Easy removal of excess Silicone

[Iflyfish]

Excess Silicone removal

 

I found plastic and razor blade scrapers not up to the task of removing excess, hardened silicone sealants. I decided to go with a harder blade and it works great. Pic attached.

Box cutter

https://www.amazon.com/Stanley-10-099-Classic-Retractable-Utility/dp/B00002X204/ref=sr_1_30?keywords=box+cutter&qid=1566854434&s=gateway&sr=8-30

 

Blades

https://www.amazon.com/WORKPRO-Utility-Blades-Dispenser-100-pack/dp/B015W3AKDQ/ref=sr_1_5_sspa?crid=3CG4TE1NY7OU7&keywords=stanley+10-777+fatmax+locking+retractable+utility+knife+blades&qid=1566854616&s=gateway&sprefix=Stanley+Retractable+Utility+Knife+blades%2Caps%2C520&sr=8-5-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFUU0xFR0RVNkVSNkUmZW5jcnlwdGVkSWQ9QTAxODU0MjkyRUY5Q0xJTzJWVVE3JmVuY3J5cHRlZEFkSWQ9QTA0OTA5MTgxVDhWN0JKRURUMzY2JndpZGdldE5hbWU9c3BfbXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

 

Scraper Handle

I found the yellow handle at Home Depot

[jjrbus]

Sillycon the bane of used RV buyers.   Unfortunately the term silicone is used as a generic term for caulk.

Even after removing what looks like all the silicone there is still a residue that nothing will stick to.  If I am going to recaulk an area I sand it to mechanically remove as much of the caulk as possible to avoid failure.

[AtlantaCamper]

I have recently realized the evils of silicone based sealants.  I have vowed, "No more silicone" on my rig.  Unfortunately there is still a good bit of it on there and I've been systematically removing it and replacing with Geocel Pro Flex RV.  It's a work in progress.

Dried silicone doesn't dissolve in anything well and so I find that abrasives are one way to remove the last bit of silicone after using a razor/knife.  Most often I start with a simple dry cloth to try and rub it off.  If I can get the bead to come loose intact it sometimes comes off as a whole piece/bead.  If it still has a decent bond then I try to soften with solvent and then continue scraping with a sharp plastic blade (doesn't cause as much damage as a razor blade).  Mineral spirits or turpentine have worked best for me.  No solvent will dissolve the silicone but rather they will often swell and soften and this can weaken the bond to the substrate and make it easier to scrape off.  It takes a little time to get the solvent into the silicone though.  I use a rag wet with solvent with a nitrile gloved hand to do this.

Once the silicone is off I've been using the Geocel Pro Flex RV instead and it's holding up really well.  This is not a silicone based product, but it's still clear.  It is not a true polyurethane based sealant but rather it is some other type of polymer that cures as it dries.  It's pretty sturdy stuff with excellent surface adhesion and doesn't come off like silicone.  But now I've got the same problem as the silicone:  how do I remove the Geocel Pro Flex RV when it comes time to do some maintenance?  I am not sure how many years I'll get out of the Geocel but eventually it's going to need to be replaced.  It doesn't come off easily at all and it's rubbery/flexible - all of this is good in terms of in-use performance, it just makes it hard to get it off when that becomes necessary.  Uncured material can be cleaned up with  "solvents such as MEK (lacquer thinner), Xylol, Toluol, or chlorinated solvents. Cured materials may be removed by cutting with sharp tools."  One has to be careful with those solvents because they will mess up the plexi windows in front or other plastic parts like tail lights. Like silicone swell with light petroleum distillates,  the Pro Flex RV can swell with a suitable solvent - but here we need an organic solvent and not a hydrocarbon like I use for silicone.  Fiberglass and rubber are OK with MEK or acetone or even some chlorinated solvents, but plastics are easily damaged or hazed.  Chlorinated solvents are not generally available at the hardware store so one might try MEK or acetone which you can find at the local hardware/big box store.  MEK has a lower boiling point so it doesn't evaporate as quick.  Acetone will be gone in an instant in hot weather.  Ideally I avoid using the solvents and am able to get it off with scraping, I only go to the solvent method as a last resort.

