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Author Topic:   Marikate On - Off Application?
bkoelbel posted 09-11-2001 07:38 AM ET (US)   Profile for bkoelbel   Send Email to bkoelbel  
Has anyone had experience with this product to remove the yellow / brown scum line that inevitably shows up towards the end of the season?

Must the boat be on the trailer, or can it be done in the water?

How long must the substance stay on the hull?

What do you do with the residue?

Please advise, thanks.

kingfish posted 09-11-2001 03:43 PM ET (US)     Profile for kingfish  Send Email to kingfish     
I have used On-Off on my Outrage 22 and I can tell you it is incredible! It really does a remarkable job of getting *all* that stuff off of fiberglass and does not damage the finish in doing so. *DO* follow the directions - it is really strong stuff. Cover your trailer with visqueen (take my word for it, just keeping the trailer flushed with water is not good enough), wear rubber gloves and avoid the fumes. The instructions are clear, just follow them and you'll be happy with the results.


kingfish posted 09-11-2001 03:46 PM ET (US)     Profile for kingfish  Send Email to kingfish     
Didn't answer all your questions - The instructions indicate how long to leave it on - only a minute or two is usually enough.

I don't see how you could apply On-Off while the boat is in the water.

I just flushed the residue away into the lawn with a garden hose.


bkoelbel posted 09-11-2001 04:44 PM ET (US)     Profile for bkoelbel  Send Email to bkoelbel     

What is visqueen?

Taylor posted 09-11-2001 06:11 PM ET (US)     Profile for Taylor  Send Email to Taylor     
Trade name for plastic drop cloth.
Bigshot posted 09-12-2001 09:36 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
If you have a galv. trailer it will turn it white. Aluminum it does not affect. I use it in a spray bottle and by the time you spray down one side it is ready for rinsing. Stuff is mint but fumes can kill.
kingfish posted 09-12-2001 09:43 AM ET (US)     Profile for kingfish  Send Email to kingfish     
I now have a white galvanized trailer...(that's why I know that just flushing with water isn't enough)

sadder but wiser,


Bigshot posted 09-12-2001 11:36 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
It is still galvanized, don't worry! If you spray it on it usually does not drip or turn trailer white.
lhg posted 09-12-2001 07:14 PM ET (US)     Profile for lhg    
I have used Starbrite's Instant Hull Cleaner, put in a spray bottle, and my trailer is NOT white. Maybe it's oxalic acid content is not as strong as this other product, but it does clean the hull. Just rinsing any drips off the trailer seems to work.

I usually do not spray it directly on, however, as I have discovered just spraying it onto a rag, then wiping, does the trick. It takes a few minutes to do it's work removing the hull stain. I only spray areas I can't reach by hand.

LKS posted 09-12-2001 07:26 PM ET (US)     Profile for LKS  Send Email to LKS     
Good to know that this product works as advertised. Their canvas waterproofing works wonders!
kingfish posted 09-12-2001 09:21 PM ET (US)     Profile for kingfish  Send Email to kingfish     
On&Off has Oxalic acid, Phosphoric acid and Muriatic (Hydrochloric) acid - I've thought it was the Muriatic that powdered my galvanized finish, but I don't know for sure. Like Bigshot says, it's still galvanized, but it looks like it's been exposed to white paint overspray.

I have also gone to a spray bottle. This stuff is so strong, volatile or something, that if the humidity is pretty high there is very obvious "smoke" that comes out of the bottle when you take the top off! I suppose I am making it sound like this stuff is too ugly to work with, and I don't mean to. Follow the directions and it does one heck of a job. It is *the* product for really heavy crud, scum, algae, etc. Keep it away from the stainless though, or it will be turned black.

lhg posted 09-12-2001 09:52 PM ET (US)     Profile for lhg    
Kingfish: It sounds like the On-Off Product is too strong. It seems unlikely that anything other than Oxalic acid would be needed.

I'm a great believer in working up the ladder in cleaning chemicals or hull polishing abrasives, beginning with the weakest. Give the Starbrite's a try next time. LimeAway also works, especially for cleaning the water spotting deposits off engines.

Another product I've found for water line yellow stains, especially if left on the hull too long and dried, and not removable with the Starbrite's, is Sudbury HD fiberglass cleaner, a non-abrasive oxalic acid powder.
Works very well.
For all of this, I am not talking about actual marine growth here, only the yellow staining

Bigshot posted 09-13-2001 10:05 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I have been using on/off for about 15 years now nad only once did I burn my trailer(1st time I used it). I dripped the stuff all over the place and it left a few white marks. Since using a spray bottle9less waste and better coverage), no problems. Just watch how you breath in the fumes.
JDH posted 06-27-2003 12:09 PM ET (US)     Profile for JDH  Send Email to JDH     
Hey -

Dredging one up from the archives....

Can you use Muriatic Acid in a spray bottle? Sounds like a recipe for disaster....

I use phosphoric all the time for pickling steel, but I wear gloves and a respirator....


Bigshot posted 06-27-2003 01:56 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I use muriatic but not in a spray bottle. Watered down I bet would work.
RCS posted 06-28-2003 10:28 PM ET (US)     Profile for RCS  Send Email to RCS     
I've had pretty much the same experience as kingfish with the MaryKate On-Off. Works great but cover your trailer. Also, it seems to work best if the hull is dry when you spray this stuff on. There was no rubbing required at all.

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