As a driveway paving contractor in Washington you will undoubtedly be used to using asphalt seal-coating. But sometimes, problems can occur.

If you are losing the pressure with your asphalt seal-coating system there could be more than one explanation as to why. We talk you through some of the reasons it might be;

HAS THE SEALER BEEN OVER DILUTED OR PERHAPS IS TOO THICK? and asphalt companies in Washington using asphalt sealer will know that the sealer comes in a concentrated form when it is sold and has to be mixed prior to use.

The sealer has to be mixed with a 10-15% dilution rate. In other words, this is ten or fifteen gallons of water for each hundred gallons of sealer concentrate.

When it is at the correct consistency, it ought to travel through your pump adequately. If it is not quite right – i.e. it has been diluted too much – you could end up with air bubbles in your pump. This is a prime source of losing pressure at the nozzle.

If this is the case, then you will need to add the concentrate back in until you have reached the target dilution rate.


Although there will be manufacturer’s instructions on the packaging, it is generally advised that the water is added to the tank before the concentrated sealer goes in it. Then it needs to be adequately diluted and mixed until it is at the right level.

However, it depends how you are placing the sealer onto the asphalt. If you are doing this manually, then it is not necessary to dilute it first.


If you agitate the sealer for longer than thirty seconds you could end up with it bubbling on you, which is going to cause problems for you in the pump. Try and remember not to overdo the mixing process.


One simple explanation as to why you may be suffering a loss of pressure in the pump, could be that there just isn’t enough sealer in the tank to begin with.

We would advise that there is never any less than thirty gallons in your tank at any given time. This is important as it ensures that the tank will not suck in air and give your pump difficulties. If it should dip as low as twenty gallons, you are going to lose pressure.


One reason that your system is not performing up to standard could be because it is blocked. The blockage may be in the suction pipe, which is at the end of the tank.

It could be that there is some sediment down there and it is causing a blockage in the suction port.

You can buy kits to manually mix the tank before you switch on the unit. You may also use a paddle to reach through the tank’s lid and get the sealer moving about at the rear end of the tank, where the problem is occurring.


Are you using a trigger spray gun? This may have become blocked up and be in need of a clean.

Ideally, we would recommend that you flush out your spray gun every day to prevent blockages. Just running some water through it might be enough maintenance if it is done regularly enough.


If you have tried all these troubleshooting suggestions and none of them have worked, then you may need a plan B.

We would suggest always taking a sealer brush or maybe a squeegee with you, just in case.

Then all you have to do is pop the hose off the spray gun and get the sealer out to the section you are working with. It can then be spread manually if you have to.