When to oil?

[mcguyver42]

Hello, I've been at leathercraft for a few years now, but I don't have a lot of hands on unfortunately.  I'm really struggling with being able to evaluate leather for proper suppleness/ oil content?  I am making a briefcase for my son.  I selected a 6-7 oz veg tan side from my leather collection.  It's a Tandy hide, probably Brazilian grade C, not terrible looking, not been oiled since I have had it.  I rolled it out on my bench and had to weight both ends to hold it down while cutting out my pieces.  My scratch awl didn't make a very convincing groove or line to follow; it was very shallow, almost like a light cat scratch and I had to look at it from different angles to see my cut lines.  I had to make 4 or 5 passes with a reasonably sharp round knife.  My knife would get stuck, and I had a few skip offs.  I ended up pulling it towards me, and even using it like a strap cutter.   My big pieces were still wanting to curl up by an inch or more, even after laying out on the bench for a few days.   I had a disaster of a dye up and pretty sure now that I should have oiled my leather.   I'm wondering if some of the above should have been clues that this hide needed oil?  What do you guys look for when you are evaluating a hide for it's overall condition and usability?  Do you have some tests that you make on the leather, or do you just know by feel and sight?  How does temper figure in there?  Is firm temper leather just dryer leather?  Thanks in advance,  Guy

[fredk]

It does sound a bit like your leather is too dry and hard. Does it feel and act like cardboard? A good sharp knife should slice through the leather easily; not like a  'hot knife thru butter' but easily with a little bit of effort. A scratch awl should almost cut the surface

Mix some, very little, NFO with hot water and a few dribbles of washing up liquid soap. Then apply some of that in big swathes across the leather using a sponge. Not too much, too much NFO is bad. Allow that to soak though for 24 hours, see how the leather feels after that. If it still feels stiff and hard apply again, allow it to work for 24 hours and repeat until the leather is almost pliable, Stop then and allow the leather to rest and the NFO to work for a few more days

Assessing the temper of leather does come with experience. I once got stiff as a board leather from Tandy. I managed to get a discount as it was like a sheet of masonite/hardboard but I knew I could oil it and rejuvenate it. Firm temper is often a measure of how the leather was tanned. I have belly leather that is as floppy as cloth and some which is as stiff as thick cardboard, neither is too dry

[mcguyver42]

It seemed like the leather was reasonably pliable.  I just rolled out the rest of the hide on the bench for a look at it.  Possibly it may feel a little light for the size but I'm not sure.  What does the soap do?  I gave it a very heavy oiling with olive oil a few hours after the dye up.  The next morning I gave it another very heavy oiling, and then two more heavy oilings.  It didn't soak the oil up near as fast on the last oiling or two, and I was able to rub it in circles and even out the blotchy dye job some.  Still it came out much darker than the intended light brown, and the pieces are curled.  I didn't mention this before because the curling was already very evident, and I didn't want to add variables that may not apply.  There were some spots on the leather from the workshop.  I tried 3 of the methods that are well agreed upon by members here.  (Alcohol, 50/50 lemon juice and water, oxalic acid)

 

 

[mcguyver42]

[mcguyver42]

[mcguyver42]

[mcguyver42]

The first backside picture is of the really curled up piece.  The other 2 backside pictures and the 2 grain side pictures are from the side that the pieces were cut from.  I really appreciate your input.  I think the project is a flop at this point.  I'll go ahead and build it for the practice, but I shure would like to learn from this.  Thanks

Edited May 10, 2023 by mcguyver42
misspell causing unclear meaning

[chuck123wapati]

what you will learn is that leather will form to whatever shape you make it form to, by the time your done making your briefcase it will be flat and not a flop. Just keep going. 

[dikman]

Could be a feature, to ensure it doesn't go floppy when made?

As Chuck said, keep going, at the very least it's all experience. Working with leather is a bit like shooting black powder, there's an element of unpredictability involved.

[Burkhardt]

The soap will act as a lubricant slightly. By handling and making what you are will loosen it up and make it pliable and the oil will work in deeper. Eventually you'll have to add a conditioner to make it last but the more you work it the better it will get. Just do it in baby steps don't force it. Another reason not to dye it first is that it will make it stiffer. You can take about any leather that lays flat and dye it and it will curl up and become stiff.

[mcguyver42]

FredK also mentioned putting a little hot water in the mix.  So if I put say a pint of oil in a pot, how much soap and water?  and we are discussing regular dish washing liquid here?  I feel that I've oiled this leather enough, and that any more would be too much.  Actually it's becoming tan on the back side, and I hope I don't run into any glue stick issues.  Still, I wish there was some kind of test, (A moisture meter on wood for example).  I  compared my dyed and oiled pieces to the untreated portion of the side to try to discern some differences that I could call "tests":  examining the cellular structure of the edges with a magnifying glass, trying to note different sounds when rubbing the back side with my fingers and fingernails.  I couldn't pinpoint any notable differences. The grain does appear to be thinner and more defined on the oiled pieces, but that could just be the dye.  I think the expected weight when you pick up similar sized pieces is a little different.  The oiled pieces do make more of a satisfying smack sound when I drop them onto the workbench.  A thumbnail impression is definitely more self healing on the non oiled pieces.  I know that I'm over analyzing, and should just let experience take it's course, but I bought quite a lot of leather in the beginning.  It wasn't top quality to begin with and it's been in storage for 3-4 years.  I'm concerned with losing the whole lot of it if I don't learn how to take care of it.  When I say storage, I mean in the house under heat and air and out of the light.  I'll try all of your suggestions, definitely oil with soap before I cut out and dye the rest of the pieces.  At least it reassuring to know the curling is normal,  I appreciate the experience and encouragement.      

