Replica Tape: Unlocking Hidden Information

From JPCL, July 2015

by David Beamish, DeFelsko Corporation

A surface profile is composed of a complex pattern of peaks and valleys. This article explains a developing technology that allows for extraction of useful information from replica tape, beyond just peak height....
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Tagged categories: Quality control; Replica tape; Surface preparation; Surface Preparation; Surface preparation equipment; Surface profile

Comment from Kevin Schweikhart, (8/2/2015, 10:23 AM)

Thanks Dave for continuing to improve our industry with your research, your writings and your products.


Comment from Mark Puckett, (9/1/2015, 12:01 PM)

interesting but Im curious what happens when you blast over existing profiled steel from previous profiled areas painted over...creating specifications for additional testing is nice but even better to know if those specifications are even achievable in the most dominate use area


Comment from David Beamish, (9/3/2015, 3:49 PM)

Our testing did not include surfaces that had been blasted twice, say, to reduce a too-high profile or to remove coatings from surfaces that had been blasted before. We hope that formulators, specifiers and blast media producers will use this field instrument to conduct research into these very issues, and others.


Comment from Harry Wilke, (9/9/2015, 12:33 PM)

Similar question - Abrasive Blasting with recycled LG 50 Steel Grit. One would expect the resulting profile to be in the 2.1 mil range. Yet we are seeing 3.9 - 4.4 mils. This can only be attributed to pre-existing surface profile. I tend to use the KTA-Surface Profile Comaparator and photograph these one the actual surface along with my replica tape measurements. This way I report the profile height as measured and evaluated visually. The high definition photographs reveal a remarkable amount of information when zoomed.


Comment from Marius Hamza, (10/23/2015, 10:08 PM)

The article is very interesting extremely well documented. I really enjoy reading it while having my morning coffee.


Comment from William Guan, (10/25/2015, 11:04 PM)

It is a very interesting idea of using replica tape and 3D image for peak density. I myself contributed to Mr. Roper's study by providing him the polyurethane coated samples on steel panels with different peak counts and also conducting some tests for his program. In general, my experience of using replica tape was not very great for 3 reasons: 1) the tape measured maximum peak depth rather than average; 2) the error % of the tape is so significant that the measured number might not be a true reflection of the actual profile depth (if one reads the fine printing of the tape manufacturer's instruction on the error of the tape, one could understand what I meant); and 3) the result depends on how hard the tape was pressed while doing the measurement. Quite be honest, I trusted what my finger's feel after touching a blasted steel more than what the replica tape would tell me. Therefore I was supporting Roper's idea of using stylus rather than tape in his study. I will be interested in seeing more data to support the accuracy and correlation of peak height/peak counts from the 3D tape measurements.


Comment from David Beamish, (11/8/2015, 1:26 AM)

Replica tape does indeed measure the max profile depth. More accurately stated, it measures the average of the maximum peak-to-valley distances. This relates closely to the values given by surface roughness instruments (drag stylus) and ensures protective coatings cover the maximum peaks. The % error in the tape is well known now and can be reduced by averaging 2 readings, 1 for each grade of tape. This error can be fully corrected with the use of digital micrometers that linearize the result. Burnishing pressure concerns can be alleviated by pressing lightly and ensuring both and x-y motion an a circular motion for 30 – 40 seconds.


Comment from Adrian Grace, (12/22/2015, 5:00 PM)

I come from down under in Australia. I value this quality publication for helping me keep up to date with our industry. I fully endorse their choice of Defelskos replica tape reader as top feature in 2015; it is an innovative product that will help us improve coating life in the future; thank you David Beamish & Paint Square for supporting our industry.


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