3M 4200 Vs. 5200: what’s the difference?

3M 4200 is a faster-curing multi-purpose epoxy suitable for small repairs on various materials including fiberglass, wood, tile, and metal. It can be disassembled after bonding. 3M 5200 is a slower-curing epoxy designed specifically for high-strength permanent bonding of wood, fiberglass, and metal components. It has over 3X higher tensile strength but cannot be disassembled after cure. However, for a skylight on a flexing surface, 3M 5200 is a better permanent option.

3M 4200 Vs. 5200

3M 4200 Vs. 5200: Specs & Uses

⏰Cure Time

3M 4200: 20 mins tack free, 15-24 hrs full cure

3M 5200: 4 hrs tack free, 24 hrs full cure


3M 4200: For small repairs only, not structural. Low chemical resistance.

3M 5200: Not for flexible substrates. Poor chemical resistance.

🛠️Common Uses

3M 4200 seals and bonds various parts in marine and RV vehicles; adheres to EPDM rubber pond liners; covers 3M VHB tape when installing solar panels on an RV to serve as a protective layer; below the waterline applications, commonly used by boat builders.

3M 5200 bonds galvanized sheet metal to an aluminum boat; bonding polyethylene in kayaks; attaching clear vinyl window to a Mazda Miata soft top.

Technical Info

3M 42003M 5200
Datasheet📥3M 4200📥3M 5200
Base PolymerPolyurethanePolyurethane
Solids Content100%97%
HardnessShore A 40Shore A 68
Tensile Strength1240 psi4800 psi
Max Continuous Temp190°F190°F

My Hands-on Test of 3M Marine Adhesive 4200

3M Marine Adhesive Sealant Fast Cure 4200
I have been using this boat-sealing material for a while now and have found it to be excellent at keeping water out of areas I want dry. I have used it on my class C RV to reseal the seam between the roof and cab-over, and it has worked perfectly.

I have also used it for many other sealing projects and have always been satisfied with the results.


I have also used this sealant to seal joints in an old wooden boat I was refinishing.

applying 3M 4200 on boat
applying 3M 4200 on the boat

Paint Over

If you need to paint over 4200, use a shellac-based primer. It works great, but it’s essential to properly prep surfaces to be bonded for the best results. The sealant is placed over the Dicor tape, putting the sealant inside the metal corner piece and secured back in place with screws. The sealant will be pushed out the sides, and then you smooth it out.

holding 3M Marine Adhesive Sealant 4200
holding 3M Marine Adhesive Sealant 4200

Worked great for boats

I must say that this stuff worked great for boats. I used it to seal up some holes I needed to drill on my outboard motor bracket, and it worked wonders. It’s ideal for anything where you need strong adhesion and sealant, and it can be removed if necessary after curing.

3M Marine Adhesive 4200 Explained

3m 4200 Cure Time

20 mins tack free, 15-24 hrs full cure

Will 3m 4200 cure underwater?

It doesn’t work on wet surfaces, though, so make sure your surfaces are clean and dry before applying.


One thing to note is that the tube of caulk did not come with a nozzle. Doing a return or refund was very inconvenient, especially when I purchased the caulk just in time to do a project. I had to start buying this kind of item elsewhere, which was frustrating.

3M Marine Adhesive Sealant Fast Cure 4200

💬 FAQ of 3M Marine Adhesive 4200

Q: Is it necessary to use 3M 4200 within 24 hours of removing the seal, or will it go bad?

A: If you reseal the product (remove and clean the nipple and put a nail or bolt in the tube opening), store it in a ziplock bag in the refrigerator, and take it out to reach room temperature before use, it can be used beyond 24 hours without going bad.

Q: Will 3M 4200 adhere to an (epmd) rubber pond liner and keep it flat?

A: This product should work as it remains flexible, but you may need to scuff up the surface for better adhesion. However, it may be better to consider an adhesive specifically made for epdm, which is used in roofing.

Q: Can 3M 4200 be used to cover some 3M VHB tape to install solar panels on an RV, and will it be strong enough without being permanent?

A: While 3M 4200 can be used to cover 3M VHB tape, it may not be the best choice for a permanent bond. The fast cure version of 3M 5200 is a better option for a stronger and more permanent bond.

Q: Will 3M 4200 work underwater, and how quickly does it set up?

A: 3M 4200 and 5200 are the best products on the market for below the waterline applications and are commonly used by boat builders. The regular cure time is 24 hours, but there is also a fast cure option.

CTA:list all comments

4 reviews

  • Greetings, I have an RV with a fiberglass roof and want to attach pre-galvanized strut channel to the fiberglass so that I can then attach solar panels to the strut channel via brackets. Many people on YouTube tend to use VHB tape to do this (for example http://tinyurl.com/ypgq7b2a Time: 19:30), but a few use 3m 5200. What would you suggest?…Read More

    • Hi Brad, I would recommend 3M VHB Tape. (You can see my article here: https://www.stickyaides.com/3m-vhb-vs-gorilla-tape/) It can withstand a wide range of temperatures, from freezing conditions to scorching hot summers exceeding 115°F. You can see how the solar panel is attached to an RV here:Read More

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My Hands-on Test of 3M 5200

3M 5200
I’ve been using the 3M Fast Cure 5200 for years, primarily on my boat. Whenever I drill a hole or put a screw into the boat’s hull or transom, this stuff is going on the screw threads or in the hole to seal it from water permanently. It’s pretty amazing stuff. I’ve even patched holes up to 1/2 inch in diameter using just 3M 5200, and I’ve never had a drop of water get in through that hole afterward. It’s a must-have for boats, keeping them afloat without any leaks whatsoever.

