Sealants and Caulks: What are the proper ones to use and where?

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Sealants and Caulks: What are the proper ones to use and where?

June 30, 2011, 08:25:05 am

Every now and then I read here and on other forums about how and where to use certain types of caulk: latex, butyl, silicone.

It would be useful to many of us to be able to search the archives and find one thread dealing with this topic. So, what kind of caulk or sealant do you use for specific applications?

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #1 – June 30, 2011, 10:10:42 am

George, I used to make caulk in my first Oklahoma plant. To me the answer is very simple. Use urethane caulk wherever possible like Dicor or Sika NP1. It comes in self leveling and high modulus, no sag versions. There are other brands but these are the most easily obtained. Buy at Lowes/Home Depot or RV supply stores.

Urethane caulk is very flexible. It is chemical and UV resistant and is a very good adhesive. Use silicon only when clear is needed but don't rely on its adhesive capabilities. I have no use for butyl or latex/acrylic on a moving structure like an RV.

Caulk should be applied where the depth of the joint is 1/2 the width of the joint, ie a 1/4" joint should be only 1/8" deep.

FWIW

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #2 – June 30, 2011, 10:21:41 am

I agree 100% with Kent. A lot of people swear by Silocone seal but it is one of the last ones to use. It is amazing how water can get behind it and you think it is doing a good job, only at a later date to see black mold lines behind it and you say "how did that get there"?
You do not want to be re-caulking every year on an RV so use the correct stuff at the start, and if it is needed to caulk a joining strip for instance, first take it off, clean it well then run a bead of Urethane down joint then replace trim. Do not just bead the outside. This will stay good for a long time. Save the silicone for places were it can be removed easily and re-done ie around sinks etc. (and use the smallest amount possible--daubing tons on does NOT make a better seal)

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #3 – July 01, 2011, 08:58:10 am

The resources on this forum are truly amazing. Ask about caulk and a former manufacturer of caulk pops up!

Kent, years ago I discovered a polyurethane adhesive caulk called 3M-5200. The cure rate is abysmal, but I tend to use it when I am really serious about sealing something. Can you tell me where, in the grand scheme of caulks, it falls? Is it related to the products, Dicor or Silka, that you mention? Is there a similar product that is easier to find in regular building supply stores or RV stores?

Thanks, Richard

Re: Sealants and Caulks: Whats the best and easiest way to remove old sealant

Reply #4 – July 01, 2011, 10:09:22 am

Anyone got any great solutions to this issue ? I find that removing the old stuff is much harder then applying the new sealant.

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #5 – July 01, 2011, 11:30:44 am

3 in1 painters tool and heat gun used very gently.

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #6 – July 01, 2011, 12:42:39 pm

Kent, are urethanes and polyurethanes the same thing? Sika's website has a lot of information, but I don't see NP1 as a product. They have Sikaflex, an all purpose polyurethane, would you recommend that?

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #7 – July 01, 2011, 01:36:24 pm

Quote from: Jan & Richard Witt – July 01, 2011, 08:58:10 am

The resources on this forum are truly amazing. Ask about caulk and a former manufacturer of caulk pops up!

Kent, years ago I discovered a polyurethane adhesive caulk called 3M-5200. The cure rate is abysmal, but I tend to use it when I am really serious about sealing something. Can you tell me where, in the grand scheme of caulks, it falls? Is it related to the products, Dicor or Silka, that you mention? Is there a similar product that is easier to find in regular building supply stores or RV stores?

Thanks, Richard

Richard, regrettably I am not familiar with the 3M 5200 Marine caulk. After looking at the MSDS and Tech Data Sheet it appears to be an epoxy/urethane which would give it better than average adhesion characteristics and retain the cohesive strength and elongation of a urethane. I used to manufacture several products for 3M and their standards for the vendors were exceptionally high so its probably very good material. An epoxy/urethane would be designed for any situation where one needed a combination glue and sealant such as sealing lap strake on a wood boat.

Dicor and NP1 are more general use, architectural caulks and adequate for most of what we would do to our motor homes. They too have good adhesion and probably even better elongation. One word of caution, do not necessarily go by what FOT parts recommends or sells you. I have asked them about caulks several times at the plant and they have no idea what to use where in the parts department. The last time I was at the plant they sold me an black caulk called 626 that took weeks to loose it tackiness and has never really cured. I should have read the label like Peggy always tells me before I used it but that's almost as bad as reading directions.

The two industry terms that you should be familiar with to talk caulk are:
High Modulus - This is non-sag for vertical applications
Low Modulus - This Self Leveling caulk for horizontal surfaces

You mentioned that 3M 5200 was very slow curing. Most urethane and epoxy/urethane caulks are moisture cured. They grab the humidity from the atmosphere to initiate the chemical reaction that cures the product. If you use them in a very dry environment they take forever to cure. However, a surface cure can be sped up by spraying a light mist of water over the caulked joint. There are also urethane caulks available with accelerators for use in very dry areas. I noticed 3M 5200 has a fast cure available. If a quick cure is required and you are in an arid area, thoroughly research which caulks will cure in the humidity at hand otherwise it could take days for the caulk to cure enough that you could move your coach without damaging your newly caulked joint.

