Epoxy application - is masking tape the answer to clean, sharp lines?


It’s no secret I'm a big fan of taping. Clean, sharp lines make a huge difference to the finish of a floor, however there are a few things that can catch you out if you're not careful.

 To start with, getting the right tape is not as easy as it seems. As you may know, there are countless types and it can all be a little overwhelming. They all theoretically serve the same purpose, but as they say in the classics “oils ain’t oils”, and, in this case, “tapes ain’t tapes”. 

What’s the best tape to use?


When trying to select the best tape to use, I normally make the following comments -

  • Masking tape is a popular choice in the coating industry but in reality it is a weak paper-based tape with ordinary adhesion. It’s designed this way so it doesn’t pull off house paint when removed. This type of tape is cheap and commonly used, but it's not the right choice in all circumstances.
  • If you want to take a step up from masking tape, look for a tape known as “14-day tape”, manufactured by 3M. It's essentially the same thing, however it's more durable and sticks better.
  • If you want a really sharp edge on concrete, you must use tape with better adhesion still. I prefer using a cloth tape (aka “Gaffa” tape) as the adhesion is much better and there’s less chance of bleeding underneath.


Getting the best out of your tape


With the right tape in hand, better results can be turned into fantastic results if used correctly. Here are the tips I usually pass on in this area -

  • Pull the tape as soon as you can and while wet. Some contractors are happy to let the epoxy harden and use a Stanley knife to cut the tape off, but my preference is to pull straight away so I have a neat, straight line and less chance of bleeding underneath. The only time you should hold off is for thicker films that can self-level. In that case you want the coating to have at least gelled before pulling the tape to avoid it smoothing out and flowing past the tape line.
  • For contractors that don't like re-taping walls, you can be smart by using a two-step or “double tape” system. Apply tape and plastic/paper film starting 10mm/0.4” up from the floor, then apply a second round of tape along the bottom, a few millimetres off the floor. The idea being that you pull the bottom line of tape as you go and leave the taped plastic in place. This way, you have sharp edges where you need them and constant wall protection throughout the entire job.
  • Even if you’re using a cloth tape you can still struggle to get a sharp line if the profile of the surface is too rough, e.g. a house brick. With these surfaces you’re almost guaranteed to see bleeding underneath because the tape simply can't get into all the crevices. In these circumstances you’re probably better off carefully cutting in with a brush.

An epoxy floor coating bleeding underneath a tape line on bricks.

I think proper taping practices can be neglected sometimes because it’s the sort of thing that goes unnoticed on most jobs. One thing is for sure though, an ugly edge will draw attention and can cause a whole lot of grief. I was reminded of this on a recent floor where an otherwise beautiful finish was rejected because of some slopping taping and the contractor was forced to re-do the whole thing again.

What are your thoughts on taping? What tapes work best for you? Do you pull straight away or cut later on? Have you heard of messy edges leading to customer call-backs?

Take care and keep smiling,

Jack