我发现玻璃胶干了，但它是否释放出甲醛仍然存在疑问。玻璃胶在固化过程中会排放刺激性气体，而干透之后，它依然会释放甲醛，因为这些有害物质并不会因为其干燥而完全消失。这意味着，尽管时间长短不一，玻璃胶可能需要很长一段时间才能完全释放所有的甲醛。

不同类型的玻璃胶有不同的表面干燥和完全干透的时间。一般来说，中性型玻璃胶通常需要2小时左右就能表面干燥，而酸性型则只需30分钟左右即可凝固。不过，无论是哪种类型，其完整乾透往往需要更长一些的时间，比如中性型需要48小时，而酸性型则大约24小时。

如果你想对某个地方进行修补，那么必须在表面凝固之前完成操作。在使用分色纸覆盖特定区域时，一旦涂上玻璃胶，就必须在外皮形成前移除，以避免延迟固化过程。

glass adhesive drying process is from the outside in, and different types of adhesives have different drying and curing times. Therefore, if you need to repair a surface, you must do so before the adhesive dries (acid-base glue and neutral transparent glue usually take 5-10 minutes, while neutral colored glue takes 30 minutes). If you use a separator paper to cover a certain area, apply the adhesive first and make sure to remove it before the outer layer forms.

The curing time of glass adhesive also depends on the thickness of application. For example, an acid-based glass adhesive with a thickness of 12mm may take 3-4 days to fully cure, but within 24 hours, its outer layer will already be hardened. A room temperature-cured glass adhesive can reach an adhesion strength of up to 20 pounds per inch after just three days.

If the area where glass adhesive is used becomes partially or completely sealed off during curing time, this will affect how long it takes for it to fully harden - in fact under complete seal conditions it could remain soft forever! Increasing temperature can soften the hardening process too. The gap between two metal surfaces should not exceed 25mm when using these adhesives. It's important to thoroughly check for proper bonding after applying them even when they are sealed off until ready for use again.

Acid-based glues produce an acidic smell during their curing process due to evaporating vinegar content which disappears once cured leaving no odour at all later on.

When bonding materials like metals or plastics together:

Clean both surfaces thoroughly removing grease etc.

Use acetone (with appropriate safety precautions)to clean non-plastic surfaces

Sand rubber surfaces with sandpaper then wipe down with acetone

Apply glue evenly over prepared surface(s), pressing out any air bubbles as needed before allowing parts join together firmly