Anyone know what these spots are on leather?

jono7183

jono7183

Active Member
Sometimes when i'm dying the leather, some spots will form, where no matter how much i put dye on, it wont get through the leather.It;s almost as if its some type of barrier. Anyone know if theres something i can do before hand, maybe treat leather or something?? I'm new to knife building and leatherwork, i'm at a loss. Thanks in advance!!002.jpg003.jpg
 
Usually that means some glue got on the leather but it could something else also.
I tend to die a half hide at a time before working. I slightly moisten the surface with water in advance so the dye is more uniform. That way if I come across any bad spots where dye doesn't take, I can cut around it.
 
Cleaning with alcohol before dyeing seems to help.....A lot of hands touch that leather before you do. I was talking to a Bentley interior tech. at a recent show who told me they had airborne contaminants in their shop that ruined several hundred square foot of upholstery leather. Turned out it was WD40 that a building maintenance guy used on their office doors.
 
There are multiple reasons why dye is rejected as though it were applied over a resist. Of course, glues and cements create their share. Bodily fluids such as spit, blood, sweat, and others---will create a resist unless washed off thoroughly. Oxalic acid will remove dirt smudges, fingerprints, etc. but will not be much help removing a resist that is organic in nature. Contact cements and rubber cements can be removed on occasion by carefully rubbing them with good quality pencil erasers. This should be done after the offending spot is DRY in order to prevent driving the wet mixture into the pores of the leather.

As in most instances, an ounce of prevention will prevent a pound of cure. Place cement only where it is needed and frugally. Do not slop it on, place it where it will not show when the article is stitched. This is a case where less is better than overkill. The seconds you expend to do the job right will save you hours of aggravation and possible loss of the article you have been unable to salvage.------------------Sandy
 
And there you have it from the Sultan of Moo



Sandy Morrissey said:
There are multiple reasons why dye is rejected as though it were applied over a resist. Of course, glues and cements create their share. Bodily fluids such as spit, blood, sweat, and others---will create a resist unless washed off thoroughly. Oxalic acid will remove dirt smudges, fingerprints, etc. but will not be much help removing a resist that is organic in nature. Contact cements and rubber cements can be removed on occasion by carefully rubbing them with good quality pencil erasers. This should be done after the offending spot is DRY in order to prevent driving the wet mixture into the pores of the leather.

As in most instances, an ounce of prevention will prevent a pound of cure. Place cement only where it is needed and frugally. Do not slop it on, place it where it will not show when the article is stitched. This is a case where less is better than overkill. The seconds you expend to do the job right will save you hours of aggravation and possible loss of the article you have been unable to salvage.------------------Sandy
Click to expand...
 
In addition to Sandy's comments often times such blotches are created during the processing of the leather at the factory. Leather is plated ie run through a series of rollers in order to smooth it and at times stiffen it. During the plating the rollers will build up spots of waxes and oils from the leathers and when the rollers are not kept clean this can be re-applied to the leather in such splotches. In this case a good cleaning of the surface prior to the final finishing stage with alcohol, acetone, oxalic acid, etc. is advisable and most pros do this as a regular process before fianl finish.
 
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