UV resin can be classified as a polymer that cures with UV light, making it flexible and having incredible resistance to chemicals, water, and UV rays. Whether you want to use it for your professional or artistic projects, it can be extremely beneficial, but on the other hand, sometimes you might come across a sticky outer layer after curing. Why does this happen?
When UV resin is cured, it might feel tacky to touch because it contains leftover residual solvents from the manufacturing process. It evaporates as time goes on but usually disappears after 24 hours of curing. This occurrence can often be referred to as “oxygen inhibition” and is the main reason why this happens.
Although this issue is often resolved, there are some cases in which this gooey texture may persist and might indicate that something else is going on with your product. This article will focus on covering this topic more in-depth, what are the main causes, how to fix it, what you can do in these cases, and much more information to get the utmost professional result.
What Is UV Resin?
Before discovering the main causes of sticky UV resins after curing, it is important to understand how this type of polymer differs from the rest and the proper curing it deserves.
UV Resin is a UV light-activated product that cures into an incredibly strong and solid plastic once exposed to UV Light. It hardens over an incredibly short time using a UV Lamp. The best thing about using this type of polymer is that there’s no mixing involved, but it can be one of the most expensive options on the market compared to the wide varieties of substances that can be used for a specific motive.
As we already mentioned, it can be used for different purposes such as: creating Dental appliances, Bottle caps and closures, Dental Crowns, industrial material used for bonding or coating, and Bridges Jewelry parts, to name a few.
This process takes place in two stages:
In the first stage, a UV light is directed towards the resin in order to “initiate” or start polymerizing. The second part, it’s placed right on top of where you’ve spread your UV resin.
Even though it sounds pretty easy, curing resin takes practice and experience.
Advantages and Disadvantages of Using UV Resin
Resin is extremely versatile, meaning that it can be used for several purposes.
UV resin is great to use in the dental industry and in other areas such as jewelry making, industrial adhesives/packaging/bonding, crafts, and graphic arts; in the automotive field and the industrial sector is one of the largest applications over the years.
Regardless of its incredible implementations in recent times across various fields, it has its advantages and disadvantages, which we will be listing.
Advantages
- The UV resin cures faster, in a period between a couple of seconds and minutes, compared to a two-part resin.
- There’s no need to mix the resin’s components which saves uptime.
- The polymer can be easily manageable, and there’s no need to stress about the process since the material only cures with UV light.
Disadvantages
- Not reliable and doesn’t last past six months after curing.
- Usually tend to be high-priced in comparison to regular epoxy resin.
- While working with UV resin, you need to work using thin layers and curing for every 3 mm coating applied. This means, in other words, the procedure can be tedious and time-consuming.
- You need a special UV light lamp to cure it since sometimes direct sunlight is not reliable.
Causes of Sticky UV Resin After Curing
Sometimes when working with UV resin, you might end up with a tacky outer layer after curing.
UV resin is UV sensitive, so it reacts with UV light during the curing process.
If you don’t use a UV lamp or sunlight to cure your material properly, the chances are high that an outer layer might remain tacky after curing.
This is why it is essential to work in thin layers and apply UV light to every coat used.
There are different causes of resin being tacky, but the main reason for this happening is improper application of UV light to cure every single layer applied.
Another reason why this might occur is due to a phenomenon called “oxygen inhibition.” UV resin can be inhibited by oxygen during the curing process.
This is because the UV light air bonds interact with oxygen molecules and limit how much UV energy can penetrate deeper into the material, which will prematurely finish your coating if not enough UV reaches deeper layers. Oxygen inhibition might also cause a sticky residue at first because there was too little UV used for proper application.
Even though this happens every time free radical polymerization is present, there are other factors to consider, such as the ability of a UV resin to cure with a dry finish solely dependent on the coating formulation and the wavelength power of the UV light.
UV lamps with a long wavelength power should be used for resins in order to cure the surface and leave no residue. They are best applied when they have already been properly mixed and stirred, at least until there is an even color distribution throughout (no streaks).
Using UV resin in its raw form without any mixing involved will cause the polymer with a short wavelength power to cure sticky, as it needs more time and heat from the UV light source for full curing. If this is not enough long exposure to the radiation, then some tackiness may be left behind after applying to the surface of an object.
