Someone asked us the other day if it is possible to use a Polituff on cement walls cracks or what commonly called here in the Philippines as “Masilya.” Before we discuss this, what is Polituff?
According to Super Globe Inc., Polituff is a Polyester Body filler is a 2-component polyester body filler, BPO – catalyzed formulated to fill in surface imperfections resulting in a smooth surface prior to topcoat paint. It is an impact, shock- resistant putty especially designed for use on auto-body patching of dents, leaks, holes, and flaws.
As you can see from their definition it is designed for auto-body patching but I have witnessed this myself that there are plenty of skilled painters here that use this brand to patch up almost every material there use in construction like cement, wood, fiber cement boards, and metals. Looks like this have been a trend that almost all painters tend to use Polituff on cement wall cracks and other surfaces because they are saying it dries fast and much stronger material.
Those who use Polituff on cement walls may have done it perfectly after they have finished painting the wall but base on our experience, this will eventually backfire and may result in back jobs in your projects. Meaning a more lose in your construction knowledgeability, integrity, and profit. Read an article by Mamang Pintor where he shares his own experience on use Polituff on concrete wall cracks.
As to answer the question, it is to plan ahead your choice of materials. Read carefully what it is for before using it. There is always the best material for specific work or problems. That is why most paint companies have research and development groups to make solutions to every situation. For this problem, check out fillers use primarily for the size and scope of work. You can use a water-based patching compound or a skimcoat of it is only up to 5mm cracks but be careful to read the instructions for not all skimcoat can cover 5mm gaps. If its greater than 5mm, a cement mortar mix might be most useful. If you ant a specific filler for cement cracks, then maybe you might consider Boysen Masonry Putty or check out other brands. There is really plenty of them out there.
Cement cracking is normal. Shrinkage is the main cause of cracking. As concrete hardens and dries it shrinks. This is due to the evaporation of excess mixing water. This shrinkage causes forces in the concrete which pull the slab apart. As long as it is not a structural defect, it is normal.