Sealant

[Nan]

Has anyone ever used 3M Marine Adhesive Sealant 5200 Fast Cure White 06520?  Thanks, Nan

[mossemi]

Yes, I have used it to attach hooks to the inside of the closer door and PVC boards to the inside of the lower hull.

 I think it is expensive and wasteful because the tubes dry out very fast.  I also think the package say it is permanent.

What are you going to use it for?

Mossey

[SeaDawg]

Nan, 5200 is more of a very powerful adhesive than sealant, and extremely  difficult to remove if you ever need to. (We've had to remove several items on our boat bonded with 5200, and it's a very difficult and time consuming process.)

What are you trying to do? If you're looking for a sealant, (caulk) you need to be looking at another choice.

Edited June 12, 2020 by SeaDawg

[Nan]

I thought it was a good idea, but I am wrong.  I was going to re-caulk the Oliver sign on the back of my camper for starters.  Then use it for anything else that leaked. My grandson already caulked the Oliver sign once (found it leaking on our maiden trip a couple of weeks ago), but he did not know that he had to remove the old caulk so he just caulked over it.  So, I was just trying to find a caulk that would last a long time and I thought this one would do it.  

 

[SeaDawg]

5200 is great if you know you will never, ever have to remove it. It can't be removed mechanically without ruining something ( not just your day). One or both parts will break, bend, or deform . Chemical removal is possible, and tedious. There used to be a joke in the marine world that you could pick up your boat by any part fastened and sealed with 5200, as long as the part was strong enough.

3m 4200 is easier to remove, but not simple, either. 

I don't know what sealant is under what your grandson applied, but if it's silicone, it needs to be removed, (his and the original), and cleaned, to allow a new sealant to adhere. As wonderful as silicone is, it doesn't like to adhere to itself .

Sherry

Edited June 12, 2020 by SeaDawg

[John E Davies]

I use this for all external sealing, it is excellent, stays white and is UV resistant, and you can remove it. The 5200 is for stuff like bonding the deck to a boat, a “forever” job that you hope to never ever do again.

3M 4000 UV Fast Cure

I tape around the job, work the sealant in with a finger, then take the tape off. It looks great if you take some extra care. For some pics, look here: .... https://olivertraveltrailers.com/forums/topic/2082-how-to-install-a-big-bubble-level-no-drilling/

John Davies

Spokane WA

Edited June 12, 2020 by John E Davies

[SeaDawg]

I'd have to agree with John. I  think we used 4000 the last time we did the light. It's not an easy product to use for people unaccustomed to sealing. And, it's expensive in the small tubes.  But in sealants, you often get what you pay for. It's uv resistant, remains flexible for a long time (our hulls do have flex as they travel, just like boats), and is mildew resistant.  

Whatever you choose, make sure old caulk and residue is removed mechanically  (scraping, peeling), then chemically (I'd probably do mineral spirits or goo gone first, then denatured alcohol or acetone as a cleaner) so the pores are clean.  Sealants are only as good as the prep. 

Though we used a 3m product last time, I may look at a Sika product  next time. I've used a lot of sika products building and maintaining our home, and I  really like them. Unfortunately,  they're not available in small tubes like 3m. 🤔

Another note, don't expect opened tubes of sealant to be good six months later, even if you cap them. That's why the little tubes are popular.  Exposure to air degrades effectiveness for most sealants. They start to "cure" in the tube.  Buy the size you need, or be prepared to discard the remainder. And, check whatever you buy for expiry date. 

I'm not a big silicon fan, but it's generally a much easier product to work with and remove later for renewal than the 3m adhesive sealants . My husband is a fan of silicon products,  so, we have this discussion from time to time.😁

Anyway, here's some info from Practical Sailor, one of my most trusted sources for all things fiberglass. Enjoy.

https://www.practical-sailor.com/boat-maintenance/caulks-versus-mildew

Sherry 

PS thank goodness you have a grandson who is willing and able to help you. That is so sweet. God bless him.

S

Edited June 12, 2020 by SeaDawg
Typos and clarity