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Frequently Asked Questions

Below is an archive of questions that we regularly get from our customers. Knowing which Tenax products are the best choice for a given scenario can be helpful. If you have a question that is not listed below, feel free to contact us at: info@tenaxusa.com

To see the answer to a specific question, click the question below.

Can Polyester be used outdoors?

Polyester resin are by nature very rigid glues that once cured don’t give way to expansion and contractions due to different temperature variations. Although they can sustain pretty high temperatures before they start softening and eventually melting, the polyester tends to be very brittle when exposed to below freezing temperatures. This will make them prone to delamination if used to glue stone together. Epoxy resins instead are better suited for outdoor applications. Their chemical composition is such that they are more elastic and can expand and contract with the stone through the changing of seasons.

What is the best adhesive to use for fireplaces?

Polyesters can sustain temperature of up to 212 °F without losing its characteristic. It is important though that the glue itself is not exposed to direct flame. If the stone will reach more than 212 degrees we recommend using only mechanical anchors. Epoxy should instead be avoided, because although it is stronger glue than polyester, the maximum sustainable temperature is only 65 °C or 149 °F. Above this temperature the glue will start to soften up and potentially lose its structural strength.

What should I use for laminating?

To laminate granite Tenax recommend different products: If an epoxy is preferred the product of choice is the Epoxy Resin Strong Edge. This is a transparent 2:1 ratio, medium time setting, epoxy resin.

If a faster speed is required we recommend a premium polyester like Polytenax or Crystal knife grade. The use of regular polyester transparent, although mainstream in fabrication lamination due to its ease of use, fast cure time, and less expensive cost, it is to be used with caution, since especially on granite the high concentration of silica and quartz might have an inferior strength then a higher quality glue. The use of colored polyester resin in granite is highly discouraged, since the glue has fillers in it that will diminish its natural strength. These polyester resins can be safely used only on engineered stone (where Tenax has developed a complete line of pre-mixed color that will match the main quartz surfaces on the market) and on marbles.

What should I use for the seams of a countertop?

Seams usually are joined together using a regular polyester glue. Tenax manufactures one of the strongest polyester on the market. Its commercial name is Knife Grade Tixo and Knife Grade H. Premium polyesters like Crystal or Polytenax can also be used for Granite and Marbles. For white marbles instead we recommend Glaxs resin, since it is the only glue that will not leave an unappealing "wet" joint around the seam.

Can I use polyester colors with epoxy glue?

Coloring paste are usually pre-mixed part A resin with the color oxides. It is a good practice to use polyester coloring paste with polyester glues and epoxy coloring paste with epoxy glues only. If necessary you can use the Universal color made with an epoxy resin in the polyester mixture but not the other way around. Epoxy glue is a more precise chemical reaction and adding a polyester substance might create a problem for achieving the best final results.

What is a good way to estimate how much hardener to use with my polyester glue?

The right ratio in weight between the glue and its catalyst is 3%. We recommend the use of a digital scale the first time to make sure you calibrate your "eyeballing measurement". If a digital scale is not an option then a good rule of thumb is: A grape for an orange

Do I need to have the exact ratio for epoxy glues or just get as close as I can?

For epoxy resin the right Ratio is extremely important. The ratio recommended for an epoxy should always be measured with a digital scale. Guessing in volume might reduce the accuracy of the final mix and leave you with a non-complete cure of the mixture. For Tenax epoxy systems the part A is always assumed to be 100 parts and the corresponding part needed in weight of part B is specified in the name of the product itself.

If you are using for example the resin 5040 together with the BM40H hardener, you would have to measure 100 parts (grams works best to use on a digital scale) of part A and 40 parts of part B. Be careful of not assuming that 40 is referred to the percentage of the total amount but to the percentage of the part A. Meaning if you want to mix 100 grams total of epoxy part A will only weight 30 grams...

What is the strongest epoxy that Tenax makes?

Tenax makes different epoxy glues that will give you the strongest results when joining together 2 different pieces of stones. Domo 10 is one of the strongest epoxy available on the market. Its other main characteristic is that it contains an ammine that allows the Domo 10 to be used also when the material to be glued together is still wet. To break it apart you need a force of about 10 MPa or about 1450Psi. If instead a transparent (water clear) glue is needed, then Tenax Strong Edge would be recommended.

Can Tenax epoxies be used for underwater applications?

Once cured both epoxy and polyester glue can be submerged underwater.

What is the difference between "H" polyester knife grade and "Tixo" polyester knife grade?

Both Tixo and knife grade H are made with the same basic raw material. The major difference between the 2 is the Appearance. The reason why they look and feel different is in the way they are manufactured. Knife grade H is what is used in the majority of the rest of the world. It is made by a "warm" process, where after the glue has been made it moves freely in special tubes until it is poured in the cans. There it slowly solidifies and becomes the knife grade consistency we are all aware of.

Tixo instead is made with a "cold" process, where it is extruded from the reactor and "pushed" into the can. This process, although it leaves the glue softer, it also reduces even so slightly, the chemical strength of the products and the transparency. On the contrary the H, although is stronger and more transparent it has the characteristic of having little bubbles of air trapped in the surface leaving it a little bit gritty at touch compared with the Tixo. But by simply mixing it for 1 minute will eliminate the bubbles.

