Follow the directions on the bottle. Make sure your coating system is mutually compatible and proper for the task at hand. Start everything with a thorough scrubbing with degreaser and a freshwater rinse. Then you must remove all scale and loose material including all the way to the bottom of any pits. Enrust needs light surface rust to react and bond. That means after you’ve sanded or feathered the interface, reapply fresh water to the area you’ve prepped and allow surface rust to form. Once thoroughly dry, generously apply well mixed (that has not expired or reacted) Enrust with a brush (not a roller) at 90 degree angles with about 20 minutes between coats. Allow to cure 24 hours. If you’re not satisfied with the appearance of the coat after 24 hours, reapply Enrust and allow it to cure again. Repeat until all traces of surface rust have vanished and an airtight epoxy is all that’s left exposed.
Once this state has been achieved, it can be left that way for some time and even exposed to saltwater. All that is required is to scrub the area with soap and water, rinse it clean and remove all residues, and reapply Enrust when dry. Once you begin priming you are committed to continuing though the final topcoat layer. Inadequately topcoated primer that has been exposed to salt spray must be completely removed and the process restarted. At no point in this process is anything resembling chemprime or Ospho to be utilized. I find that 2 coats of primer and 2-3 coat of paint applied under these circumstances are quite durable.
This process assumes that white blasting and the proper application of complete coating systems is not an option.
If they’re needle gunning and grinding properly then Enrust is a terrible product to put down. Enrust (Endrust, Endallrust, etc etc) only works when there is rust. And even then it’s just a lazy way out or there’s something prohibiting proper prepping. Using Enrust is usually just putting down a layer between your primer and steel. A non bonding layer when there is no rust.
Chem-prime (green, ospho type stuff) is different but should be used just to clean up.
When I started shipping twenty years ago the company I was with would simply paint rust. There’s always a chip or spot that appears and it would quickly be covered with paint. No prep, no needle gun or grinding. Just paint. There was almost no rust anywhere. Certainly no rust that lasts. It might have been one guy’s job to walk around with a paint can and brush once a week for a few hours.
Now I’m at MSC and they spend hundreds of man hours a week needle gunning and grinding with all sorts of preps and primers yet most MSC ships looks like turd stained rust cancers. I’ve tried to convince folks that weekly spot painting over new/small rust spots would save a lot of time and money but everyone here thinks I’m insane.
I’m now convinced that painting over small rust areas is vital preventative maintenance. It’s like greasing fittings. A few man hours a week greasing fittings prevents a lot of labor restoring and rebuilding a frozen block or roller later.
First give the area a quick fresh water rinse in the morning followed by spot painting in the afternoon. If after a while the area looks spotted go ahead and paint the whole area with topcoat. Do not grind off the old paint that had protected the metal all those years.
Once the rust on the whole ship is under control then repair any blistered areas. But keep up on the spot painting.
I know to most what you are saying is heresy but there is some truth to it. Rust needs moisture and air. If you paint over the first part you see you at least cut off the oxygen to that spot. Unless you can wire brush, prime , paint and give each layer time to cure properly according to the paint manufacturers recommendation you are doomed to failure on a large area. With a ship at sea it is practically impossible to follow manufacturers recommendations which include the environmental conditions. So, I agree with your approach. Cut off the air to the first sign of cancer until such time as you can get in a position to handle the problem properly. The AB’s can better spend their time doing other things. Geez…how many times have I walked past some needle gunning OS or AB only to not be able to properly dog a hatch because the bushings were worn out or not lubricated?
Stop the bleeding by applying pressure (put a spot of paint over the rust until the rust stops).
When the bleeding stops set broken bones and stitch the wounds (take a grinder or needle gun to any bubbles of rust).
Once the wounds are repaired cosmetic surgery may be used (paint over the area to make the area match or cut in sharp lines).
Now look at the photo below. This area was painted about two months ago. A tiny bubble of rust has begun. The time to address this is NOW (or a month ago) with a little spot of primer and then a little spot of topcoat. It would take two minutes. I’d bet if that were done soon the area would be nice a year from now.
Except they won’t paint that rust spot and a year from now it’ll be another turd stain rust cancer just like the thousand other turd stain rust cancers all over this ship. That’ll take a few days to fix then not to mention the loss of a little more steel.
When applied properly and allowed to cure fully, Enrust holds up pretty well and is very adhesive. If you have the equipment and opportunity to white blast and properly apply a complete system, more power to you, but you’re probably not underway. In my experience most problems with Enrust are the product of impatience and poor quality control. It adheres just fine as anyone who has ever gotten any on their hands or clothing can attest. It may not be a permanent system but it can certainly help in getting and keeping shipboard rust under control under realistic non-shipyard conditions.
I found that using less paint and more coats held up longer than any other process. Wait a good day after applying rust inhibitor Thoroughly agitate your paint feather your edges, apply two VERY light coats of primer followed by at least two light coats of interthane
In the way-back machine, I had the best result with ospho after getting the rust gone. Preferred wire-wheel unless they were bustin’ scale rust. Washed with fresh water, then 2 coats of primer, then 2 top coats. I made a bet with the bos’n over the fresh-water part. He said the water didn’t matter. We painted to identical parts of the deck - same exposure to crap. He agreed, water made the difference.
Wouldn’t it be best to quickly hit that tiny area with the edge of a wire wheel and get the rust out, then prime it and paint it? Add 5 minutes to the job (including getting the wire wheel and extension cord) and should prevent future rust scale.
(That spot was probably the result of an imperfect top coat.)
The first thing to look at is the Enrust application and making sure you’re following the directions precisely. Two coats 20-30 minutes apart then 24 hours cure time before overcoating.
Next, make sure you’re using enough coats of primer and paint. Rolling on will likely require twice the recommended coats of each because you can’t roll on as think as you can spray on, minimum of two coats of each and maybe three of top coat. Make absolutely sure the the top coats have no holes in them to allow moisture in, frequently two contrasting colors are recommended so you put the first coat in one color, making sure you can’t see any primer through that, then put the final coat in another color, making sure you can’t see any of the previous coat through little holes.
the last rig I worked on was made from such poor steel it had already had the decks grit blasted and new paint scheme within 3 years I was on for years 4-5 and it was happening again.
The rust was coming from inside the plate.
It was meant to last 10 years, crew didnt think so
IMHO needle gun will trap contaminants into the surface so its never really clean
Yeah, rig builders used to buy the cheapest crap they could find to build a rig. Rig buyers were happy, they knew what was going on. Drillships and MODUs are disposable by design and the buyers know that when they sign the build contract. Low bidder gets the contract, minimum specs for steel, valves etc… Just enough to get out of the yard. Then they pay out the wazoo for drilling equipment but expect it all to be maintained by a minimal crew and do UWILD instead of shipyard. Been like that for years.