There can be multiple reasons for soft spots or uncured patches in the coating, which can occur when using 2 pack paints.
Common Causes:
Poor Mixing – If paints are not mixed thoroughly, you may be left with veins of unmixed product throughout the tin. If transferred to a scuttle, this unmixed product can remain. It is unusual to see patches completely uncured if you have done this, however you may notice an area that is slightly softer or has a slightly sticky feel when the rest of the coating has fully cured.
Scraping the tin – No one wants waste as such, and so when transferring your paint from tin to scuttle, it may seem like a good idea to scrape the tin to get the most out of your product. This layer stuck to the side of the tin probably hasn’t mixed with the part B fully. If you do scrape your tin, ensure that you give your paint another mix with your drill & paddle whilst it’s in the scuttle (this is good practice anyway). This will ensure complete mixing.
Loading brush from the sides of the tin – It could seem efficient to load your brush with the paint stuck to the side of the tin in order to cut in your edges, however, it is unlikely it has mixed thoroughly with the part A. As above, it is better to scrape this into your main scuttle, give a quick mix in the scuttle and then load your brush direct from the scuttle. If you have a dedicated unit for cutting in, load your brush from the centre of the tin.
Contamination/Moisture – Certain chemicals can react with the hardener before the paint has chance to cure (this includes water). If this happens and chemicals come into contact with the coating during its curing process, you may get soft or uncured patches, alongside other undesirable effects.
Temperature – Temperature will have an impact on cure speed. If you have cold patches on your floor, they will take longer to cure than warm patches. The good news is that the paint should continue to cure and will eventually catch up with the rest of the coating. This is one of the main reasons we recommend not applying our paints below their stated minimum temperature. Please DO NOT be tempted to introduce heat by means of an open flame heater, as these will introduce their own issues.
So, how would I resolve this?
- it may be as simple as waiting for the temperature to increase a little and waiting for the curing process to fully complete.
- Unfortunately, if the issue is not temperature related, then you will need to remove as much of the soft/uncured paint as possible, by means of scraping, abrading and wiping away with a suitable solvent.
- Once the area is cleaned off and dry, ensure the entire area has a good key surface (sand/abrade if needed).
- Proceed to apply another complete coat of product, ensuring all guidance is followed.