Thinking about purchasing a domeless nail? Already own one? Read ahead, this information is for you.
Domeless nails can be a great. When it all boils down to it, it comes to convenience and function. They are convenient because you don’t have to take a sticky dome off and put it back on every time. They function great because you can have larger diameter heads with more mass/surface area which needn’t fit within the constraints of the ground joint of your dome. For these reasons the domeless nail has gained popularity over the years and doesn’t seem to be going anywhere any time soon.
So whats the big issue with domeless nails? Why do people ever have issues with them?
Let’s start from the beginning. The biggest dilemma that I ran into while designing domeless nails was that glass and titanium have a very different coefficient of thermal expansion. “Thermal expansion is the tendency of matter to change in volume in response to a change in temperature. When a substance is heated, its particles begin moving more and thus usually maintain a greater average separation.” -Wikipedia (sorry for citing Wikipedia Professor White)
Thanks to science, we can look up these thermal expansion coefficients.
Borosilicate glass is known for having a very low coefficient of thermal expansion (3.3 x 10−6/K). Titanium has a relatively higher coefficient of thermal expansion (8.6 x 10−6/K).
What this means is that titanium expands with heat and maintains a greater average of separation than borosilicate glass. We figured this out early in R&D as our first attempts at creating domeless nails would crack the female joints they were inserted into. Realizing that if we moved the titanium to the outside of the joint, instead of on the inside, the expansion of the titanium would cease to be an issue; or so I thought. Moving the titanium from the inside of the joint to the outside certainly solved the issue of the the joints cracking, but it birthed a whole new issue of its own (albeit a lesser evil): the joints sticking.
Now the reason they became stuck is because the titanium sleeve is tapered to match the taper of the glass ground joint. At room temperature they sit together fine, and can be removed easily. Once taken to a high temperature, the titanium begins to expand and since gravity is actively pulling on the nail, the nail slides a couple nanometers down the taper of the glass ground joint. As the nail begins to cool, the titanium begins to contract back to its original size, only it is now further down on the ground joint then it was ever capable of being at room temperature. This creates a pinch and makes the nail clamp down on the glass. Not enough to damage it, but enough to make it very difficult to remove if you don’t understand how to remove it.
To remove a domeless nail you will need to get the domeless nail equally as hot as it got during its peak of use, if not a few degrees hotter. This can be done by heating the head of the nail extensively and allowing time for the heat transfer to reach the sleeve. Once the nails sleeve has become hot enough use pliers or protective gear to grab the nail and remove it. It should remove with the slightest force. IF IT DOES NOT REMOVE VERY EASILY IT HAS NOT GOTTEN HOT ENOUGH. DO NOT ATTEMPT TO FORCE THE NAIL OFF. The stress from the force is more likely to break your glass than anything else so do not force anything. If it doesn’t come off easily apply more heat. Torching the sleeve directly will not break the glass (believe me I’ve tried) and can speed the process up, but when you torch the sleeve directly you risk cooking any residue which may reside on the inside of your glass ground joint. When you cook residue on the glass it leaves burn marks which are hard, if not impossible, to remove. It’s best to heat the head and let the heat transfer to the sleeve to avoid this.
Preventing the domeless nail from getting stuck is very simple. We now know that it only gets stuck when it is allowed to cool down with out interference, so simply add some interference. When the nail is still warm but cooling down, use your dabber to give it a tiny bump back up the ground joint. Do this once or twice. It is simple and easy to do. The hardest part about it is just remembering to do it.
The one piece domeless nails (14mmV2, 10/11mmV2, DualiTi) are the worst offenders of getting stuck as the heat transfer to the sleeve is the greatest. The InfiniTi nail greatly reduces the getting stuck issue as the heat transfer is broken between three (or more) pieces. This “broken heat transfer” is also how we were able to make the InfiniTi insert into female glass ground joints for use without cracking. Watch this video of the InfiniTi nail attempting to crack ground joints.
If you are concerned but still want to use a domeless nail you can get a glass “safety adapter” for use in between your piece and your domeless nail. Speaking for myself, I have used my InfiniTi nail on a 14mm male joint since I finished the design, with no adapters and I have had no issues.
In conclusion, I considered discontinuing the domeless nails back in the beginning because of this getting stuck issue. I didn’t want a product on the market to reflect us in a bad light, and I admit it does slightly. The reason I decided not to discontinue them in the end is because the convenience and the functionality of the domeless outweighed the inconvenience of a temporarily stuck nail; at least to me and several other heads in my circle it did. It was all we used, even in light of all the evidence, it stayed with us as a part of our family. So I let it stay on the market as our mantra has been “If we like to use it, they’ll like to use it”.