I am currently doing some rust repair on my 1985 Chevy M1028 CUCV pickup. Part of the repair is to convert or neutralize the existing rust. This is done in an effort to keep the rust from coming back and ruining the topcoat. This product is available in a spray or a liquid to brush on. I am reviewing the liquid since I have found that it works better than the spray. The 8oz bottle was purchased from AutoZone for around $5.00 Here is the good and the bad.
Easy to use – To apply you sand down the rust, clean the area, and then brush on the Extend. Two coats if you are going to topcoat three if you are not. 20 minutes between coats and 24 hour dry time. I just use an acid brush to apply.
It works – this product neutralizes the rust so that it does not come back. I have used this product for many years and I have equipment I have used this on that is still rust free after many years. The rust will turn purple after it has been converted.
Price – A little of this product goes a long way so the 5 dollar 8oz bottle will last.
Consumables – I would not recommend cleaning and reusing brushes and containers after they have been used with Extend. You want to use a new container every time you use this product because you to not want to contaminate/activate the new stuff in the bottle. So you will go through a few brushes or containers using this product.
Finish – Once the product dries it is not a smooth finish and they do not recommend sanding the surface since it will break the protective barrier. Top coating the Extend with primer and paint will show a dark spot or brush marks where the Extend has been used in many cases.
In conclusion I recommend using this product to help avoid rust coming back. But keep in mind what I mentioned above about the finish.
Rust on bumper before the extend
After the first coat of extend has dried
24 hours after the second coat has dried