Organizing a yarn stash involves several strategies that cater to different preferences and spaces. First, consider grouping yarn by weight or color to make selection easier for projects. Utilize clear bins or baskets to separate these categories, allowing for easy visibility and access. Labeling bins can further streamline the process. For those with limited space, hanging shoe organizers or wall-mounted cubbies can be effective vertical storage solutions. Implement a system that suits your crafting habits, such as keeping current project yarns in a dedicated basket for easy reach. Regularly decluttering your stash, perhaps annually, by donating unused yarn can keep your collection manageable and useful.

Tungsten, with a Mohs hardness of about 7.5, is indeed harder than titanium, which has a lesser hardness of around 6 on the Mohs scale. This scale, used for comparing the scratch resistance of materials, ranges from 1 (talc) to 10 (diamond). Tungsten's superior hardness is attributable to its dense, tightly-packed crystal structure, making it highly resistant to scratching and wear, whereas titanium, though less hard, is renowned for its strength-to-weight ratio and corrosion resistance. This makes tungsten popular for applications requiring extreme durability, such as tooling and jewelry, while titanium is favored in aerospace, medical implants, and other areas where its lightweight and strength are essential.

Allergic reactions to polypropylene are considered extremely rare since it's a type of plastic widely used in daily life, known for being hypoallergenic. This material is found in various products, including medical devices, textiles, and packaging. An allergic reaction might not directly stem from the polypropylene itself but could be due to additives used in the product's manufacturing process or a reaction to something else in the environment mistaken for a polypropylene allergy. Symptoms of an allergic reaction could include itching, redness, or rash. If suspected, it's essential to consult with a healthcare professional for appropriate testing and diagnosis. They might recommend patch testing to identify the specific allergen. For individuals with a confirmed sensitivity, avoiding products containing polypropylene and seeking out alternatives might be necessary.