Hi Mark
As always it is good practice not to overwet into the carpet. It is possble that solution can seep down into the joins of the tiles and cause a wicking of the bitumen backing material (if they are bitumen backed). This would be more likely to ocurr if you were to allow stronger alkalinity products or solvent formulated pre-sprays to penetrate as this could break down the bitumen ready to wick up over several days on drying.
Sometimes on heavily trafficked low profile loop carpets they might appear to clean up very well, but on drying you can get a wick back of deep seated soil or possible loosened bitumen from the backing. This is where bonnet cleaning may have an advantage over hot water extraction. Although (in my opinion)it may not be such a deep clean, it could be considered a safer option which can also produce very pleasing results to the customer .
Sometimes these low profile tiles tend to hug the uneven contours of the sub floor and you can tend to lose vacuum power in the retrieval of solution which can leave certain areas wetter than they should be.
Also take care when using any solvent spotters on gum, tar or oil based stains due to the potential solvent breaking down the bitumen and wicking to stain the surface fibres.
I prefer the use of citrus gels in these situations but still take great care in not allowing the product to remain in the fibres to cause any subsequent wicking.
Hope that helps, and good luck with the clean.
Regards
Robert Olifent
