going back over it with Martex (I think?).

I'll take some pictures of the loading setup so folks can see what I'm doing there. First I have to build a muffler/air cleaner for my compressor, the noise is driving me crazy (and Rita). I talked to one of the friendly guys at my local hardware store and he told me how he'd built one for his compressor. Basically it's a 3/4" ell attached to a 1-1/2" reducer, 1-1/2" x 4" nipple & end cap. Drill holes in the end cap, stuff air cleaner foam into the nipple and screw it all together to make a muffler/air cleaner. We'll see how it works.

Edited by - on

delliottg
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Response Posted - 03/06/2010 : 21:05:24

So I learned something useful today & wanted to pass it on.

The soda blaster has been a pain since the day I bought it. It won't feed soda reliably, and it'd gotten to the point where I was ready to toss in the towel, return the blaster, and find someone to do it for me. I'd done all kinds of things to try to make it work properly to no avail, including polishing the draw tube to try to defeat clumping, I also tried a teflon wax product, as well as enlarging the holes. Nothing seemed to work. I had originally bought a 50lb bag of media, but had been using food grade baking soda because it was roughly half the price. I decided to give the actual blast media a try, and lo, my problems (mostly) disappeared! However, I went through 15lbs of media in something like 10 minutes (I'd slightly enlarged the draw tube holes earlier). I went through the media so fast, I thought there was something else wrong (again), until I lifted it. So I dialed it back (the blaster has a media gauge that'd I'd always had wide open, and the media lasted much longer. I also learned that I could mix in the food grade baking soda with the media to give me more media to work with. I did this by mixing them in a five gallon bucket (rolled it down my driveway a few times with the lid on).

I was able to get further in one day's work than I had in any two to date. I got half the keel cleaned off, and I'd say I'm approaching half way through, but now that I know how it works (after days & days of screwing around with it), I think the rest of the job will go faster. Now I'm mostly limited by my shoulder I think. Before it was so slow to do it was mostly just frustrating.

Now I'm out of media, so I need another trip to HF to get more.

Edited by - on

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