1. Water, any area that holds water sealer may not bond well. Example- low spots in your asphalt or around flower beds.
2. Excess watering from sprinkler systems.
3. Trees, Trees may affect your sealer in two ways one is because of the shade they provided may not allow enough sun in to allow good bonding of sealer. Two if your trees shed sap then the sealer is sticking to sap instead of asphalt and when sap lets go so does sealer.
4. Excess Salting and certain kinds of salt can affect sealer.
5. Snow Plows- Snow plowing should always be done with skid shoes and a 1/16 to 1/8 of an inch of snow should be left on black top to melt off. If the snow plow uses to much force it will scrap off sealer and also pull out crack filler. Snow plows also should never use chains.
6. The kind of sealer used on your blacktop prior, if it is cracking and pealing up in areas when you put new sealer over it as the old continues to let loose it will take the new sealer with it.
7. Oil spots and grease.
8. Of course quality and condition and age of asphalt before sealing, example if you have a rough surface with rock sticking up you will get a polish rock look.
9. It is normal to see wear in drive lanes if you have a lot of traffic your asphalt is still protected if you look close.
10. Primer can help some of these situations but it’s an additional cost and still don’t always work 100%