There is a product I purchased from a mobile RV technician called ProFlexRV manufactured by Geocel in Elkhart, IN. Like 3M, they hide what the foundation polymer really is but I have used it and it worked great. The RV technician swore by it. It has many attributes that make it very forgiving for the average user. I can't recommend it based on it s chemistry because I don't know what it is made of but I would buy it again. It can be purchased online at http://www.geocelusa.com/php/retail/product.php?prdb_product_id=39. I have no affiliation with this company.

The bottom line is that knowledgeable architects and engineers specify urethane over acrylic and silicone caulk because it adheres to most surfaces, it has good chemical resistance, good UV resistance and does not become dry and brittle over time. I hope this helps.

Quote from: Dick S – July 01, 2011, 12:42:39 pm

Kent, are urethanes and polyurethanes the same thing? Sika's website has a lot of information, but I don't see NP1 as a product. They have Sikaflex, an all purpose polyurethane, would you recommend that?

Dick, yes urethane and polyurethane are commonly used for the same polymer. Regarding NP1 I made a mistake Its been 12 years since I was in the caulk business. NP1 is actually a Sonneborn product it is not made by Sika. Sika makes Sikaflex 220 and 221 as I recall. Sonneborn and Sika are leaders in the construction industry sealants and Dicor and Geocel are leaders in the RV industry sealants and make reliable products IMHO.

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #8 – July 01, 2011, 02:03:23 pm

Richard,

3M 5200 Marine Caulk is used extensively in the pleasure boat manufacturing process to seal the hull to the deck. Many times this is backed up with screws on about 6 inch centers. Once cured, separating the hull from the deck is impossible with incurring damage to the seal surfaces.

If you use it, be sure you never want to separate what ever you have joined.

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #9 – July 01, 2011, 05:49:22 pm

Kent, Thank you, this has been very helpful and enlightening'

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #10 – July 02, 2011, 12:02:51 am

Quote from: Rudy – July 01, 2011, 02:03:23 pm

Richard,

3M 5200 Marine Caulk is used extensively in the pleasure boat manufacturing process to seal the hull to the deck. Many times this is backed up with screws on about 6 inch centers. Once cured, separating the hull from the deck is impossible with incurring damage to the seal surfaces.

If you use it, be sure you never want to separate what ever you have joined.

An RVing friend who used to be in the boat building business related one experience with 3M 5200: They were removing deck railing which had feet (similar to the attachments for our rear ladders) screwed to the deck with 5200 underneath each. They removed all the screws and were using a crane to try to remove the railing from the deck. Instead, the crane lifted the entire 35' boat off its blocks. They had to cut the 5200 from under each foot with a knife. Strong stuff!

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #11 – July 02, 2011, 12:30:33 am

If 3M-5200 can lift a boat it sure can hold a solar panel bracket to the roof.

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #12 – July 02, 2011, 08:52:55 am

Quote from: Barry & Cindy – July 02, 2011, 12:30:33 am

If 3M-5200 can lift a boat it sure can hold a solar panel bracket to the roof.

I agree, presuming the 5200 is attached to a sound substrate. As you mentioned in a previous post, if your roof is painted you will be relying on the adhesion of the paint to the gel coat for strength.

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #13 – July 02, 2011, 09:23:35 am

Kent is right. A number of years ago I had bedded the windlass on the bow of my aluminum boat with 5200. When I later needed to remove it, I removed the four five-eights bolts but the windlass was still attached strongly enough to still perform its function. I was eventually able to pry it up by forcing a putty knife under the edges. When it finally did come up, the bond had been broken between the paint and the etching primer.

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Sealants and Caulks: What are the proper ones to use and where?

June 30, 2011, 08:25:05 am

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #1 – June 30, 2011, 10:10:42 am

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #2 – June 30, 2011, 10:21:41 am

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #3 – July 01, 2011, 08:58:10 am

Re: Sealants and Caulks: Whats the best and easiest way to remove old sealant

Reply #4 – July 01, 2011, 10:09:22 am

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #5 – July 01, 2011, 11:30:44 am

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #6 – July 01, 2011, 12:42:39 pm

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #7 – July 01, 2011, 01:36:24 pm

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #8 – July 01, 2011, 02:03:23 pm

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #9 – July 01, 2011, 05:49:22 pm

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #10 – July 02, 2011, 12:02:51 am

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #11 – July 02, 2011, 12:30:33 am

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #12 – July 02, 2011, 08:52:55 am

Re: Sealants and Caulks: What are the proper ones to use and where?

Reply #13 – July 02, 2011, 09:23:35 am

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