To the wonderful tech support at Dyebrick: I could not be more pleased with the results. 1. Image 001 is my 42 year-old fireplace after 10 hours of scrubbing with a baking soda/dish detergent paste and every other product I could find. 2. Image 002 shows the fireplace after applications of a sample size bottle of Rustic Brown Dyebrick with the fixative agent. Beautiful! 3. As we discussed, the only problem was that, after drying, a brown powdery residue rubbed off on my finger. 4. With the help of technical support at Dyebrick, we surmised the fireplace interior was made of fire bricks. Fire bricks have an aluminum oxide content that can be as high as 50-80% with correspondingly less silica. 5. Technical support at Dyebrick recommended painting with a highly dilute solution of Seal-Krete which I ordered at Home Depot in the US : 8-1 dilution worked for me. 6. Image 003 shows the fireplace after Dyebrick plus Seal-Krete. It looks like beautiful antique brick and matches my marbleized fireplace surround. 7. Image 004 shows my beautiful “new” fireplace with new gas logs illuminating the lovely interior. A big thank you to all of you at Dyebrick. I was quite taken aback when I realized that I would have to order this product from England! To anyone in the US, do not hesitate. The product arrived faster than expected. The functionality is unmatched and the technical support is super resourceful and fast, even with the time difference! I could not more highly recommend Dyebrick. This could be my greatest accomplishment of the year. Karen Hyman Cherry Hill, NJ