What convertible roof cleaner do you use?
Quick answer: We use a bulk trade detergent concentrate, diluted to suit the job. For cabriolet hoods we mix it slightly stronger - but not so strong that it harms rubbers or trim - and we don't publish the brand because it's only sold in bulk. For DIY, Renovo Fabric Soft Top Cleaner is a solid alternative. For specific contamination like tree sap, a dedicated tar and bug remover should tackle it first -- general hood cleaner alone won't always shift aged resin. The real "secret" is agitation: mechanical brushes and elbow grease.
There is no magic bottle of convertible roof cleaner that separates the pros from the amateurs. We buy a general-purpose trade detergent in 25-litre drums and dilute it to the job. What makes it work on a cabriolet hood is the dilution rate and the agitation, not a secret formula.
The detergent we actually use
We buy a concentrated detergent in 25-litre drums and dilute it down to the strength needed. We won't name the brand because it is a trade product, sold in bulk only. The supplier isn't hiding a Car Care Cabal secret - they just don't deal with retail customers. If you do work out what it is, please don't ring them.
It is a general-purpose detergent. The only trick is that we mix it slightly stronger for soft tops than we would for seats or carpets. Cabriolet hoods are made from a tougher synthetic fabric and take a stronger soap, but not so strong that it burns rubbers and trim.
So while our mix is a little hotter than the retail cleaners on the shelves at a motor-accessory store, it is almost certainly milder than the pre-wash a typical car wash slings over your paint -- and there are good reasons not to put a soft-top through an automated car wash at all. Those crews are known for brewing a Cillit-Bang strength Traffic Film Remover that can etch plastic and bleach carpets.
The DIY alternative: Renovo Fabric Soft Top Cleaner
In the past we used Renovo's Fabric Soft Top Cleaner. We got through a lot of Renovo's range - they are soft-top specialists and the bottles are generously sized, so the value is good. Their cleaner is probably better than the trade detergent we use now, and for a home user it is the product we would point to first.
The real "secret": agitation
Our secret to cleaning convertible roofs is no secret at all. We rely on very fit, strong young men with plenty of elbow grease.
...and mechanical brushes. There is no cleaning without agitation, and electric-powered mechanical brushes speed up the process by orders of magnitude.
Mechanical brushes only handle the large flat panels. Seams, beading and any area of exposed stitching still has to be done by hand.