FYI, I compiled a list of non-silicone sealant materials that are relevant to RV use:

Dicor Lap Sealant 501LSW is self-leveling and designed for fiberglass roofs. 
Dicor Butyl Seal Tape, BT-1834-1, typically is used on roof vent flanges, furnace exhaust ports, etc.
Dicor Lap Sealant 551LSW is non-self-leveling with low sag properties. It is designed for vertical surfaces
Sikaflex-252 is an elastic bonding adhesive. It bonds and seals, has excellent gap-filling properties
Sikaflex-221 is a high-performance, no-sag polyurethane sealant that cures on exposure to atmospheric moisture
Sikaflex 219-LM is a low-modulus elastomeric polyurethane sealant, similar to Sikaflex-221 except that it has excellent flexibility
Geocel Pro Flex RV Flexible Sealant is a nonsilicone product specifically designed for RV applications such as windows and body trim.
3M 06580 Marine Adhesive/Sealant Fast Cure 4000 UV
3M Marine Adhesive Sealant Fast Cure 4200
 

[WME]

Pro level silicone remover...https://prosoco.com/product/dicone-nc9/

Stuff around the house that helps a bunch...WD-40, vinegar .

[Iflyfish]

Good stuff. Thanks

[AtlantaCamper]

I'm going to post a follow up here about silicone removal and choice of sealant and application techniques.  It may be useful to someone in the future doing a search in our forums.  

After looking at the image Iflyfish posted and commenting on alternative sealants instead of silicone, I ended up going out and taking a close look at my own sealing on the front wrap around plexi windows in my Sunrader.  OMG, a LEAK!  I have been doing a hack job of sealing and re-sealing the front plexi window gaskets for several years (initially with silicone...) and it has finally caught up with me.  There were two issues, the marker lights above the window were giving out and need replacement and there were a few small leaks in the front windows.  The leak was small and caused no damage, but I decided to try and take care of it properly this time.  

Here is a summary of the approach/method:

1. remove all sealant around marker lights and front plexi window gaskets
2. remove old marker lights
3. use Zep wax stripper/tool to remove all polish/sealant/silicone
4. remove all remaining sealant from rubber window gasket
5. Use Bar Keepers Friend to clean gel coat
6. attach new marker lights using butyl tape only
7. seal window gasket wtih ProFlex RV clear sealant
8. re-apply zep wax after sealant has dried

Supplies/materials/tools (i'm excluding all marker light install stuff like soldering here, just focusing on sealing):

• Zep floor wax stripper (contains a mixture of strong organic solvents)
• Tool for removing old sealant (painters tool)
• ProFlex RV non-silicone solvent based polymer sealant
• Butyl tape
• towels (paper/cloth), nitrile disposable gloves
• liquid soap solution (for smoothing sealant bead)
• caulking gun
• Small pieces of 120 grit sandpaper 
• Several new course green scouring pads
• BKF (bar keeper's friend)

I'll give a few hints and observations about the process for those looking to seal up their own front plexi wrap around windows.  First, the tool I found to be most efficient to remove old sealant and not leave scratches in the fiberglass gel coat was a regular painter's tool like this:

BUT, I modified it by sharpening it on a belt sander so all edges were very sharp.  This would gouge and damage the gelcoat so I then carefully sanded the sharp edge down to round it off just a bit so that it was not razor like sharp (razor blades are a no-no on gelcoat -- too sharp, cause damage) but it could still easily remove any sealant that was present.  I was able to use a lot of pressure this way but not cause any damage to the gelcoat.  It make it easy to get even the most stubborn silicone or adhesives off but didn't damage the fiberglass surface.  

One thing I decided to do was to take all of the previous layers of gunk off and get down to the clean bare gelcoat/rubber substrate surfaces.  Applying sealant on top of old sealant or on to of the zep wax has not worked well in the past.  What I found was that in the process of removing the zep wax with the stripper, the stripper also acted as a very good solvent for removing the various sealants/silicone that was there before. A win-win.  Scraping the swollen sealants with the modified painter's tool after applying the zep stripper was a good process.  BEWARE that the zep stripper solvents can easily etch the plexi window so you need to be very careful to quickly clean up any stripper that gets on the plastic windows. 

