Yes, silicone can be used outdoors in sub-zero temperatures. Silicone is known for its ability to withstand a wide range of temperatures, including extreme cold. It remains flexible and retains its properties even in sub-zero conditions, making it suitable for outdoor applications in cold climates. However, it's important to note that the specific type and formulation of silicone should be chosen based on the intended use and the expected temperature range. **

Rocks do not actually have a smell themselves. However, sometimes rocks can emit a smell when they are heated or crushed. This smell is often due to the release of volatile compounds or minerals within the rock. For example, when rocks containing sulfur compounds are crushed, they can release a distinct rotten egg smell. **

Painted rocks are rocks that have been decorated with various designs, patterns, and images using paint or markers. People often paint rocks as a form of creative expression and then place them in public spaces for others to find and enjoy. This activity has become popular as a way to spread positivity and brighten someone's day when they come across a beautifully painted rock. Some people also use painted rocks as a form of outdoor art or to create a sense of community connection. **

Rocks are formed through a process called the rock cycle, which involves the transformation of one type of rock into another over time. The rock cycle begins with the cooling and solidification of magma or lava, which forms igneous rocks. These rocks can then be broken down into smaller pieces through weathering and erosion, and the resulting sediments can be compacted and cemented together to form sedimentary rocks. Over time, these rocks can be subjected to heat and pressure, causing them to undergo changes and become metamorphic rocks. This continuous process of formation, transformation, and reformation is what shapes the Earth's crust and creates the variety of rocks we see today. **

Yes, silicone does stick to silicone. When two silicone surfaces come into contact, they tend to adhere to each other due to their similar chemical composition. This property makes silicone a popular material for creating airtight seals and bonding silicone-based products together. **

Yes, climbing shoes suitable for indoor use can also be used outdoors on rocks. However, it's important to note that indoor climbing shoes are typically designed with a softer rubber compound that may wear out more quickly on rough outdoor surfaces. Additionally, outdoor climbing shoes often have more durable rubber and a more aggressive tread pattern to provide better grip on natural rock surfaces. Ultimately, while indoor climbing shoes can be used outdoors, they may not offer the same level of performance and durability as shoes specifically designed for outdoor climbing. **

For PVC and wood, a neutral-cure silicone is suitable. This type of silicone does not release any corrosive by-products and is therefore safe to use with PVC and wood. It also has good adhesion and flexibility, making it a suitable choice for sealing and bonding applications involving these materials. Additionally, it is resistant to weathering and UV exposure, making it a durable option for outdoor use. **

It is generally not recommended to apply new silicone on top of existing silicone. The new silicone may not adhere properly to the old silicone, leading to potential issues with adhesion and durability. It is best to remove the old silicone completely before applying a new layer to ensure a proper bond and a long-lasting seal. **