There are some important considerations when line marking on concrete such as not line marking on newly poured or wet concrete, there are reasons for this, and some further advice is provided.
Advice on Line Marking on Concrete
Line marking on Newly Poured Concrete
Line marking on newly poured concrete is not advised. All paint manufacturers specify a minimum drying period of the concrete before painting. Concrete needs to cure for at least 28 days before painting. Can you see the arrow below? It clearly shows the paint lifting on the right-hand turn part of the arrow. This was newly poured concrete next to a much older slab. The only thing to do now is to grind off the paint and start again once the 28-day mark has passed. On the straight part of the arrow, the paint is holding beautifully because it was painted on concrete that had been poured more than 28 days prior to painting.
Line Marking on Wet Concrete
Another no-no is line marking on wet concrete. Here in SE Queensland we get plenty of rain, which is at times hard and sustained. It is so tempting to rush in and get your car park line marked as soon as we have a sunny day. We strongly recommend waiting until the concrete is less than 4% moisture content. The old rule of thumb was three good sunny days for the concrete to really dry out. At Linemarkers South East Queensland our crew will measure the moisture in the concrete before painting after rain. We will advise you if the reading is too high for safe line marking on concrete. If you go ahead while the concrete is wet, it won’t be long before the paint could start to peel.
Line Marking Wet Concrete on Kerbing and Pavers
If we are painting trip risk kerbing or an edge line near a garden bed or pavers, even longer might be needed because the concrete might stay wetter for longer.
Correct Line Marking Wet Concrete with Linemarkers South East Queensland
When quoting, Linemarkers South East Queensland will assess what surface preparation is required for your job, discuss this with you and will undertake this appropriately before the line marking begins. It may include water blasting to remove black mould and grime. This is generally done a few days prior to the line marking.
On the day of line marking, clearing the area and sweeping away debris is fine. However, please do not hose off the area less than 12 hours prior to line marking, because the surface could still be too wet to paint. As we have noted, moisture and line marking paint do not play well together, so sadly, the job will have to be postponed.
We understand that sometimes you absolutely need to get the line marking done regardless of the moisture in the concrete. This may be for a priority or safety reason. We are happy to oblige but will ask you to sign a release form, so you accept responsibility for any potential issues.
Additives to Concrete
Sometimes during manufacture, compounds are added to concrete to stop the concrete dusting, to speed up or slow down the cure time, harden the surface, and/or seal the surface to make it easier to slide pallets or cartons. This can affect the adhesion of paint. If you can, please let us know what additives have been used.
If there is any doubt, we would prefer to apply paint to a small area to test the adhesion. Recently we encountered a floor in a warehouse/distribution centre that had a wax additive that seems to penetrate several millimetres into the concrete surface. Even after grinding, the wax was still not allowing any paint to adhere to the concrete. Please see the photo of the yellow paint lifting.
Linemarking South East Queensland
Whilst these considerations may seem a little daunting, Linemarkers South East Queensland will work with you to ensure the best possible results when line marking on your concrete slab. When painting under ideal conditions the results are amazing – after a job well done by our crew as you can see in the photo on the left.
If you are in need of car park line marking or warehouse line marking Line Marking South East Queensland are experienced, providing the best quality line marking services including the above two services, and many more.