3M 5200

[thomashoebus]

I had a crack in the joint deck - stern of my boat.
I grinded out the old compound from the crack (some polyester compound) and filled it up with 3M 5200.

The seem is 3 cm deep and 6 mm wide. I did the job last week so it's not to warm anymore. I find that the 5200 is drying very difficult since its should be fully hardened after 4-7 days. I contacted 3M and they couldn't really give an answer just that the 3-7 days was in 21 degrees celsius and a seem of 3 mm. And that it would take a longer time perhaps more than 2 or 3 weeks nodody knew.

Has anybody has any experience with this product under these conditions.

I have also another question the compound stays flexible but is sandable according to the specifications. How should i understand this is it as hard as polyester and can be sanded like polyester when it's fully hardened?

 

[beneteau_305_553]

3M 5200 is a pu flexible adhesive. It cures to a rubber material that can be sanded and overpainted with a flexible paint but it will never harden like a polyester resin filler which are hard but also brittle.

Provided you didn't smooth it off with white spirit or such like it will cure at 1mm depth per hour at 20 C. Additional heating such as a hot air gun may be required to get the material to 20C

 

[thomashoebus]

i assume you're meaning 1mm per day at 20C?

 

[SvenglishTommy]

Hi oceanis,

That is a very large gap to be filling with 5200, however, it should be fine as long as your're not expecting any structural adhesive qualities from it (there will be a lot of flexibilty in the join at that thickness).

As HunterWander says, it will always be rubbery in consistency, but can still be sanded when cured. I will contact our labs in Austin tomorrow and see if I can find out the curing time for that quantity.

Regards,

Tommy (3M)

 

[thomashoebus]

Thank you, the gap is exactly the same size as the thickness of the original polyester compound. I don't need structural quality at that place. Just keep the two pieces together and the joint has to be watertight. The deck is glued and screwed together to the hull by the toe rail. Aft of the toe rail there are no structural forces anymore on the joint just probably a little movement off the hull 2 feet behind the toe rail.