(Which) Stain & Heat ?

[DonLeister]

Gun stock makers like to use a version of this stain, iron nitrate or ferric nitrate. It looks like it gives a redder color than straight nitric.

 

[dan gall]

This paper seems germane:

 

https://www.tandfonline.com/doi/abs/10.1080/00218468208073207

Based on the below I wouldn't want to use this if I couldn't keep it to an even, predictable skin effect.  I'd want to scrape a different area of the sample every 3-6 months to determine what, if any propagation rate there may be into the wood after treatment.  If there is post-treatment propagation I'd want to know how long and how deep into the wood it propagates.

"Infrared and ultra-violet spectroscopic analysis of nitric acid treated sugar maple and isolated wood polymers indicated extensive oxidation, nitration and hydrolysis of the wood polysaccharides and lignin. The major effects were noted at ambient temperature although additional treatment at 100°C caused further modification. The lignin and xylan (hemicellulose) were the most extensively modified components as monitored by Klason lignin, Kjeldahl nitrogen and sugar analyses. Lignin is heavily nitrated and over 30% of the xylan (xylose) is lost during nitric acid treatment. The major degradation product isolated from nitric acid treated maple was 2, 4-dinitroguaiacol. These findings suggest that oxidation, nitration and hydrolysis of wood polymers are important aspects of nitric acid activation of wood surfaces."

[Will Turner]

While not an advocate, what may help is to treat the acid post application and heating with heat gun is an application of alkaline nature.   Potassium Silicate to seal and restore some stiffness.   In the past the concern was potassium silicate could degrade the wood.   Perhaps the acid alkaline balance might be achieved?

 

[Wood Butcher]

21 hours ago, Spelman said:

Tf?

Ikr?

[uguntde]

I can't say what the original Instragram post meant to show. But I have a good idea what nitric acid does. It nitrates benzene rings, for example in proteins with aromatic residues. This is called xanthoproteic reaction. As lignin is a polymer with lots of benzene rings they will get nitrated and change colour. The outcome is often a dirty pink which is not the colour you want. The heat just accelerates the reaction.