There are a variety of different Drywall Compounds available for installing and repairing drywall but the selection comes down to three basic types. Each one has its own use and although you can mix them up a bit best results will happen if you stick to their intended use.
The first type is self curing compound which uses a chemical process to cure. This is also called fast setting compound because it has a rated time that it is usable. Most of the self curing compounds give you between 5 and 30 minutes of working time and when the time is up you should have all the product on the wall and your tools should be roughly cleaned. Self Curing or Quick Set Drywall Compound is really great for cold or humid working conditions where you need the product to harden but you can’t rely on normal air drying compound. Although Quick Set compound will cure in cold conditions you still have to work within a temperature range that will allow it to cure so read the directions on your box before you mix it up and if you need to add space heating then do it. This product comes in a powder form and needs to be mixed in small batches with water to begin the curing process.
Quick Set Compound is also required if you are using Mesh Tape because without it the tape can fail and crack. Another primary use is to fill all of the gaps between the sheet rock before you apply your tape because that will allow you to continue working where an air dry compound would have you waiting for it to cure before you could apply tape.
General Purpose Drywall Compound is probably the most common selection for professionals and do it yourself projects. Like its name General Purpose Compound can be used for all purposes of installing or repairing drywall. It can be used with fiberglass mesh or paper tape and it is the best product to use in equipment like a bazooka or bandjo tape machine. General Purpose Compound comes either in powder form or it can come premixed. Premixed compound will need to be mixed before application but has the water needed to allow it to apply evenly. You should not use this product with mesh tape or it could result in cracking.
Lightweight Drywall Compound is the final type of compound that you might use when fixing or installing drywall. Its primary purpose is the final coat of compound just before sanding because it applies to the wall very smoothly and it sands well and quickly. Spackle is also a lightweight type of drywall compound but it is sold in much smaller 1 gallon to Pint sized containers and is normally used when you want to do finishing repairs to fix popped nails or fix other damage but you don’t expect to repaint an entire room. Lightweight Compound is air dried meaning it takes time to dry before you can sand or work with it.
Self Curing Vs Air Dry Drywall Compounds
As we have seen above there is only one type of compound that is self curing and that is one that is labeled as a Quick or Fast Setting Compound. All of the other products require higher heat and longer times to cure. You should never try to force drywall compound to set quicker by using a hair dryer or heat gun or forced air but when necessary you will have to turn up the furnace or add space heaters to homes that are under construction. If you don’t have enough heat for general purpose or lightweight compound to cure then it will take many days and there could be problems with adhesion and cracking. Follow directions as the manufacture lists.
When picking a self curing drywall compound understand that in very cold or high humidity conditions there could be extended wait times of even days.
Final Note
When picking drywall compound it is best for small jobs to stick with general purpose compound. Although it takes longer to cure it has all the properties needed to complete any type of job whether its adding drywall to your garage walls or repairing a hole in the wall.
If you are remodeling a large room or hanging drywall in an entire house there are other considerations such as time. Normally you want to hang and tape your walls in the same day if you can so self curing or fast setting drywall compound will allow you to fill the gaps between sheets and then come back with a general purpose compound to lay down your tape in the same day.
Lightweight Compound is for finishing and after you have applied your tape and first coat of mud you can complete the job with lightweight compound to provide a smooth finish that is easy to sand.
Mesh Tape should not be used today. Although it is available and will be you won’t see most professionals using it because of its higher failure rates. The reason it was designed was because home owners applying paper tape wouldn’t have enough mud under the paper tape and then it would lift or bubble. It is better to learn the skill of properly applying paper tape then to try to use mesh tape for installs or repairs.