In order to overcome these stickiness issues with your UV resin, you need to consider the following:
- The heat being generated by the UV lamp.
- Its exposure time and coating formulation.
- UV lamp intensity needs to be at least 4 watts to cure, and a Longwave UV which is the most useful type for curing UV resin as it penetrates deeper into the object being painted or coated with UV.
How Do You Fix Tacky UV Resin?
As stated earlier in the article, sometimes UV resin can end up feeling tacky after curing. In order to fix this, you should consider the heat being created, duration, and UV lamp intensity.
In addition to these factors, if your UV resin still has tackiness issues once fully cured, then there are a few things you can do:
- You can sand off the sticky resin if the entire surface is tacky, and you will have as a result, a UV resin with a matte finish.
- If it feels like adhesive, you can recoat with another layer of the polymer and hardener.
- You can also use light coats of acrylic or gloss sealer spray to seal the sticky surface.
- For smaller spots, you can use a resin spray which can help with giving a glossy finish.
How To Prevent Tacky UV Resin?
There are various ways you can avoid sticky UV resin after curing, and here’s how:
- Measuring the resin and hardener correctly: needs to be the exact ratio.
- Mixing the polymer well or using old resin.
- Pay attention to moisture or humidity, which can contribute to the resin’s result after being cured.
- Using a powerful UV lamp with stronger watts.
- Cure the resin for a little bit longer, and you can finish it off by placing it in the sun to make sure that it is completely dry. It should take between fifteen to twenty minutes, but it is suggested to give it rest for at least three days.
Related Articles
- Why Are My Resin 3D Prints So Brittle?
- SLA Printer Resins
- Choosing SLA Printer Resin
- Resin Printer Speed: What You Need to Know
- How Long Does It Take For UV To Cure Resin?
Conclusion
After reviewing this topic more in-depth, it can be concluded that the reason why UV resin is sticky after curing can be attributed to certain factors like UV light, humidity, and how well you mix your ingredients together.
If possible, make sure to cure your UV resin for a little bit longer if it isn’t completely dry before using or further processing. When properly dried, the polymer gives off that glossy finish that everyone desires while also being more durable and professional-looking.
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FAQs
Why is my UV resin still tacky after curing? ›
Tackiness or stickiness may be noticed on the surface of some ultraviolet (UV) light-curable adhesives and coatings. This phenomenon, known as oxygen inhibition, is the result of atmospheric oxygen inhibiting the cure on the surface layer of the polymerizing material.
How do you make UV resin not sticky after curing? ›You will need to use UV resin in thin layers and cure them in layers not more than 5mm. And you will need to have a stronger UV lamp at least 36 watts or cure them for at least 5-10 mins under a weaker light source. The way to remove the sticky pieces, put them under the sunlight for a day or two.
How do you tell if UV resin is fully cured? ›It might take a bit of practice, but visual assessment is still the most reliable way to tell if your resin print has been fully cured. Uncured resin has a glossy appearance. As the resin is cured, it takes on a more matte finish.
How long does it take for UV resin to not be sticky? ›It will take seven days for a full cure, but you can handle your project at this point if you are careful. It may scratch or dent (not ding) if you aren't gentle enough. If you are using a slow-curing epoxy, allow it to sit for 48 to 72 hours to be touchable. There are such things as quick-curing resins.
Can you overcure UV resin? ›Yes, it is possible to overcure a resin 3D print just as easy as it is to undercure it. Here are the factors that can influence your resin 3D print's curing time: Size: Larger resin models require a longer curing time than small ones.
Why is my UV resin not curing hard? ›MY UV RESIN PIECE IS NOT CURING:
If you've added a lot of opaque tint or other inclusions like glitter that are completely blocking the UV rays from reaching all parts of the piece, it will not cure. If you don't have any parts blocking the light, perhaps try curing this in direct sunlight.
Isopropyl Alcohol, Denatured Alcohol, Acetone, Lacquer Thinner.
