In nearly any project you’ll be working with some sort of metal. From appliances to door frames, it’s important to be prepared with the best sealant for metal surfaces. Here’s what you need to know to choose the best sealant for any projects ahead of you.

What Type of Metal Are You Sealing?

Silicone metal sealant comes in two basic formulations: acid cure and neutral cure. Acid-cure silicone releases acetic acid (also known as acetoxy-cure silicone). Acetic acid is corrosive to copper and brass and has a strong vinegar smell while curing. Neutral cure silicone, on the other hand, has an alcohol and oxime curing process that is not corrosive to metal. It releases a gentler odor while curing than acetoxy-cure silicone.

Both types of silicone will create an excellent bond to metal, but because neutral cure silicone isn’t corrosive, it’s usually a better choice for projects that involve sealing metal surfaces.

What Conditions Will the Metal Sealant Face?

In addition to the chemical properties of the metal and sealant, you'll also want to consider the conditions these seals will need to hold up to. That will change which silicone sealant formulation will work best for each project.

Temperature

Metal is strong and can withstand extreme conditions, so it's often the material of choice when making something that will face extreme temperatures. The metal sealant you use needs to match the metal work in tolerating extreme temperatures without the seals melting, burning, or breaking.

RTV silicone sealant will stay tight without peeling away through the cold from the metal and still be flexible when things thaw. Metal expands as it heats and shrinks as it cools and the stretchiness of silicone ensures the seals will hold and flex right along with it. For situations that involve extremely high heat, like the seals in car engines, commercial kitchen ovens, or rooftop HVAC units, high-temp sealant is usually the best choice and can withstand over 500° Fahrenheit.

Water

Another concern for metal-work is waterproofing. Water will rust some metals away or can cause problems with electrical components in addition to the usual risks of dampness inviting mold and mildew. Neutral cure silicone sealant is a great solution for waterproofing, both for the initial installation and any repairs that may come along.

Tips for Creating A Seal that Lasts

When it comes to sealing metal surfaces of any kind, preparation is absolutely the key to success. Here’s how to prepare metal surfaces perfectly to ensure a seal that will last.

Step 1: Get Down to the Metal

In any situation where you're cleaning away old sealants or built up grit, you may need a hammer and chisel, an electric metal brush, or sandpaper depending on the project. It’s important to fully remove anything on the surface of the metal before you try adding new sealant.

Step 2: Clean the Surface

Now that the metal is exposed and smoothed off, it needs to be cleaned of any oils or fine grit that would prevent the silicone from fully bonding. Denatured alcohol is usually the best thing for stripping oils away from metal surfaces, and if you're cleaning away residual gasoline or silicone, it'll do the job! If you’re in a pinch, some dish soap and hot water can go a long way.

Step 3: Dry Everything Completely

Silicone will not stick to wet or damp surfaces. Everything must be bone-dry for it to adhere completely. A hair dryer or a fan can help speed up the drying process, but it’s better to take your time on this step than rush and end up with a faulty seal.

Buy the Best Sealant for Metal Surfaces

The last, and most important tip, is to buy the best silicone metal sealant you can find. At Silicone Depot, we offer top-shelf sealants at excellent prices. We'd be happy to help you choose exactly which silicone metal sealant you need and make sure it gets to you in time for your next project. Call us today at 812-824-8000.