The short answer is that in 99% of cases, yes, but you must check to be sure.
There are three types of sealer.
We would always recommend that you test a small area, and for this you will need a 2 inch paint brush, a small paint scraper, a flat screwdriver and a small plastic or metal bucket to pour the solvent into [you can order a small 1 litre can of solvent from our website].
Choose a small area to test, probably about 200mm x 200mm (8 inches x 8 inches) and in a low wear area, which will still have a good layer of the old sealer on it. In high wear areas, the original sealer may have worn off.
First of all, apply some solvent to the test area with a paintbrush, rub around and agitate briskly with the paintbrush for 5 minutes.
If the sealer has not softened repeat the process and if the sealer still does not soften it is a polyurethane. Unfortunately no sealer, not even another polyurethane, will adhere so you will need to strip it off before starting [please call us for advice on stripping].
If, on the other hand, the sealer starts to soften and become tacky – add a little more solvent, just enough to keep the mixture of melted sealer and solvent as a liquid for 5 minutes. After 5 minutes lightly scrape over the area with your paint scraper or flat screwdriver and look at the end of the material on the end – this will give you the answer.
If the sealer is solvent based it will become a liquid and nothing but a liquid. It may be runny or quite thick, but it will be a liquid. This shows that the sealer has totally dissolved. As the solvent now evaporates, you will see that the sealer gradually becomes more and more tacky and will eventually it will dry completely. This result shows that the sealer is solvent based and, therefore, totally compatible with our sealers.
If, on the other hand, the sealer does not dissolve completely and just softens there will be a soft deposit or gel on the tip on the blade of the scraper or the tip of the screwdriver, but it will not be a liquid. As the sealer has softened or not dissolved completely this indicates that that the original sealer is a water based sealer. The sealer will remain soft and not set to its previous hardened state. This indicates that our sealer is not compatible with the DIY sealer used on your paving.
If using InvisiSeal you will need to strip any existing sealer as InvisiSeal is an impregnator and any pre-existing seal will reduce its ability to penetrate into the paving