3M's 5200 Adhesive/Sealant

[SS MAYFLOAT]

I'm in the process of redoing my transom (see boat restoration thread). Last year I installed a thruhull fitting using the 5200 as recommended by the expert help on this site. This stuff was a bear to get loose to remove my fitting for the repair.<br /><br />With it being so tough, but flexible somewhat, would this be good to bond my marine plywood to the hull in the transom? I would cover the wood and end grain to prevent water intrusion. Of course after the cure period I would glass in the new wood bonding it to the hull. I'm just thinking that the 5200 could give a better stronger bond than using epoxy or polyester resin. <br /><br />Open for suggestions.....thanks.........SS

 

[DJ]

Re: 3M's 5200 Adhesive/Sealant

SS,<br /><br />I wouldn't use 5200 for that. The resin or epoxy is a better idea. <br /><br />The latter will allow you to cover and saturate the whole backside thus sealing the wood.

 

[SS MAYFLOAT]

Re: 3M's 5200 Adhesive/Sealant

After thinking about it DJ, your right on. The 5200 would keep the moisture out, but if the moisture got into the wood somehow, the bond would be gone due to the inability for it to soak into the woods grain like the resin would. I do know that the first layer of laminate had to be chiesl'd off practically. That shows how the resin did soak into the wood fiber. <br /><br />With the size area I'm doing, I need something that has a moderate pot life. What would you suggest?

 

[DJ]

Re: 3M's 5200 Adhesive/Sealant

SS,<br /><br />I've used both, with success. You can "adjust" pot life by adjusting the catalyst-somewhat. Ambient temperature falls into the equation also.<br /><br />I would check out the products from West Systems. They have allot of info. available.

 

[hazben]

Re: 3M's 5200 Adhesive/Sealant

ss, I used the 5200 to bond 2 pieces of plywood together about a month ago. I then screwed it together and parked the truck ontop of it for a day or two. I still was a little disapointed with the results. The 2 pieces seemed to be separating a little. This may have been due to the plywood still being a little moist.

 

[DJ]

Re: 3M's 5200 Adhesive/Sealant

5200 wasn't designed for that purpose.<br /><br />For bonding wood together, nothing works better than Gorilla Glue.

 

[SS MAYFLOAT]

Re: 3M's 5200 Adhesive/Sealant

Okay DJ, next question. You mention Gorill Glue. My transom has two layers of 3/4 ply. One extends the whole length of the beam while the other is centered over the outdive area. It is about 4 feet wide vs the 8' piece that goes in first. <br /><br />Would it be best if I glued the two layers together first with Gorilla Glue and then bond them to the hull with the epoxy?

 

[DJ]

Re: 3M's 5200 Adhesive/Sealant

SS,<br /><br />Absolutely.<br /><br />It also won't hurt to run some stainless screws in there to help hold it together during the drying process.<br /><br />After you squirt the glue on, brush it out to get 100% coverage.

 

[SS MAYFLOAT]

Re: 3M's 5200 Adhesive/Sealant

My first plan on joining the two together was using exterior contact cement. Bad part on that is if the two pieces are not aligned up and it makes contact, its too late. That would be an expensive screw up for sure.<br /><br />Thanks again for the help and advice. It is always appreaciated so much.

 

[Chief101]

Re: 3M's 5200 Adhesive/Sealant

SS, to add to what DJ said, if you're going to use the Gorilla glue mist the plywood with water before applying glue. Polyurethane glue really likes the water and will follow it right into the plywood for a stronger bond. This glue expands so mechanical clamps of some form is necessary. I would use a lot of screws and some cramps. You can always remove screws and fill the holes later. Chief

 

[SS MAYFLOAT]

Re: 3M's 5200 Adhesive/Sealant

Right on Chief. I do woodworking as a hobby and have plenty of clamps. To bond the ply to the hull, I have made up some jack posts to push against the cabin bulkhead to the transom. Plus all the mounting holes for the swim deck and other hardware, I can use them to help clamp it to the hull as well to get a nice tight bond.<br /><br />My old shop teacher always said it isn't the glue that holds things together, it is atmospheric pressure. The glue is there to keep the atmospheric pressure out of the joint. So the tighter the fit, better the bond.

 

[Stratocaster]

Re: 3M's 5200 Adhesive/Sealant

My old shop teacher always said it isn't the glue that holds things together, it is atmospheric pressure.

Your old shop teacher should have taken high school physics!