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1 When is there a need for an Adhesion Coat in leather auto color refinishing?
2 leatherBond3D™, leatherBond7A™, leatherBond8C™ or leatherBond9D™ ,what’s the difference in the products?
3 leatherFill90™ - in what situation is this product used?
4 Impregnator26™ - This is used to tighten up exposed grain and corrium, correct?
5 Skin4™ - What is this and when is it used?
6 Duller63™ - If I am using the matte semiTop56M do I still need this product?
adhesion73™ is an aqueous compact resin developed as an adhesion promoter to improve adhesion for further color or top coat refinishing.
It is recommended to be used on semi-aniline leathers where degreasing has been done during prep cleaning especially to headrest and armrest.
It is highly recommended on suspected tough leather finishes especially auto, motorcycle and sports leathers where crosslinkers has been used.
Also mandatory to used especially on aniline leathers after oilEffect2.8™ or waxEffect9.9™ pull-up effect replenishing prior to top coating.
When adhesion scotch tape test fail, incorporating 1 to 3% crosslinker25™ will significantly boost key performance.
Crosslinker creates a tougher film and also ties up some of the hydrophilic elements.
The main concern about color refinishing is delaminating or peeling or poor bonding with the old surface especially on non-absorbent auto, motorcycle or sports leathers.
Below are situations where applications are recommended:
1. Inadequate Prep Cleaning:
This is especially true where the leather has unknown foreign non-stick contamination and inadequate prep cleaning.
This non-stick condition do not provide bites for the new coating, thus fine sanding without physical damages to the grain is vital.
Adhesion coating helps open-up, pile or anchor itself into existing old coating and prepares as a sticky base for subsequent coating.
2. Tough Cross-Linked Finishing.
This is usually associated with auto, motorcycle and sports leather where crosslinkers has been used.
This type of crosslinked finishes is so tough that additional new coating fail to stick for long.
Unless they are chemically non-destructive prep cleaned and fine sanded.
And additional crosslinkers added to the adhesion coat, adhesion may still fail after a scotch tape test.
3. Chemical Bond Damages by Solvent Prep Cleaning:
Indiscriminate solvent prep cleaning can damage the chemistry bond of the old leather finish.
Unless it is a 100% total removal of old finish, which is laborious and not very necessary.
Too much solvent wash out the fatliquor from the leather structure, thus finishes feels stiffer than before.
This unintended fatliquor removal has more tendency for new finish to creak sooner where the leather structure shrink without refatliquoring.
This unnecessary solvent related weakening of the old finish need an adhesion-in-between-coating to help for proper adhesion.
Adhesion Coat also known as Sealer Coat is an intermediate application to improve adhesion within a refinishing system.
General refinishing system comprise of:
Dye-Staining > Impregnation > Adhesion-Coat > Color-Coat > Top-Coat > Feel-Coat
Further question are welcome
Roger Koh
leatherBond3D™, leatherBond9D™, leatherBond8C™ or leatherBond7A™.
The 3D and 9D are aqueous polyurethane based leather bonding compound.
Advantages over solvent based polyurethane leather glue are without the “special shipping requirements and potential health problems”.
Moreover, aqueous bond is user friendly, solvent based glue is not and it has to be precise in application as it will lift color coat which leads to unnecessary color repair.
Otherwise, excess solvent glue only removal is by careful sanding.
Comparatively excess with aqueous bond can be wiped off safely without color or top coating damages.
Controlled excess repair with 3D, 9D & 8C can be further improved or smoothen out efficiently and safely with 7A.
Aniline dyes can be added to the 3D, 9D & 8C as a two-in-one repair depending on situation.
3D is for heavy structure repairs where a sub-patch is required for strength.
9D is for light surface repairs like flaps and abrasion where softness is much appreciated.
8C is an aqueous acrylic leather bond especially for absorbent leathers where darkening is not desired.
It’s the middle road to take where both 3D & 9D produces undesirable darkening effect on pastel absorbent leathers.
7A is a nitrocellulose lacquer emulsion use as a bonding aid for 3D, 9D and 8C to remove excess.
It’s developed to soften and smoothen repairs without resorting to sanding.
Further questions are welcome
Roger Koh
leatherFill90™ is a tannery leather stucco that fills leather repair that saves the leather for sale.
Aftermarket filling repair is often after bonding repairs for aesthetic reasons.
It is seldom necessary to be used on fine leather (0.4mm) garment repairs as natural scar are acceptable with bonding repairs.
It is commonly used on more firm and heavier upholstery leather (0.9 to 1.5 mm) repairs as a leveler for aesthetic reason rather than strength.
Comparing with other instant heat cured compound, leatherFill90™ requires an 8 hours natural curing time.
But the result will be soft as leather, sand-able more permanent with less chances of cracking.
Heat cured compound repair either with blow heat or heat iron is a risky undertaking as using heat will likely cause shrinkage to the leather.
If time is a factor, alternative warm air speed up drying time during before and after application on successive build up coating could be compromised for best result.
Matching colors can be mixed for the final layers with subsequent aniline mixed impregnator26™ for a smoother appearance before color coating.
Further questions or comments are welcome.
Roger Koh
All leather upholstery is made for one reason, to be seated on.
Dry and wet rubs with the full body weight.
And often times heavy denim jeans with metal studs are so damaging to leathers.
Very soon the colors wear out and the crust left exposed.
Ever wonder why once the pigmented color coat is worn off.
The crust is not as strong as the delicate absorbent full-grain aniline leathers.
Yes, the strength of the leather is at the grain layer.
In pigmented leathers the top grains are often corrected, buffed and or embossed.
Just like the biblical Samson & Delilah when he lost his hair he lost his strength.
When the leather grain is removed for what ever reason, the strength is lost.
Worst when a corium split is used and end up as pigmented leather.
The corium is the layer below the grain; the fiber is more porous and coarse, thus weaker.
This is where the impregnator26™ comes in play.
It’s an aqueous protein compact resin blend compound formulation.
It’s especially developed for exposed worn grain and corium crust.
It has good filling and leveling properties.
It is film forming to restore worn areas to level out uneven penetration.
Including sealing surface cracks for improve abrasion resistance.
Further questions or comments are welcome.
Roger Koh.
Roger,
What is skin4? When is it used?
skin4™ is 0.4mm thick vegetable tanned lambskin used as a sub patch or as a surface skin repair.
This full grain leather is thin and strong, for beauty and strength of repair.
Used as a sub patch so that the very thin edge of this sub patch don’t really show through compared to a thicker piece.
It is always trimmed to flow with the contour of the damage, the wider the stronger the hold depending on desired strength.
It’s always bond suede to suede on the lower overlapping edge first that holds firm before bonding the upper edge.
Another use is to be bonded on top of a leatherFill90™ / stucco repair where part of damaged leather is missing, example dog chewed damages.
Trimming this thin skin over the repair leaves only the edges to be taken care of.
This grafting type repair is more reliable and homogenous to be more authentic in nature.
As skin / leather have natural moisture content, it is always compatible to work with an aqueous leather bond.
Solvent glue somehow delaminates as the aqueous bond homogenize with the leather on the long run.
Roger Koh.
For aesthetic and strength semiTop56M™ matte is a compromise.
Commonly, gloss is usually strongest, satin comes next and matte is usually weakest in strength comparison.
duller63™ can be used on color coat too with the same inherent characteristic.
Add dullness for appearance only, call aesthetic?
Aesthetic needs strength too for physical performance.
As I said leather upholstery are all designed to be sat on.
It need a touch of both appearance and brute strength like the “Beauty and the Beast”.
Roger Koh