Review on Lignomat Mini-Ligno E/D Moisture Meter by Michael Radhakrishnan

WHY MOISTURE MEASUREMENTS ARE IMPORTANT. Wood has the amazing ability to shrink when dry and expand (swell) when wet. I learned this the hard way about 25 years ago when I was building a beautiful rustic table out of planks of unknown moisture content. and after a few weeks I found that my properly aligned boards were shrinking and creating unsightly 3/16 inch gaps between them. It is reported that 90% of parquet installation problems are due to moisture levels. Usually the moisture level is nothing to see or see. feels tool-free and any mistake can be quite costly. According to the NWFA (National Wood Flooring Association), two conditions must be met: The moisture content of the hardwood and subfloor must normally be within the typical range for the area in which it is being installed will be within 6-8%, up to 8-13% in coastal areas The difference between the moisture content of hardwood planks and the subfloor should be within 4% for narrow planks and under 2% for wide planks Failure to do this may require maintenance HOW TO MEASURE MOISTURE There are two ways to measure moisture. Dry wood has a much higher resistivity (typically in the hundreds of megohms range) than wet wood (in the kilohm range). The second way is contactless. The wood acts as a dielectric between the two electrodes on the back of the gauge, forming a capacitor. High-frequency current (in the range of hundreds of kHz) flows through this capacitor and its capacitance (which depends on humidity) is measured. The advantage of a non-contact gauge is that it leaves no needle marks on the wood and can provide lower moisture readings than ohmmeters. However, measuring capacitance accurately is more difficult than measuring resistivity. Therefore, non-contact gauges are less accurate on the low end, but just as accurate or even more accurate on the high end than ohmmeters (but their price on the high end is really high). WHAT IS THE DIFFERENCE BETWEEN CHEAP AND EXPENSIVE? . This is the usual big question – buy a $30 or $300 moisture meter? What do I gain by buying the most expensive and what do I lose by buying the cheapest? My research on this topic revealed the following factors.1. All pin-based sensors use the same principle: they measure the voltage across the pins and the current flowing between the pins to calculate resistivity. To make this calculation accurately, you need to accurately measure current and voltage. Also, due to the high resistivity of dry wood, it is very difficult to measure at 6% or below. In the cheapest meters, you get the cheapest components (especially cheap analog-to-digital converters) and poor measurement accuracy. Consider this fact: even the best instruments rarely provide the accuracy needed to meet NWFA requirements. According to a statistical study by PJWilson published in Forest Products Journal in 1999, high-end pinmeters have an accuracy (standard deviation) of 1.5% for moisture content (compared to the 2% range recommended by the NWFA to 4 %). . I expect a lot more bugs with low level tools and some of them might be useless because they are so inaccurate.2. Moisture content can vary from the surface to the depth of the board. For example, a board that has been rained on may be wet on the top but dry in the middle. In order to obtain an average value, a penetration depth of the pen of 1/4 to 1/5 of the thickness of the wooden part is ideally required. Low-level sensors may not have pins suitable for deep penetration, while high-end sensors have stronger pins and pin holders, and often come with external pin holders (probes) connected via cables. Also, they often come with insulated contacts where only the pin tip is conductive; This helps eliminate the effect of surface conduction in the wood. This is very important in the wood processing industry. Fortunately, for typical hardwood projects where the wood is fairly dry, the difference between the shallow and deep penetration readings is usually very small. This mini Linho comes with two sets of pins for two different depths, 5mm and 10mm, but they don't seem particularly strong.3. Moisture levels depend on the temperature of the wood. Typically you get a difference of 0.5% for every 10 F (5 degrees C) of deviation from standard room temperature. The top-class measuring devices have a built-in temperature sensor and correct them automatically. Mid-range instruments come with a correction table. Low level instruments may use a standard calibration for a typical room temperature of 70F and have no correction at all. This mini ligno has no built-in correction, but there is a correction table in the manual.4. Depending on the type of wood. Typically, moisture meters use Pacific NW Douglas fir as the calibration reference and apply correction factors for each specific wood species (this must be entered manually, the instrument cannot tell which wood it is measuring). While native breeds are relatively similar, exotic hardwoods can differ greatly from Douglas fir. The good news is that at humidity levels