Why the plywood grade is so subjective ?Plywood QC job inspection,Let me explain to you.
Entered in the plywood industry since the first day I graduated from college, worked many different leading roles in plywood industry ,experienced so much in the past 9 years working experience.
Many buyers just sent their suppliers the traditional normally called “INQUIRY” with grades and other specifications about the plywood they import ,very few have exact accurate quality description of the plywood they are looking for or using ,if more questions about the plywood grade from the suppliers they just simply answered HPVA or IWPA something like that the international grading rules.
Plywood is very simple but very complicated .Plywood grade is very subjective .What visual and un-visual qualities define plywood as grade is a matter of subjective perception and opinion, experience and sizes, moisture contents, density are normally objective measured by the professional machines.
While appearance evaluations ,inside core veneer and veneer core quality and the associated grade classifications differ somewhat from mills to mills, all are generally based on the standards set by the exact certain buyers ‘s quality graders and inspectors.
Like HVAP and IWPA or GCC or MIDDLE EAST MARKET GRADE These standards are established as a baseline for objective evaluation, but it is important to note that the grading process is also a subjective process. For this reason there is no substitute for ongoing communication between the mills and the customers to establish parameters of grades that meet the customer’s needs. In some cases, this may require establishing a customer specific grade, which is entirely acceptable within the industry.
Everyone of these types of plywood have a completely different grading system. Everyone also has many different grades within it’s own category.
Every mill has a quota to meet on each grade. Every type is graded by human eyes, but not every plywood .When the shifts change a different set of eyes grades the plywood. Mills produce sometimes hundreds of thousands of pieces of plywood a month. So they can not be grading each piece. In other words the grading of wood is very subjective.
Everyone of these types of wood have a completely different grading system. Everyone also has many different grades within it’s own category.
Now for what they do have in common – Every type is graded while they are being manufactured on high speed equipment. Every mill has a quota to meet on each grade. Every type is graded by human eyes, but not every plywood. When the shifts change a different set of eyes grades the plywood. Mills produce sometimes hundreds of thousands of plywood monthly. So they can not be grading each piece. In other words the grading of plywood is very subjective.
So with that said let me explain about the grading system of our plywood.
I have been inspecting ,checking and buying and selling every type of plywood for more than 9 years . I have inspected many thousands of containers of plywood. Just because it says it grade B/C, grade C/D, grade B/BB, grade BB/CC or any other grade doesn’t mean a lot. I have seen the so called best grade of plywood look awful and the middle grades look perfect. Many times when you cut the metal bands on a unit of plywood the top pieces are on grade and the middle pieces are off grade. How many of you have been to many different plywood production manufacturers buy some plywood which they state are a C grade only to find it full of knots & splits but on your next trip every board is fine. They really were the same grade, it’s just how they are graded that makes the difference. Remember every type of wood is graded by humans… and not each plywood either.
There are different grades of plywood depending on the composition and quality of the materials used.
The quality criteria for grading plywood are determined not only by the Plywood association also by the exact certain importers or buyers already . This criterion is also used for determining types of hardwood plywood.
The purpose of the grading system is to give distributors, manufacturers, general contractors, carpenters, architects and do it yourself enthusiasts commonly understood parameters that define the composition and quality of the materials that comprise the plywood.
Each plywood grade can vary within the grade due to the wide differences in the natural characteristics of different plywood species. These differences include the grain and color of the plywood.
Another reason is that hardwood plywood grading is on an aesthetic basis, making grading subjective from grader to grader. However, a general rule of thumb is the lesser the defects the higher the grade will be.
According to my limited experience and my CHINESE-English problems,I also found some similar experience in grading plywood ,some of their IDEA meaning or words I copied their THINKING and EXACT ACCURATE WORDS to describe my FEELING AND EXPERIENCE AND WORDS EXACTLY AND ACCURATELY.This is a combination of my experience and their accurate professional words and thinking.