Heat Debossing Leather

[lwika16]

Hi,

I'm trying to troubleshoot branding my logo into an oil tanned leather. When I brand it in I'm using my Kwikprint 55 machine with magnesium dies, temp set at 450F and dwelling for almost a minute. The branding turns out great at first but if I wrinkle around the leather at all, the nice dark area just disappears. It's like I just can't burn the leather enough, even at that high heat. Any thoughts?

Thank you in advance,

Lori

[Hardrada]

Higher temperature?

Chrome tan is like that: I've also found it's hard for it to take an impression. Frustrated, what I've ended up doing is making patches with my logo on veg tan and then sewing them to the chrome tan project.

[toxo]

What does "wrinkle around" mean Lori?

I'm building an add on heat block for my arbor press. It's not wired up yet but I'm hoping three 120W heaters will do the job. My brass letter set arrived a couple days ago and I had a little play. I exchanged the bar for a slightly longer one and after leaning on some dry veg tan for about 20 seconds I was impressed with the depth. I've wondered how it will perform on oil tan but won't know till it's wired up. I'm thinking more foiling rather than branding but I can't see oil tan liking foil.

[lwika16]

Hardrada, I've thought about doing the same, my only concern was whether or not the oils from the oil tanned leather could seep into the vegetable tanned leather and make it blotchy. Have you had any problems with this long term at all?

I can't go too high with my Kwikprint, otherwise the thing starts smoking! 

 

Toxo, by wrinkle around, I mean bending it back and forth...

[Hardrada]

Yep, I was a bit diffident about suggesting upping the heat since you mentioned your dies are made of magnesium which is explosive when exposed to flame. I still gave the suggestion thinking that the machine manufacturer would have factored high heat into the safety threshold for his product, and also that the heating is electrical. I use brass stamps which are not inflammable, and an alcohol lamp to heat them, and an arbor press to stamp.

Alas, I can't report on long term results, as I don't have years in this. Maybe it depends on the use?

Heck, my problem probably is the stams not being hot enough:

Edited February 27, 2021 by Hardrada

[Matt S]

@lwika16 Lori, how hot can your machine go? I'd just turn the temperature up a bit and give it another try. Magnesium takes a lot of temperature to burn, in school we had to hold it in a gas jet for a length of time to get it going. I think you'll be safe turning it up. In fact, I just used the Google. Magnesium autoignites at 473 °C (746 K; 883 °F). You're pretty safe making it hotter. Maybe don't use a blowtorch on the die though! 

Most of the chrome tanned leathers I deboss get a deep, permanent mark at around 200C (390F) but I guess the amount of oils in yours might be doing something odd. A minute is a long dwell time, what happens if you dwell for a few seconds?.

[lwika16]

Thank you for the info Matt.

My machine goes hotter, but according to the manufactuer, it's not really good for it to go much above 450F. I just came to the conclusion that with the bigger logo die, that I just can't get it hot enough for the oil tanned leather. So, I played around with my Wickett and Craig English Bridle Leather and I got a nice deboss by wetting the leather first, letting it return to normal color, then debossing it for the lightest touch at 280F. It's definately a fine tuning process that takes patience. I need more patience. LOL

[Northmount]

3 hours ago, lwika16 said:

I just can't get it hot enough

Let the press heat up longer so the die is definitely up to temperature.  You could wrap some insulation (that's good for 450) so it has a better chance of getting up to full temperature sooner.  You can try pressing longer, or try pressing it several times to allow the oils/waxes to do what ever in between.  Worth a test to see if it makes any difference.

[Hardrada]

6 hours ago, lwika16 said:

by wetting the leather first

Haha. That was yet another thing I was thinking of suggesting after watching a review of an electric creaser in which the reviewer warned against using the creaser on wet leather because it would burn it:

 

In that video he also explains that chrome tan requires higher temperatures to get an impression (~22:00 mark). Makes sense why one of the ways to test whether something is real leather is to apply flame: "if it burns it's not leather!" they say, but of course that applies mostly to chrome tan: I have charred veg tan with a lighter.

Again, I didn't suggest wetting the leather because I don't know whether that's a recommended practice with your machine. I don't have an electric printing machine and I wouldn't want to give advice that results in damage to the project (or worse, to the machine, or worst, to yourself! ), but if you want to experiment... wetting the leather would be something to try: try with wetting the leather, letting if dry a bit, and then stamp it; and also try applying the stamp right after wetting it. See what happens.

Edited March 1, 2021 by Hardrada

[Matt S]

 

6 hours ago, lwika16 said:

Thank you for the info Matt.

My machine goes hotter, but according to the manufactuer, it's not really good for it to go much above 450F. I just came to the conclusion that with the bigger logo die, that I just can't get it hot enough for the oil tanned leather. So, I played around with my Wickett and Craig English Bridle Leather and I got a nice deboss by wetting the leather first, letting it return to normal color, then debossing it for the lightest touch at 280F. It's definately a fine tuning process that takes patience. I need more patience. LOL

Veg tannages like bridle tend to be more susceptible to heat than chrome tannages. I /think/ that the plastic temperature is lower for veg as opposed to chrome but it's a while since I looked that up. Typically I emboss or crease veg tannages somewhere between 60 and 100 degrees C (maybe 80-212F?) and chrome around 200C. Generally I avoid applying water for debossing, as it can leave a tide mark.

3 hours ago, Northmount said:

Let the press heat up longer so the die is definitely up to temperature.  You could wrap some insulation (that's good for 450) so it has a better chance of getting up to full temperature sooner.  You can try pressing longer, or try pressing it several times to allow the oils/waxes to do what ever in between.  Worth a test to see if it makes any difference.

I'd throw a +1 at Northmount's suggestions. Remember that the plate will have a temperature gradient across it (hottest closest to the heater element, coolest at the most exposed edge), the larger the plate the larger the gradient, and that the heat controller is measuring the temperature at one specific place wherever the thermocouple is located. I tend to leave my plates to "soak" for a few minutes before first press to give it a chance to warm through.