below 10% (which is the typical range recommended for installation) the differences between most household types are within 1-2% humidity, which is roughly the error of the meter itself. Therefore, these differences in the range of 6% to 10% are often negligible. The higher the tool level, the more difficult the correction process. These inexpensive mini lingos like these group all 54 wood species into two groups, with the assumption that there is little variation within each group. Higher quality tools can divide types of wood into 5-6 groups. Finally, individual calibration for each specific wood species (up to 20-40 species) is possible. It's actually not that expensive for manufacturers to include a higher level of calibration detail in a tool (in some cases it's just the cost of the paper the conversion table is printed on), but it does add significantly to the price of the tool. Instruments with many types of wood listed individually. To leverage all that precision, you might also want deep penetrating (insulated) tips, built-in temperature correction, and possibly high-end electronics. price range. This benefit of high-end models comes with a complexity that most people might not like: imagine you're tasked with measuring the moisture content of a walnut. Well, with the advanced tool, you have a choice of African, American, European, New Guinea, and Queensland walnut (consider which one you have). Then you have to measure at several different depths. Make sure the temperature correction has been performed. Then average several readings. Will a regular user do it? I suppose that's why not everyone needs (or will use properly) the most accurate tool. Ability to store and average readings. It is generally recommended that several measurements be taken in different hardwood boxes or at different subfloor locations and averaged. High-end tools can do this for you. An unimportant factor for a DIYer, but can be useful for a professional. SUMMARY: This mini-ligno model appears to fall in the low-to-mid range of moisture meters. It has enough electronics to measure resistivity with reasonable accuracy for successful wood and parquet work. It has a very basic fix for wood species (two groups only). It doesn't have built-in temperature correction, but there is a correction table in the manual. It comes with two sets of pens, but it takes some work to change them. I'm guessing you can expect errors of up to 2-4% absolute moisture content (which means you can probably get a reading of 11% for wood with 8% moisture content). This gives a roughly acceptable accuracy for determining whether the wood's moisture content is in the NWFA range, and works well enough to check how well the moisture content of solid wood and subfloor match. the cheapest mid-range gauge you can buy to use as a reasonably accurate woodworking gauge. Lignomat is considered a trademark in the world of moisture meters and has been in business since 1975. The Mini-Ligno line is a low-end range of pocket gauges and one of the cheapest instruments in the Mini-Ligno range. It seems to be right above the bottom line that separates tools from useless toys with pins, glowing numbers, and buttons. It's not as sophisticated, accurate, or resilient to the rigors of everyday use as the high-end ($200-$500) models from Delmhorst or Wagner, but it's accurate enough for most common home plumbing and woodworking woods. Very easy to use (only one button is pressed). Due to the small size, it is very convenient to take with you. No big financial loss if you break or lose it. Relatively good value for people doing chores (although I'm still confused as to what's in there that justifies the $100 price tag). You still get what you paid for (on the relative humidity scale) (and readings can certainly differ by a few percent or more on less standard woods), but you might not even need more. for the standard task of determining whether hardwood and subfloors are ready for laying. I've seen them used by professionals and they're certainly good enough for DIYers. The higher quality Mini-Ligno models with the letter C have a connection for an external probe. For an additional $10 or so, you can purchase an S/D model that can also measure moisture levels in drywall (which can be useful for housing inspectors inspecting flooded buildings). corrected for 65 individual wood species grouped into 20 groups (and I suspect they may have more accurate electronic components as well). This increases accuracy by 1% or 2% on dry wood and even more on wet wood. The wood groups listed in the E/D and S/D guidelines include (no groups 1, only 2 and 3). ): Group 2: Abachi, Afromosia, Bamboo, Beech, Cedar, Kumari, Cypress, Dogwood, Gonzalez Alves, Ikoro, Jatoba, Koa, Black Locust, Oak, Poplar, Ramin, Rosewood, Teak, Wenge, Zebra, Fibreboard, OSB, waffle board. Group 3: Alder, Ash, Aspen, Balsa, Basswood, Birch, Cherry, Poplar, Cypress, Elm, Douglas Fir, Gum, Hemlock, Hickory, Kempas, Larch, Lauan, Mahogany, Maple, Meranti, Merbau, Myrtle, European Oak, Pine, mahogany, spruce, teak, tigerwood, walnut and chipboard.