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Before bonding with the molten glue, you must prepare yourself and your surfaces. Firstly make sure you are using protective eye wear and heat resistant gloves, as well as full length sleeves. The aim is to minimise the possibility that molten glue come into contact with exposed skin, hair or eyes. Next, prepare your surface being bonded. It is imperative that the surface is free of contaminants, like dust or water. In some cases it is worthwhile to lightly abrade the surface so that the bond may be improved and with surfaces like metal you will get a better bond if it is pre-warmed up to 95°C. When bonding the surfaces, it is best to apply the glue to the more difficult to bond surface, (generally hard smooth surfaces are more difficult to bond than the more porous surface). Next, after the glue has been applied, mate the two surfaces together as quickly as possible and apply as much pressure as practically possible, making sure the surfaces are not moved or adjusted after contact has been made. This will ensure the best possible bond. As long as it has been bonded correctly then typically you will have achieved approx 50% of your strength after 1 minute, 75% after an hour, and full strength after a full day. For some final tips; “open time” of the hot melt glue will vary depending on a range of factors such as; application temperature; amount of molten glue applied; type of substrate and ambient temperature conditions, and operator application technique. As some glue formulas result in more flexibility or “rubberiness” this can result in difficulty in running them through some hot melt glue guns, especially after idle durations greater than 20 minutes. It is recommended to run these types of products in guns have flexible feeding (inlet) tubes or semi-rigid Teflon feeding tubes – and also to keep idle times down to a minimum.
