Silicone application tips

[Namrups]

I have worked for a major silicone manufacturer for 34 years. Here are some tips for using silicone in this application.

The main purpose for silicone is to seal between the aluminum panel and the supporting framework. Does silicone have good adhesion properties? Yes it does. If you try to remove a properly applied panel you will damage it. But the rivets are the main force holding the panel in place.

Basic's

I'm sure most of you know this but I am going to go over it for those that don't.

The Caulking Gun

There are a number of different manufactures of hand operated caulking guns on the market that can vary widely in price. They all have the same parts and work the same way.
https://thefactoryfiveforum.com/attachment.php?attachmentid=160109&d=1642084494

Plunger Bar

The plunger bar pushes against the plunger in the caulker to force the silicone out of the caulker.
https://thefactoryfiveforum.com/attachment.php?attachmentid=160114&d=1642084532

Plunger Bar Locking Cam

The plunger bar locking cam is spring loaded and locks against the plunger bar so that when you squeeze
the trigger is forces the plunger in. The only way to move the plunger bar in or out by hand is to press on the plunger bar locking bar cam with your thumb. By holding the cam in it will release the plunger bar and you can move it in or out to install or remove a tube of caulking.
https://thefactoryfiveforum.com/attachment.php?attachmentid=160116&d=1642084532
https://thefactoryfiveforum.com/attachment.php?attachmentid=160115&d=1642084532

Trigger

Squeezing the trigger will force the plunger bar against the plunger in the tube and out the nozzle.
https://thefactoryfiveforum.com/attachment.php?attachmentid=160122&d=1642084570

[J R Jones]

Namrups, You do not mention the wet finger for pushing and forming wet silicone into place.
Actually I resorted (invented?) another technique recently with Pliogrip panel bonder for the depth of a tight joint. I laid down the bead as close as I could get it, then used an air gun blast to blow it to the deepest part of the joint.

I have a concern about the panel bonding you address here. The bead will be random and potentially it will not compress to fill the entire surface interface. That provides a tight void that can become wet and hard to dry. The crevice is subject to corrosion due to dissimilar metals and the wetness. I understand that some silicone compounds can be corrosive, as in electrical circuits. Bare aluminum?
jim

[Namrups]

The Caulking Tube

There is an aluminum foil seal just below the nozzle to keep the silicone from curing in the tube. You can see the square piece of foil in the picture below. The seal needs to be punctured before putting pressure on the plunger bar. If you don't puncture the seal and pressure the plunger bar, the pressure will get to the point that the seal will BURST and then you will have a mess. (believe me)
https://thefactoryfiveforum.com/attachment.php?attachmentid=160111&d=1642084494

Cut approximately 1/4 inch off the end of the nozzle.
https://thefactoryfiveforum.com/attachment.php?attachmentid=160124&d=1642086442

Any stiff object that is long enough to reach the seal can be used to puncture it. Some caulking guns actually have a bar attached to them that can be used. In the picture I have a wooden Q-tip and a piece of heavy gauge wire. A long finishing nail would also work. Anything that is stuff and will fit onto the hole.
https://thefactoryfiveforum.com/attachment.php?attachmentid=160118&d=1642084532
https://thefactoryfiveforum.com/attachment.php?attachmentid=160117&d=1642084532

[Namrups]

Bead Application

Once you have punctured the seal you can use the tube. You want to apply an even bead. I will admit that this takes practice but think of it like learning how to use the gas pedal and clutch. We all mastered that.

The speed that you move the caulking gun and the amount of pressure you put on the trigger will dictate what you get for a bead.

Squeeze to hard and/or move to slow and you will apply to much material.
https://thefactoryfiveforum.com/attachment.php?attachmentid=160121&d=1642084570

Squeeze to little and/or move to fast and you will not apply enough.
https://thefactoryfiveforum.com/attachment.php?attachmentid=160120&d=1642084570

Work to get the right speed and right pressure on the trigger to lay a good bead. It takes practice.
https://thefactoryfiveforum.com/attachment.php?attachmentid=160113&d=1642084494

IMPORTANT!! AS YOU ARE NEARING THE END OF THE BEAD YOU ARE PUTTING DOWN PRESS ON THE PLUNGER LOCKING CAM WITH YOUR THUMB. THIS WILL RELEASE THE CAM AND RELEASE THE PRESSURE ON THE PLUNGER. IF YOU FAIL TO DO THEI THE MATERIAL WILL CONTINUE TO OOZE FROM THE NOZZLE UNTIL THAT PRESSURE IS GONE.