Once the wax was gone, cleaning the last remaining stuff on the surface was easily accomplished with good ol Bar Keeper's Friend and some nice new green scouring pads.  At this point the only old sealant left was on the rubber window gaskets.  I could tell from previous attempts to seal this rubber that failures had happened at points where there was 'sealant over sealant'.  I found that using small squares of sandpaper carefully used along the rubber would get me down to the bare rubber and remove anything else. 

I attached the marker lights with just the butyl tape and screws.  I left water drains open in case water gets inside the light (it will) but there isn't any path past the butyl tape for water to get into the interior.  i don't think any other sealant will be needed on the marker lights and it makes a nice clean install with just the layer of buyl tape.  I'll see how that works in a year or so i guess.

Application of the ProFlex RV was easy once I figured out the special soapy finger tooling method.  With a rubber/nitrile gloved hand you dip a finger in a soapy water solution and this makes it SO much easier to smooth/tool the ProFlex bead into a nice clean application. Doing only about a foot or two length at a time, I applied a very small/thin bead and smoothed it over with this method and the result is much better than anything I've done previously with sealant.  A thin bead on window to rubber and rubber to fiberglass took about a third of a tube of proflex.  It dried pretty clear and the bond is very strong.  I think it's going to last a while.   

I put  ~5 coats of the Zep wax back on and it blends seamlessly with the old stuff.  It's pretty easy to strip off a section, do a repair or whatever, and then put zep back on and blend it with the existing wax layer.  It took a lot of steps, but since my previous efforts have all had failure points I think it was worth it to take the time and get everything down to the bare substrate this time and then use a 'proper' (non-silicone) sealant.

[linda s]

Well there shouldn't be any sealant on the rubber window gasket. If it leaks replace that gasket. Mine still doesn't leak after 33 years

Linda S

[Iflyfish]

Thanks AtlantaCamper. Great summary of your experience. Eventually it seems we all have to deal with this issue. 

Iflyfishconmitoyamigos

[AtlantaCamper]

2 hours ago, linda s said:

there shouldn't be any sealant on the rubber window gasket. If it leaks replace that gasket

Your point is well taken.  In my case the plexi window and fiberglass cutout have, um, issues and there is some warping that I doubt will ever be corrected without some serious fiberglass re-working and/or new windows.  So I do the sealant route.  Likely others could find themselves in a similar situation and this approach could apply to them.  Folks should  take Linda's advise and get a new seal before going the sealant route if they can.

[linda s]

I do know some people whose Sunraders had window cutouts larger than they should have been. In that case sealants are about all you can do unless you want to cut and shape a window by yourself. Not for the novice but some have done it

Linda S

[AtlantaCamper]

44 minutes ago, linda s said:

some people whose Sunraders had window cutouts larger than they should have been

that is definitely the case with mine. I've got a few small (<1/8") gaps between seal and fiberglass plus about 1/4" of  walking/warping of the fiberglass surface at the cutout (not flat/straight). Plus the corner bend on the plexi window is at least 3/8" off from the face of the fiberglass. In addition there is an area of fiberglass that seems to have been done poorly right in the original casing process. It is what it is, but all of this results in leaks. I've used this sealing approach ever since I got the rig and it always leaks within a year or two.  But this is the first time I've really done the whole sealing process carefully from start to finish.  I think this will last me quite a while.

Most of my fiberglass looks great but there are three small sections (front window, and two on rear driver's corner) where the actual fiberglass was made poorly.  Ripples and bumps and the gelcoat is thinner.  It doesn't hold the wax like the other areas.   It's not a repair, I can see from the inside of the fiberglass that it looks different.  I'm thinking that I have a "student model" because of these fiberglass issues plus you may recall that I've noted that the welding in the rear looks like it is "C" grade work from a high school shop class.  I'm not complaining , just observing.  I'll take my "student model" over no Sunrader any day.

[linda s]

Man they must have had a bad week at Sunrader when yours was made. My rear extensions are rock solid and same size as the Toyota frame. My son the car guy was impressed with how well it was made

Linda S