What removes sticky resin? ›Resin should be removed with a rather aggressive solvent, such as one that is MIBK (methyl isobutyl ketone) based. Acetone or lacquer thinner also work but are extremely flammable. Never use solvent directly on your skin.
Will sticky resin ever cure? ›You cannot leave the sticky resin, as it will not harden after time, it will remain sticky. You will have to either throw your item away or fix the problem. In order to avoid the problem all together make sure to do the following: You must measure out your resin and hardener precisely.
Can you over cure UV adhesive? ›To test for thermal or UV aging of the adhesive, consider the cured adhesive as you would a plastic. Extreme over curing can degrade both plastic and adhesive.
How do you make a UV top coat not sticky? ›
So the tacky layer problem persists till the topcoat. To clear the residue on the topcoat, you have to use a lint-free wipe soaked in alcohol or use a No-Wipe Top Coat.
Why is my resin sticky after drying? ›Sticky, tacky resin
This is often caused by inaccurate measuring, not mixing thoroughly or by curing in cold temperatures. Try moving your piece to a warmer spot: if it doesn't dry, re-pour with a fresh coat of resin.
Be patient with curing time.
You can start to work with poured 2-part resin components after about 24 hours, but you should allow 3 days to allow it to really cure. For UV resin, it takes about 15-20 minutes to cure each layer under a UV lamp, and a few hours to cure in direct sunlight.
There are a few things that would definitely give sticky parts. The first step not to do is to rinse a part that is not completely clean with water. Water and resin won't mix and give a dirty, sticky surface. Next to water, post-curing not completely clean or dry parts will also lead to a sticky surface.
Why is my resin still sticky after 24 hours? ›Tacky resin is when your project has started to cure, but the surface looks and feels like the sticky side of a piece of tape. Under-cured epoxy resin typically happens when the chemical interaction between the resin and hardener didn't work properly.
How can I make UV resin dry faster? ›Warm-up your resin and hardener bottles in a hot water bath for about five to ten minutes. By warming the bottles, you can jump-start the reaction with extra heat. This will make the resin dry faster.
Does temperature affect UV resin curing? ›When your room temperature is too cold, the resin will take far longer to cure. If the temperature of your resin room is below 72F/22C, your resin may stay sticky for days or may not cure at all.
Is UV resin safe once cured? ›Some photoinitiators in common 3D printing resins have a significant level of organ toxicity. As with most FDM materials, resins are not food-safe even in their cured state, so processes like SLA and DLP should not be used to directly fabricate products like food containers, cookie cutters, or drinking vessels.
Is UV resin food safe after curing? ›Is resin food safe? The answer is no. Substances may migrate from SLA parts which makes none of the resins and printed parts food safe by default.
Does humidity affect UV resin curing? ›While it might seem like a great idea to cure your resin in warmer temperatures, too much moisture in the air can affect your project's final result. If you're not careful, you might end up with a cloudy finish or an oily-looking surface layer.
How strong of a UV light do you need to cure resin? ›
A 36W UV lamp is more suitable for UV resin. Curing time varies depending on the resin and the lamp used. But generally, it is about a few minutes, even ten minutes for UV resin.
What does vinegar do to resin? ›White vinegar and baking soda are safe and natural ingredients that you likely don't need to leave home to find. The vinegar helps remove resin and wax easily (while killing any odor), while the baking soda acts as a water softener.
Is sticky resin safe? ›While fully cured resin is safe, liquid resin is toxic and should not be touched. Similarly, vapors generated by SLA 3D printing and curing can have negative effects with enough exposure. That's why you should always 3D print and cure SLA parts in a well ventilated space.
Will resin stick to already cured resin? ›Yes. Since the epoxy has cured a chemical bond is not possible so what is called a mechanical bond is needed. This simply means that the cured epoxy has to be lightly sanded before the next coat is applied: the first coat should have a matt, almost white, surface. Use glass paper of between 80 and 120 grade, no finer.
Can you touch resin after its cured? ›Once resin prints have been fully cured with UV light, they are safe to handle. Proper ventilation is also important when working with resin printers.
Can you Overcure UV gel? ›Over-curing a gel is possible. Some gels will discolor when over-cured and some will lose the gloss, while others will do both or neither. So much of this depends on the gel and the curing light. Each manufacturer should be able to assist the nail technician in what issues they may see with over-curing the product.