The only downside to the 3M Fast Cure 5200 is that it can be messy and not very reusable. Even the small tubes are expensive. However, if you cap it after using it, make sure you find a way to use the rest of the sealant in the not-too-distant future, as the cap will become difficult to remove, and the sealant will harden up near the cap. Despite that, 3M 5200 sticks to just about every type of material on the planet and is impenetrable to water.

3m 5200 fast cure how to apply?

I’ve used this stuff on my Smyth Ute car conversion, specifically to glue the plastic taillights to fiberglass. It worked wonderfully. The taillights are securely in place, and if I need to replace a bulb, I can carefully remove them by flexing them a bit and then reapply the product to resecure them.

3m 5200 works as a permanent seal for my boat drain plug housing
This adhesive is truly reliable.

3m 5200 Marine Adhesive Sealant On Aluminum

3M 5200 was successfully used to bond aluminum to fiberglass on an RV, which suggests it may work on HDPE. However, if the HDPE is thin and flexible, a more flexible adhesive may be a better option.

Moreover, I’ve also used 3M Fast Cure 5200 to glue in my plexiglass rear window on the car conversion. It provided a strong bond, and I’m on my second tube now. If anything, it’s almost too good!

3m 5200 Fast Cure Vs Regular

The fast cure develops only about 75% the of the “Overlap Shear Strength” of the standard 5200!

In my experience, I use 5200 for everything that needs a permanent bond. This stuff is truly amazing and well worth the price. Just make sure to clean the surface thoroughly before application and allow it to cure for a couple of days. Once it’s cured, you won’t have to worry about it coming free. I’ve used it on boats, and vehicles, and even repaired cracks in my shoes. I can’t say enough good things about it.

Is 3m 5200 paintable?

3M 5200 Marine Adhesive Sealant is sandable and paintable after it is fully cured. The problem with painting a flexible sealant like this is that, if the paint is not as flexible as the sealant, the paint will crack.

Another great aspect of this sealant is its flexibility. I recently used it to repair and seal cracks on my muck-style snake-proof boots, which I wear daily for work in swamps. It worked perfectly, remaining flexible and providing excellent adhesion. It’s a versatile adhesive that goes beyond just marine applications.

While the 3M Fast Cure 5200 is a fantastic product, it’s important to note that it’s permanent in most cases. So, if you’re looking for a more practical and easier-to-use option, consider using ‘4200’. It can be just as effective and offers more flexibility for certain applications.

3M 5200

💬 FAQ of 3M 5200

Q: Can I use 3M 5200 to secure galvanized sheet metal to an aluminum boat?

A: The effectiveness depends on the load. If you remove the patina from both surfaces and ensure there is enough bonding area, it should work. Make sure to secure the joint until the adhesive is fully cured.

Q: Is this adhesive suitable for repairing a 2-inch PVC pipe coupling underwater?

A: If the coupling is submerged and cannot be moved or drained, this would be your best option for repair. Clean and steel wool the surface before applying the adhesive. While I can’t be certain if this will solve your specific situation, I have been impressed with 3M 05220. It was specifically designed to stick to the fiberglass hulls of boats while they are still in the water.

Q: Does this adhesive work on polyethylene used in kayaks?

A: Yes, once it sets, it cannot be removed.

Q: Can 3M 5200 be sanded?

A: Once fully cured, it can be sanded. Keep in mind it may clog the sandpaper slightly. The quality of surface preparation determines how well the adhesive sticks and how finely you can feather the product.

Q: Will 3M 5200 effectively glue a clear vinyl window to the soft top of a 1997 Mazda Miata?

A: It is possible, but I would recommend consulting a professional installer. Keep in mind that using this adhesive may limit future options.

Q: Can I use this tube with a typical caulk gun used for regular window caulk?

A: I had the same concern, but the tube has an internal plastic plunger cup that a traditional caulking gun presses against. It is similar to a traditional caulk tube. The additional metal seal helps prolong the storage of the adhesive sealant until you are ready to use it. However, once the seal is broken, there may not be much shelf life left.

Q: Will this adhesive bond metal to a porcelain shower tile?

A: I have only used it for pool tile, and it was not effective for that purpose.

Q: Would you recommend 3M 5200 for gluing a rubber pad to a fiberglass paddle board used in saltwater?

A: Yes, I recommend roughing up the fiberglass with at least 120-grit sandpaper and cleaning it thoroughly with acetone to ensure a clean surface. Apply the adhesive to both the fiberglass and the foam, then use a thick piece of plywood over the foam and clamp it down to provide even pressure during the curing process. Be aware that once cured, it will be extremely difficult to remove the foam. This adhesive is permanent.