What is a good clear sealant?

Hi Westend,

Just curious, were you using the good quality 100%, exterior grade, clear silicone calk? I would agree lower grade semi-silicones do not provide good performance (or ones not designate for exterior use), but the calk I buy from Lowes is 100% silicone, exterior grade and I think has a 5+ yr warranty if I remeber correctly? I'd have to check. Not to say I'd trust it that long, I still reccomends checking all calk joints several times per year regardless of what you are using. The calk I use has good resiliance to weather. I have no complaints with it.

I use a variety of sealants in my work life, including the best GE 100% silicone money can buy. I've used it for years and know the properties. I don't use it for sealing anything exposed to exterior weather. Today, there are a variety of sealants that outperform silicone and will not degrade from UV. The urethane caulks are good sealers for everyday mundane tasks like siding joints and household use. I use acrylics when painting because of fast dry time and good paint bonding. Geocel, parent company of Proflex RV makes different sealers for mobile applications. Their tripolymer sealants have the characteristics that we want in an RV sealer, good bond, high elongation rate, and durability. You definitely should not take my word as gospel, experiment for yourself. Take pieces of aluminum and put beads of different caulks onto them. Put it out in your backyard for a couple of years and go back to see what has occurred.

Agreed, Proflex is not what you use on your rubber roof, Dicor Lap Sealant is what should be used there... As far as walls go, if you like using silicone go for it. I personally wouldn't trust it, it just doesn't hold up on rv's. I have spent years rebuilding water damaged rv's and 9 times out of 10 most leaks are caused not by the type of top sealant people use, but because the trims,vents etc have never been removed to replace the dried out butyl under them. Usually the first reaction people have to a leak is to caulk or silicone the area when really the area needs to be taken apart dried out and completely resealed. An rv's top sealants should be checked yearly and trims, windows, vents etc touched up as necessary. At around the 7 year mark you need to completely re seal an rv, if you want it to last.. This means removing windows and trims, vents, access doors etc and remove and replace the butyl then re apply the top sealants using whatever makes you happy, again I recommend Proflex on the walls and trim and Dicor on the roof membrane.
In my opinion an rv is an expensive investment, why cheap out on maintaining it....

High quality 100% pure silicone will do fine on the sides of trailers and openings.

Silicone will not do as well as Proflex though. Silcone many times tends to peel or raise around it's edges. Proflex does not tend to do this. Proflex is very difficult to remove once cured; as silcone is usually much easier. I also don't recall seeing Proflex subjected to mold as quickly as silicone.

Silicone on EPDM or TPO will not hold up. (nor is Proflex recommended) The silicone will appear cured and dry, but it will peel right off showing that it never fully cures to that surface. Larger amounts will still be soft just as it came out of the tube.

Silicone on sides: ok and cheap cost

Proflex on sides: expensive, but more permanent, it also shows better long term, and I believe it tools better when applying.

+1 for Proflex

Silicone is an excellent sealer and adheres very well. Anyone that has worked with aquariums knows the tremendous pressures that a high quality silicon sealer will withstand.

The nature of travel trailers is that the joints tend to move a lot and pretty much every trailer will eventually need to be resealed. If the old caulk that needs to be resealed is silicone based it will have to have every trace removed before a new caulk will adhere at full strength. Removing every trace of old silicon caulk is a very labor intensive task. This is why silicon caulk is discouraged for RV exteriors. It is not that silicon won't adhere well it is because new caulk (even new silicone caulk) won't adhere well to surfaces where silicon has been previously unless the surface has been impeccably prepped.

RV repair facilities don't care if they are creating an eventual maintenance nightmare. They just do what ever is quickest, cheapest and takes the least amount of brain power.

westend wrote:
I would suggest that anyone thinking about using silicone sealers should put a small bead on a surface and let it sit out in weather for a couple of years. I think you will find that it deteriorates with age and UV exposure. It's an excellent sealer when used between two surfaces held in compression (like metal to metal covers and such). My experience is that it won't stand up to weather exposure.

Hi Westend,

Just curious, were you using the good quality 100%, exterior grade, clear silicone calk? I would agree lower grade semi-silicones do not provide good performance (or ones not designate for exterior use), but the calk I buy from Lowes is 100% silicone, exterior grade and I think has a 5+ yr warranty if I remeber correctly? I'd have to check. Not to say I'd trust it that long, I still reccomends checking all calk joints several times per year regardless of what you are using. The calk I use has good resiliance to weather. I have no complaints with it.

I calked around all the windows and side wall penetrations on my 89 Layton in October last year when I purchased it and we had an extremely bad winter last year and all is still well adhered.

The other thing I fogot to mention is (I'm not sure about Pro-flex) but silicone is very sensitive to age, IE, if you have it for 12 months, whether opened or not, throw it away and buy new. I've had older, good grade silicone have horrible adhesion and actually would not cure properly before I learned my lesson the hard way! (clean all off and re-do!)

Again, just my .02 for whatever they are worth.

I would suggest that anyone thinking about using silicone sealers should put a small bead on a surface and let it sit out in weather for a couple of years. I think you will find that it deteriorates with age and UV exposure. It's an excellent sealer when used between two surfaces held in compression (like metal to metal covers and such). My experience is that it won't stand up to weather exposure.

Gaffer222 wrote:

donn0128 wrote:
The only clear sealants I know of are silicone, and silicone is so NOT recommended for use on an RV.

Not recommended by who? Many manufactures use silicon sealant as well as dealer service departments. I have never had an issue using silicon on my campers.

You will get lots of differing opinions on Silicone use on TT's. Many say avoid it at all costs, don't use it, it won't adhere, Etc.

To each their own. I'm not suggesting the calks that others mentioned are not good, because I believe they are (I have no experience with them).

I would not use silicone on a roof, I like DiCor Lap Sealant for roof work, but I do use silicone around windows, compartment openings, and such. The key in my opinion is to spend the extra money for 100% silicone and not others that are not 100% silicone. I find it to have good adhesion, if the area being calked is cleaned/prepped properly before you apply the calk.

The other item that I feel is important is you can't simply "calk it and forget it" either with silicone or other products. Several times per year I check all my calk joints on the roof and windows, or any where I have applied calk to ensure it's still well bonded, if any is quesionable I scrape off and re-calk.

The key to longevity in these rigs is keeping the water out of them. If you can accomplish that, they will last a long time.

I'm not suggesting silicone over Proflex either. I find it provides good performance for me (again the good quality 100% exterior grade clear silicone) so I use it, but it may not be for everyone.

These are just my opinions of course, others will disagree and that's perfectly ok with me.

donn0128 wrote:
The only clear sealants I know of are silicone, and silicone is so NOT recommended for use on an RV.

Not recommended by who? Many manufactures use silicon sealant as well as dealer service departments. I have never had an issue using silicon on my campers.

I used Proflex RV on my Roadtrek last month. Actually my son did it. He used dish soap on his fingers to smooth it out. It was a little difficult to reach all the areas around the frameless windows. But, I am very satisfied with the results.

Use Proflex.....