How thick can you cure UV resin? ›In contrast, UV resin is a 1-part resin that is instantly ready for use. Epoxy resin cures without any aids, UV resin only cures under UV irradiation. Its maximum layer thickness is 1mm.
What wavelength does UV cure adhesive? ›Wavelength Range of UVA
The wavelength for UVA spans 320 nm to 395 nm, making it the longest UV wavelength. UVA is used for general UV curing and is responsible for most of the adhesion properties for the UV formulations. Common uses for UVA include: Curing inks, coatings and adhesives.
Whether you're using a dark or light color, if this happens to you the first thing to look at is how thickly the gel polish was applied. If the polish is too thick, your UV lamp won't be able to cure it all the way. Thin coats are always better!
Is a UV base coat supposed to be sticky? ›Please be kindly aware that it's normal for each layer of gel nail polish ( especially base coat) to remain sticky which would give the next coat of polish something to hold onto. In the end, the top coat will seal it all in. Hence, you don't need to wipe off the stickness from base coat.
Why is my base coat sticky after curing? ›
My gel polish is tacky, is this normal? Yes, your gel will be slightly tacky to the touch after you have cured each coat. This is so that the next coat can properly adhere to the previous one. Once you have applied your Top Coat, you will need to wipe with cleanser to remove the tacky layer to finish your manicure.
Why is my UV resin not drying? ›MY UV RESIN PIECE IS NOT CURING:
If you don't have any parts blocking the light, perhaps try curing this in direct sunlight. In future pieces, try layering opaque or dark colors in thin layers and curing in between each layer.
How To Fix Tacky Resin: Try moving your piece to a warmer spot for 24 hours to see if it dries. If temperature was not an issue and your resin is simply tacky, count yourself lucky: this is the easiest fix of all 3 sticky situations.
Will tacky resin eventually cure? ›Resin starts to cure but does not go all the way completely. You should find a warmer spot to move your piece such as room or working office. If artwork doesn't dry, try to repour with a new fresh coat. Runny Resin: when the resin is not quite liquid or hard, the mixture will be left with a mess.
Will tacky resin ever dry? ›You cannot leave the sticky resin, as it will not harden after time, it will remain sticky. You will have to either throw your item away or fix the problem. In order to avoid the problem all together make sure to do the following: You must measure out your resin and hardener precisely.
How can I dry UV resin fast? ›Increase the temperature: The ideal temperature for curing ArtResin to 75-85ºF / 24-30ºC. Cure time is affected by temperature: warmer temperatures facilitate curing and colder temperatures slow curing. Place a space heater or heat lamp near your piece to encourage the resin to cure faster.
What happens if resin cured too quickly? ›The resin can cure too fast.
That heat builds upon itself and can speed up the reaction. Your resin may harden before you can pour it into your resin mold or coat your artwork surface.
Your resin needs more time to cure
While resin is curing, it turns semi-solid (think gelatin) but is soft and pliable. In other words, it looks like it's done curing, but it may not be. Double-check the cure time for your resin. If you're lucky, you simply need to give it more time to cure.
Craft Resin's cure time is about 24 hours (depending on the thickness of your project). This is the time the resin and hardener mix goes through the chemical reaction to form a solid. After 24 hours it still might not be completely solid, and can be slightly flexible.
How long should you post cure resin? ›In the best conditions—full sun and no clouds—it can take about two hours to cure a small 3D printed model in direct sunlight. Transparent parts will cure faster (in about half the time it takes a non-transparent part), while large prints can take up to 8 hours to fully cure.
What does tacky resin feel like? ›
Tacky resin is when your project has started to cure, but the surface looks and feels like the sticky side of a piece of tape. Under-cured epoxy resin typically happens when the chemical interaction between the resin and hardener didn't work properly.
Can we dry resin in microwave? ›In fact, selective heating with microwaves makes it possible to cure an adhesive while simultaneously cooling other parts of the substrate by external means. Several studies have examined microwave radiation as a potential heat source to cure epoxy adhesives.