How We Select Glues
ToxicityAs much as we all love glue, we need to treat it with respect, because many glues can hurt us. It is the manufacturers responsibility to tell us if their glue is toxic, it is our responsibility to read the label.
There are three ways a toxic substance can enter your body:
- Inhalation (breathing)
Always use smelly glues in a well ventilated area. Using glues outside is better than inside, only if there is a steady directional breeze. It is better to create your own draft in a controlled environment. Your oven hood can be a controlled draft. Or you can set a fan towards an open window. The most important thing to remember is to keep yourself out of the contaminated cross draft.
- Ingestion (eating)
Be sure to wash your hands after using any glue.
- Absorption (through the skin)
Glues that contain solvents can be absorbed through the skin. Latex gloves are breathable, and don't keep the bad stuff out. Rubber dish gloves are what we recommend. But don't wash your dishes with the same gloves you used to fix your lawn furniture.
Please take care.
|Inhalation:||Don't spend all day with the stuff under your nose.|
|Inhalation:||Use with ventilation and for short periods of time.|
|Inhalation:||Do what ever possible not to breath this stuff at all.|
Use it inside a box or under the oven hood.
|Ingestion:||Don't use this on your cereal in the morning.||Ingestion:||Wash hands before you eat or smoke.|
|Ingestion:||Do not let this stuff get any where near your mouth.|
|Absorption:||Don't bath in the stuff.|
|Absorption:||Wash your hands after using it.|
Time to AdhereSome glues adhere (dry) in 30 seconds, some in 24 hours. The manufacturer should tell you the set up time. However there are external factors that may effect this time. For example:
If it is cold your glue may take longer to work. This is particular to two part epoxies, and PVAs.
Your glue will set faster in the desert than in the rain forest. In other words, humidity slows down setting.
- Amount of glue in bond
PVAs and cyanocrylates take longer to work the more you use. Epoxies set up faster in larger amounts.
CostIt can be rather daunting at your local hardware store, standing in front of that wall of adhesive, attempting to chose the right one to stick this to that. Although we hope to help with this decision, you will still have to be the one to consider cost. Here are some points that will help you with this decision.
- Generally, spray adhesives don't go as far as liquid or paste adhesives, so if you don't need the smoothness that a spray adhesive provides, don't use it.
- Cyanoacrylate, although seem expensive considering the small amount that you get, a little goes a long way.
- Every glue goes farther if properly stored to prevent dehydration and evaporation.
StrengthAt this to that, we always try to recommend the strongest glue for the circumstances. Remember though, the strongest adhesive for this to that is only as strong as the weakest material in your union. We don't recommend a glue any stronger than your weakest material.
FlexibilityFlexibility is an important consideration when choosing the appropriate adhesive. If both of your materials are flexible, you should chose a flexible adhesive. If you are gluing a flexible material (fabric) to a non flexible material (wood) there is probably no point in using a flexible adhesive. In this case, we would recommend a rigid adhesive.
Gap Filling AbilityIt is an ideal union that fits perfectly. But as with most conditions in life, this isn't always the case. If what you want to glue together has small gaps you will need a glue that has enough viscosity to fill these gaps. One that we recommend is "Specialty Epoxy Putty" manufactured by Polymeric Systems, Inc. With some glues, you can add your own filler to create a gap filling glue. Here are some ways to increase gap filling ability.
- Talc or baby powder can be added to epoxies. This does slow down the cure time.
- saw dust can be added to P.V.A. glues, wood glues and white glues. Remember, these glues need air circulation to dry and adhere, so don't apply too thickly, or it will take for ever to dry.
TemperatureSome glues need room temperature or warmer to set up.
Epoxies will deteriorate an existing bond in sub zero (Celsius) temperatures.
PVAs will set in temperatures above zero (Celsius), as long there is good air circulation.
SandabilitySome glues sand well, and others don't. If you need to sand your materials after they have joined remember to following:
Glues that sand well:
- Krazy glue
- Super glue
- Rubber cement
- PL 200
VisibilityIf you want your repair job to be invisible, you will need to consider the visibility of the adhesive you are choosing. Here are some tips to help you with this consideration:
- Any glue that contains a solvent (indicated by words like petroleum distillate, acetone, toluene etc) will leave an oily stain on any porous material.
- PVAs (wood glue or white glue) acts as a sealer on porous materials, and will prevent treatments such as dye or stain from acting on the material. If you want to stain your material after gluing it, you need to clean up your join well. Luckily these glues are water based and clean with warm water if they haven't completely dried.