The Vellrath Group has made the application of UFP as simple as possible. To this end, the preparation of the substrate is limited to having a clean and sound surface to which to apply UFP. This usually does not mean excessive scrubbing or cleaning down to bare steel or any such thing like that but we do want the surface to be clean of any dirt, dust, oils or anything that might impede the UFP from attaching to the steel.
If your substrate is reasonably sound, or can be easily created, then the application of the UFP should be fine. In most cases a simple wipe down is sufficient to create the needed sound substrate. To further enhance adhesion, UFP has an additive encased within the mix to increase adhesion to the steel substrate. Comparing published adhesion reports, our UFP has 4 to 5 times the adhesion of your typical fireproofing. However, if there are blisters of paint, excessive dust or rust, wetness, oils or anything that impedes the bonding to the solid substrate, then it will not bond properly. A little common sense is required by the applicator.
Once the patch area has been prepared, it is time to mix the UFP material. Attached is our prepared mixing instructions, but in essence, take as much UFP material that you will need from the bucket and let us suggest you have taken 2 lbs. of UFP material from the bucket. To this, you will add about 2 pints of clean water – mix thoroughly. Now you are ready to apply UFP. A big hint we can offer is that applicators tend to mix too much water with the mix. What I have found effective is that of the 2 pints of water, hold some (maybe 20%) in reserve as you mix. As you continue mixing add slightly more water until you achieve a consistently that you feel you can trowel on easily. More times than not you will not use the full 2 pints of water. If you happen to mix it too wet, the consistency can be adjusted by adding a tad more of UFP material.
The goal is to get a thorough and consistent mix of wet UFP. You do not want any clumps or areas of dry mix in the bucket just prior to application. It should look like a textured taping compound consistency, maybe slightly wetter. Once mixed, you will have several hours to which to apply the wetted material. UFP is designed to be applied at the same thickness as the original material—with the assumption that the original material had been applied correctly itself. Another hint: I have always found that it is better to be slightly more generous with each patch application, say in the area of matching the existing thickness plus add about 10%. The cost of the additional UFP is negligible, but the cost to come back to recoat is extraordinary. The idea is to apply it once, correctly or even a tad bit generous, and move on. Coming back for whatever reason is non-productive by any standard.
A couple more helpful hints: in the laboratory we have learned to apply just over 1” of material in a single pass. Your specific field conditions may cause that to vary one way or another. A second hint is that if you suspect the original application is too thick or too thinly applied, The Vellrath Group has the capability to determine that correct thickness for a patch to a specific member. For a correct calculation we would need to know the application, column, floor beam, or roof beam; the size of the individual member, and the hourly rating. I do strongly suggest that a little common sense be put in play; for example, if the column has 2” of existing material, again for whatever reason, do you really want to argue that it was over sprayed and the original application should have only been 1 1/8”, over $.25 worth of material. Fill it and move on.