How to Remove Silicone Caulk/How to Reseal End Caps & Windows

Topic: How to Remove Silicone Caulk/How to Reseal End Caps & Windows (Read 1529 times) previous topic - next topic

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February 23, 2019, 03:40:21 pm

I am the second owner of a 2003 30'IB. The end caps need resealing. The prior owner had used silicone caulk on the rear end caps of the unit. From a posting by Larry W a few months ago, it appears that I have a problem. Is there no way to clean off the silicone in prep for the application of the 3M product that is recommended? I am not really interested in taking off the end caps and live in Wisconsin so a trip to the factory isn't practical. I suppose I could just eterna bond the end cap seams, but my wife would not like that option for aesthetic reasons. Any thoughts would be appreciated. PS I am sitting in Kerrville TX right now, so weather wise I can work on it.

Re: Removal of silicone caulk-end caps

Reply #1 – February 23, 2019, 04:09:18 pm

You might try this 'mystery silicone caulk' remover from McMaster Carr; I have no idea if it works, but you might call them and describe the surface - the end caps are ABS plastic, as far as I know - and ask for their suggestions.

McMaster-Carr

All traces of silicone have to be removed or the 5200 (or other 'appropriate' sealant) won't stick.

Others are pretty sure to offer suggestions!

Re: Removal of silicone caulk-end caps

Reply #2 – February 23, 2019, 04:10:42 pm

Bob, if there is ANY residual film from the silicone caulk, nothing is likely to stick. Eternabond might look ok on the outside but underneath, where a bond should be, there may be a thin space. Capillary action could draw water into that space.

So, how to get it off? Well, the non-volatiles in silicone caulk can penetrate any kind of porous surface. I think you might have to scrape off what you can, then use a strong solvent to wipe, then fine sandpaper to cut at least part way through the paint, if not all the way, then another solvent wipe. That MIGHT get enough off so you can start again, but no guarantees.

Ken F in NM

Re: Removal of silicone caulk-end caps

Reply #3 – February 23, 2019, 06:33:42 pm

If nothing will remove the silicone adequately, would using silicone again be an option? Does new silicone adhere to old silicone?

Re: Removal of silicone caulk-end caps

Reply #4 – February 23, 2019, 07:18:18 pm

"Does new silicone adhere to old silicone?"

Unfortunately, no. The stuff is a curse.

Re: Removal of silicone caulk-end caps

Reply #5 – February 24, 2019, 01:13:05 pm

The previous owner did you a disservice using silicone. The stuff only belongs on machined metal parts that are designed to come apart. You will need to totally strip the silicone contaminated surfaces to bare metal and plastic.
Are the caps intact or loose?

Here is what I would do. Using a sharp utility knife, undercut the sealant on the caps as far inward as possible. Cut away as much silicone as possible. Then use plastic razor blades to remove the rest of the surface silicone. The plastic blades will not damage the paint.
Amazon.com: 100 Single Edge Plastic Razor Blades: Cell Phones & Accessories

After this, use masking tape off the surrounding areas along the edge of the caps and wall, leaving a 1/8" gap. Apply two or three layers of tape for better protection of the paint.
Window and seam sealing | Flickr

Wedge open the loose caps to allow cleaning even deeper under the caps.
Plan on screwing the loose caps into position using #8 X 1" stainless steel sheet metal screws. Drill pilot holes using a very small drill bit and then open up the holes through the plastic caps, drilling them one drill size larger than the screw diameter, to help prevent cracking of the cap.
Where ever a cap will not lay flat and tight, use a screw, it's what the Mothership does when installing caps .

Use emery cloth to sand a narrow strip along the edge of the cap all the way to shiny metal, getting under the cap as far as possible. I also use dental tools, broken hack saw blades and even a Dremmel tool, with cutting disc and sanding drums, whatever it takes to clean out the loose adhesive tape and to open the metal up.

After the cleaning is done, wash the surfaces to be glued with a paint prep solvent.
Eastwood PRE Painting Prep
I would be temped to use an etching solution, such as phosphoric acid on the bare aluminum, before glueing, to remove any aluminum oxide that has built up.

When the prep is done, use 3M 5200 Fast Cure to seal and glue the caps back into place.
Wear old clothes and buy a box of disposable gloves, I wear two or three pairs or gloves at a time, throwing them away as they get soiled, polyurethane is sticky stuff that is hard to get off hands and clothing.
5 mil Nitrile Powder-Free Gloves 100 Pc X-Large
Wedge open the loose sections of cap, so the adhesive can be pushed up under the cap, I use ice cream sticks for this.

Applying a good bead of the 5200 to the gap and a use a gloved, wet finger to force the sealant up under the caps.
Install the screws and then smooth the bead. Do not over tighten the screws, use them to pull the cap into place so it sits flat. A wet finger is the best tool for sculpting the adhesive, the moisture will not adversely effect it.
As soon as a satisfactory bead is achieved, remove the masking tape, before the 5200 skims over.
Resist the urge to work the sealant once the tape has been removed, any cleanup should wait for a half hour or so.
Use a rag and lacquer thinner for cleanup.

This is going to be an involved job, do one cap at a time.
Have fun
Larry

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Re: How to Remove Silicon Caulk/How to Reseal End Caps & Windows

Reply #6 – February 24, 2019, 01:50:30 pm

Since the topic of caulk removal and resealing end caps and windows comes up frequently, I have pinned this thread, which includes Larry's precise resealing instructions - with links to photos.

Chris