[mcguyver42]

If I understand Burkhardt, are you saying that you oil leather that is already in good condition before dyeing as a sort of damage control, and then again after?  Mine was dry to start with.  It sucked the dye right out of the sheep's wool as soon as it touched, I couldn't control it.  I used so much light brown dye that it ended up chocolate.  But going back to that water thing, I didn't know how much soap to use and didn't want to overdo it, so I just cased it real good with water.  You and Chuck both said that the surface tension would be reIeased during normal handling over the course of the build.  But,  I worked it through folding the edges back gently, and not being overly forceful as you said.  I cupped my hand over the interior portions and used my fingers to push up some from the bottom.  I could see a pull up effect on the leather when I was doing that and could feel the leather relaxing.  lo and behold, it lays nice and flat.  I let it dry overnight with a cutting board laying on top of it for good measure.  The picture is from the next morning.  Problem solved!   I'm looking forward to finding a recipe for the oil, dye and water if anyone has one.

[mcguyver42]

Update for what it's worth.  I'm a beginner so verify anything that I say.  For me,  I think I found my test to see if my veg tan leather needs to be oiled  Find a waste spot on the leather and scratch a  short line.  It should emboss a line instead of just scratching through the top of the grain.  oil if needed without being too heavy handed as Fredk cautions, wait the requisite 24 hours and retest.  I did that on the side under discussion, and my knife slices right through in one light to medium effort pass with maybe a fiber or two hanging on. 

[dikman]

Good stuff! But the reason it finally worked is because the cat put in an appearance. Everyone knows that cats are magical/mystical creatures.

[Burkhardt]

12 hours ago, mcguyver42 said:

If I understand Burkhardt, are you saying that you oil leather that is already in good condition before dyeing as a sort of damage control, and then again after?  Mine was dry to start with.  It sucked the dye right out of the sheep's wool as soon as it touched, I couldn't control it.  I used so much light brown dye that it ended up chocolate.  But going back to that water thing, I didn't know how much soap to use and didn't want to overdo it, so I just cased it real good with water.  You and Chuck both said that the surface tension would be reIeased during normal handling over the course of the build.  But,  I worked it through folding the edges back gently, and not being overly forceful as you said.  I cupped my hand over the interior portions and used my fingers to push up some from the bottom.  I could see a pull up effect on the leather when I was doing that and could feel the leather relaxing.  lo and behold, it lays nice and flat.  I let it dry overnight with a cutting board laying on top of it for good measure.  The picture is from the next morning.  Problem solved!   I'm looking forward to finding a recipe for the oil, dye and water if anyone has one.

Veg tanned is a raw unfinished leather so some people add a little soap in the water for stamping and also carving, the soap works as a lubricant. Yes, oil the leather before you dye it so the alcohol in the dye doesn't make it stiffer and the dye will absorb more evenly. Any veg tanned leather should be oiled at some point to prevent cracking and falling apart.  

[mcguyver42]

I gotta try to design some gusset's now, I better up the cat treats

[Northmount]

@mcguyver42

I'm a little late to this discussion. 

If your leather curls too much for your comfort when laying out and cutting, moisten the leather enough that it doesn't curl.  Lay it out so the curl is facing down.  You might need to place something on top to help flatten.  Let it dry flat.  Leather will tend to curl while drying.  Be careful what is against the grain side of the leather as it may transfer a pattern to the leather.  Even paper towel will leave a pattern, so your surface needs to be really smooth.

I use a pencil or pen to lay out my cutting lines.  Make sure the lines are not going to be seen in the finished product.

Moistening or oiling before applying dye helps to get a more even coat of dye.  To me, it is better to have the dye absorbed more slowly so you don't have dark patches where your sponge or sheep wool touched down.  Then it is much easier to get a more even dye job.  It may take a couple additional dye applications to get it completely even.  If you want the finished dye job to be light, dilute it a lot first.  Each time you add dye, the leather gets darker.  Hard to make it lighter when it's already too dark. It is also wise to dye all pieces (of the same batch of leather) at the same time to reduce the variance between parts when assembled.

I like to dip dye.  But it is hard to get a light dye job when doing that.

Another option for applying dye is to use an air brush.  There are cheap ones around that do adequately for applying dye to a large area, not trying to do fine detail like some fellows do.  My skills are just for broad coverage.  Don't have the coordination for detail.

Make sure your cutting blade is really sharp.  The angle of the blade edge needs to be quite shallow so it doesn't act like a thick wedge.  It's not like cutting meat where the meat is soft and deforms easily letting the knife through.  There are lots of posts about sharpening knives.  Pay attention to "scary sharp"!

[mcguyver42]

Sounds like diluted dye applied with an airbrush might be thriftier too.  At $25 - $30 a quart this stuff gets pricey in a hurry.   And not all bottles are full by the way, some up to the cap, and some 1 1/2" down the neck.  We are talking fluid oz. here, so I don't know?  I've seen powdered dyes offered by some suppliers that you mix up with denatured alcohol.  Denatured alcohol is out of control now though, mostly methyl alcohol, and who knows what else.  Woodworkers don't want to use it in their shellac anymore, and are resorting to Everclear if they can get it.  The same applies to us.  Between that and the alcohol drying out the leather, it's making me want to take a hard look at water based dyes.  Or other ways to dye leather?  Any input on that?