If you cut the end of the nozzle to big you will get way to much material being extruded even with a light touch.
https://thefactoryfiveforum.com/attachment.php?attachmentid=160112&d=1642084494

When your done for the day let a small amount of caulking extrude from the end of the nozzle. It will cure and then the next time you go to use it just pull the cured material off and your good to go.
https://thefactoryfiveforum.com/attachment.php?attachmentid=160110&d=1642084494

[Namrups]

Cleanup

It is almost impossible not to get some ooze out at some point. This needs to be wiped up before it cures. Acetone, Toluene and IPA (rubbing alcohol) can be used if the material is uncured.

[Namrups]

Namrups, You do not mention the wet finger for pushing and forming wet silicone into place.
Actually I resorted (invented?) another technique recently with Pliogrip panel bonder for the depth of a tight joint. I laid down the bead as close as I could get it, then used an air gun blast to blow it to the deepest part of the joint.

I have a concern about the panel bonding you address here. The bead will be random and potentially it will not compress to fill the entire surface interface. That provides a tight void that can become wet and hard to dry. The crevice is subject to corrosion due to dissimilar metals and the wetness. I understand that some silicone compounds can be corrosive, as in electrical circuits. Bare aluminum?
jim

Yes Jim, you can use a wet finger to "form" a type of joint. (A soapy wet finger would work even better.) I would not be worried about filling the entire surface area of the joint you are working on. Think of silicone as a gasket/O-ring. It does not have to fill the full surface area to seal. The bead in the pics is approx. 1/16" wide and is more than enough to seal between the panel and the frame it's being attached to. It does not have to cover the entire width if the frame to be effective.

Certain types of silicone are very corrosive. If you get a very strong vinegar order (it will clear your sinus's) don't use it. That material gives off acetic acid as it cures and will corrode more than just the aluminum. Normal window and door caulking as is shown in the pictures will not corrode the aluminum or damage most finishes applied.

Use caution when trying to use silicone as a joint filler. In order for the silicone to cure it needs moisture from the air to chemically cure. If the joint you are trying to fill is too deep the material may never cure because moisture can not penetrate deep enough.

[dukegrad98]

You know what irks me? I think in every one of the last three or four projects I have done involving caulk, using the basic $5 caulk gun shown above, I've had the back end of the tube blow out on me at some point during the work. Then I wind up with a huge mess on my caulk gun plunger and a lot of wasted caulk. I figure it's just another result of expecting everything to be manufactured as cheaply as possible. I usually grab GE caulk products at the local big box store, but I'll also be the first to admit that GE isn't the company it used to be.

Cheers, John

[Namrups]

You know what irks me? I think in every one of the last three or four projects I have done involving caulk, using the basic $5 caulk gun shown above, I've had the back end of the tube blow out on me at some point during the work. Then I wind up with a huge mess on my caulk gun plunger and a lot of wasted caulk. I figure it's just another result of expecting everything to be manufactured as cheaply as possible. I usually grab GE caulk products at the local big box store, but I'll also be the first to admit that GE isn't the company it used to be.

Cheers, John

When you blow past the plunger and make the mess it means there was cured material in the tube that is holding the plunger up until the pressure overcomes the plunger seal. You should not have to put a lot of pressure on the trigger to extrude material. If it is hard to squeeze stop and check your nozzle for blockage.
These plastic tubes do not keep moisture out forever. Typical shelf life of a tube is 1 - 2 years. Each tube has a "use to" date but in most cases its not clear how to un-code it. Big box stores usually turn their inventory fast enough that most of the time these tubes are good. Smaller outlets may not move the tubes as fast and may have old product on their shelves. Knowing the code of the GE material I have seen product that was 4 years old on my local hardware stores shelf. If you squeeze the tube it should give slightly. If it feels solid, put it back.

[J R Jones]

Namrups, I would be delighted if I pulled the cured "dangle" out of the nozzle and went on with a subsequent application, but it does not work that way for me.
Some screw caps stop cure in the nozzle, but not always.

When my efforts are stymied by nozzle cure I feel soft unused silicone in the container. With the alternative of driving to a remote retailer for a replacement I endeavor to pick-out the plugged material with a mini screwdriver or a scratch awl. Failing that I hold the tube aperture to a 1/4 inch drill bit in the drill press, squeezing to expel cured material. The drill results in a gusher, like an oil well, and a gooey drill bit. Inevitably cured silicone chips are in the tube and populate the seal bead like boogers. Polyurethane adhesive has a similar malady.
Manufacturers investing in sealing caps would save frustration; and sell less silicone. Ahh, there it is.
jim

[mikeinatlanta]

It's worth noting that one should only use silicone that does not contain acetic acid. Many silicones have it and the acid will etch the aluminum so either check the MSDS or the manufacturer. Will also not have a strong long term bond. Never use silicone in any area that may be painted. Best is to use a proper automotive sealant where trying to seal and a urethane adhesive where looking for strength (not epoxy).