Should I use Tixo or "H" if I need a knife grade?

There is practically no difference in performance. This strictly comes down to preference and personal taste.

Tixo is a little smoother H is a little thicker. Click Here to see a video of the difference.

Both Tixo and knife grade H are made with the same basic raw material. The major difference between the 2 is the Appearance. The reason why they look and feel different is in the way they are manufactured. Knife grade H is the most popular Knife grade that is used around the world. It is made by a "warm" process, where after the glue has been made it moves freely in special tubes until it is poured in the cans. There it slowly solidify and becomes the knife grade consistency we are all aware of.

Tixo instead is made with a "cold" process, where it is extruded from the reactor and "pushed" into the can. This process, although it leaves the glue softer, it also reduces even so slightly, the chemical strength of the products and the transparency. On the contrary the H, although is stronger and more transparent has the characteristic of having little bubbles of air trapped in the surface leaving it a little bit gritty at touch compared with the Tixo.

Can I laminate with Polytenax?

Absolutely. Polytenax is a top of the line polyester that is safe for laminating granite, marble and all other stones. It is really fast and is one of the strongest polyesters on the market.

If Domo is exposed to sunlight, will it get brittle and fail?

Like any epoxy Domo 10 is not UV stable. That only means that its color will change with exposure at the UV rays and will darken up. Sun doesn't affect its strength though and its chemical and physical characteristics will stay the same.

Can I resin a slab or countertop in my own shop?

Yes but is not an easy task. First of all you have to have a means of repolishing the slab like a single head or "manettone" available. Also you will need some space to lay the slab down when waiting for the resin to cure. Most importantly you will need a working environment with a temperature of at least 75 °F and very low relative humidity in the air (20% is recommended).

Tenax Makes epoxies with a 1:1 and 2:1 ratio: How do I Choose?

Epoxies have very different ratios depending on the chemical composition and formula. All epoxies must be mixed with a certain degree of precision to be able to set correctly.

The ratio given is always intended in weight and not in volume.

To have less chance to make mistakes, especially for those customers who like to "eyeball" the right amount of part A and B, Tenax formulated easy to mix 1:1 and 2:1 ratio epoxy glues. The more popular 1:1 ratios glues are: Domo 10 and Rivo 50. When using epoxy system for surface resin treatment instead, the ratios vary greatly. Dealing with Tenax epoxy, you must always assume the resin as 100 parts in weight and the hardener in the quantity implied in the name itself. For example if you are using the hardener BX35h, the right amount would be 35 parts for every 100 part of resin, while if you were using the BB25m the parts to be mixed would be 25 (100 parts A and 25 parts B). This must be weighted on a digital scale preferably using grams as a measurement. Adding more hardener to the mixture WILL not speed up the reaction but only leave the mixture incomplete, thus not allowing to properly cure.

The great thing about Tenax epoxies is that the ratio is already predetermined for you. Tenax manufactures different epoxies for different applications. Depending on the specific application that you are needing, simply select the correct epoxy for that application. The mix ratio will already be supplied with that epoxy.

Does Glaxs ratio really have to be so accurate? Do I really have to weigh it on a scale?

Unlike polyester and epoxy adhesives that allow a small "fudge" factor, Tenax Glaxs is a bi-component adhesive that must maintain an exact mix ratio. That ratio can be 100:70, 100:65 or 100:60. Like with epoxy the name of the material always refer to the correct amount of hardener for 100 parts of resin part A. If the ratio is not followed specifically, Glaxs will not have performed with the desired and specified results.

However, to assist you in this exact mixing, Tenax has created pre measured kits. They are either in a special 2 plastic can kit (400 grams total amount) or in pouch kits (100 or 200 grams size). These kits are designed for single job use. Simply, squeeze one end of the pouch to break the center seal that separates the A from the B and squeeze it all together and mix well for approximately 1 min. Tear the pouch at one end and squeeze out the Glaxs onto the stone application. Easy, fast, and mess free!

I opened a can of adhesive and it was hardened up. What should I do?

Do not use the adhesive. This is usually caused by:

  1. the adhesive being left in extreme temperatures
  2. the adhesive not being resealed tightly
  3. the adhesive not being used within the shelf life period
  4. after you used the can for the first time, the product was contaminated with some hardener

Please contact the distributor that you have purchased your adhesive from or contact Tenax at 1-800-341-0432

Why are stones resined at the factory or quarries?

There are a couple of reasons why factory’s and quarries resin slabs.

  1. Resins strengthen stone. This allows the slabs to come in larger sizes. It also allows very fragile stone that would simply fall apart come to market as it consolidates and strengthens the material.
  2. In a typical mountain of stone, there could only be 20% of A grade material, 30% of B grade material and 50% of C grade and worse material.

By resining the stone, a factory or quarry can improve the quality of the B and C grade material to A grade allowing greater yield out of the mountain. This, in turn, allows for more stone production and lower prices for slabs. This is just 2 examples of the logic behind resined material.

Can Tenax Glues, Sealers, and other chemicals be shipped by Air?

Chemicals are not very friendly for the sky. Government regulations require that all corrosive and flammable materials be properly labeled for air shipments.

These are considered hazardous materials. It is possible to ship them by air when properly packed and only in certain amount depending on the hazmat classification. The distributor must also have special training and hazmat fees will be charged in addition to regular shipping fees.

There are only a few items that Tenax manufactures that can be shipped via air without hazmat fees: Color paste, Glydex and Ager H20, as well as Tenax Abrasives, etc. There are times that a project is extremely urgent and product must be received ASAP. Please contact Tenax and we will connect you with the nearest distributor that can provide the product as soon as possible. If an air shipment is necessary, Tenax can connect you with a distributor is approved to ship Tenax products by air.

Why does Tenax Crystal use the water droplet hardener?

Tenax manufactures products for very specific applications. Tenax Crystal , in flowing and knife grade consistency, was designed to create a very clear cure. This allows the application of Crystal to be used in filling chips and holes as well as producing clear seams where a color is not preferred.

When hardener and adhesive is mixed together, a chemical reaction occurs, allowing the adhesive to cure. In traditional polyesters using the white hardener, the chemical reaction is very fast and generates a lot of heat. This heat turns the adhesive a yellow color. In general, the faster a polyester chemical reaction occurs the more heat is generated and the more yellow an adhesive turns. This reaction takes place within 6-15 minutes.

Crystal uses the water droplet hardener or MEK. The water droplet, designed specifically with the Crystal chemical makeup is designed to drastically slow the cure time, and heat, of the chemical reaction. This allows the Crystal to cure slowly without as much heat. This keeps the Crystal nice and clear after curing. Crystal takes approximately 2 hours to cure at 80 degrees F.

I applied the hardener to Crystal but it will not harden, Why?

Crystal is a slow curing adhesive. There are several things to check:

  1. Was the correct amount of hardener used? Unlike the white hardener used in polyester, a correct 2-3% in weight of hardener must be used. The best way is to use a small scale to weigh out the Crystal and apply the correct percentage of hardener.
  2. What is the temperature of the air and stone? The cure time is based upon 72 degrees. If the stone or air is colder it will slow down the cure time.
  3. How old is the hardener? MEK tends to have a shorter shelf life then crystal itself. Always make sure you have a fresh batch of hardener when using water clear products.

What is the difference between Rivo 15 and Rivo 50?

Rivo 15 and 50 are very closely related. They are both the same color, come in the same size containers and have the same 1:1 mix ratio. Both are structural strength epoxies. The main difference is cure time: Rivo 15 as a gel time of 15 minutes in bulk (where the 15 comes in) and cures in about 90 minutes. Rivo 50 as a gel time of 50 minutes in bulk (yes also where the 50 comes from) and cures in about 150 minutes. This change in gel and cure times allows flexibility in applications. In thin layer the reaction speed is slower and like any other epoxy the reaction will not take place at all below 60 °F. To speed up the reaction heat must be used to warm both the product and the stone.

What is the difference between Epoxy Gel and Micto?

Tenax Micto is a fast water clear flowing epoxy with a 1:1 mix ratio. It cures in about 15 minutes. It is designed to fill cracks as well as be a structural adhesive. It can be used for laminating. It is considered an "emergency" glue, used to patch or fix stone when speed and strength are a must.

Tenax Epoxy Gel is a bi-component epoxy designed for gluing , laminating, and seaming stone. It is a knife grade consistency. 2:1 mix ratio. Gel time in about 5-10 minutes and cures in about 1 hour.

What’s the shelf life of polyester and epoxy adhesive?

Many things can change the shelf life of an adhesive. Where is the product stored? Is it exposed to extreme temperatures? Has the can been opened? What is the humidity where it is being stored? Is the can be exposed to direct sunlight? All of these questions can drastically change the longevity of both polyester and epoxy adhesives. In general, if an adhesive is stored between 65-77 degrees and kept away from direct heat, humidity and sunlight, an adhesive will have a shelf life for at least 1 year.

What is the difference between polyester and epoxy glue?

Polyester and epoxy glues are 2 different families of products and have different applications. Polyester is designed for to repair, rebuild, bond, and fill stone. Polyester cures more quickly, usually in about 15 minutes, is polishable, and colors easily. Polyesters become very rigid and since its structure won’t allow the usual expansion and retraction of the stone during freeze-thaw cycle, it is strictly for indoor use. Some polyesters are not UV stable. Polyesters come in a variety of colors and consistency.

Epoxies are instead designed to be structural adhesives. Epoxies can bond to almost any surface. Some may even be used on both wet and dry surfaces (like DOMO 10 or Kotor20). Epoxies bond the stone so strong that the stone will break before the bond will. Epoxies may be used in both indoor and outdoor applications since they are generally more elastic then polyesters. Epoxies generally take 2 to 24 hours to cure. Epoxies are VOC free but they are not UV stables.

These are the general features and functions of polyester and epoxy adhesives. For both of these adhesives, Tenax manufactures a variation of products that push outside these boundaries for specific applications. For more information please visit the polyester and epoxy category pages. Or you may contact us