Stripping Glassfibre
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I have found a stripping agent that, in my experience, is safe on GRP. It's called "3M Safest Stripper," and you can buy it at K-Mart. It's non-volatile and doesn't generate any toxic fumes. Additionally, it won't irritate skin with a short-term contact. The stuff to avoid regardless is methylene chloride, and most paint strippers (Strip-Eze, BIX, etc.) contain this. I have stripped my Europa using three techniques on different parts: sanding (some of it with a power disc, some by hand), scraping (using Red Devil paint scrapers), and stripping with the 3M stuff. All three techniques have good and bad points:
Sanding
Pros:
- No worries about stripping chemicals attacking gelcoat.
- Removal of only the components you want.
Cons:
- Takes forever (obsessive/compulsive types may consider this a pro, i.e., the sign of a "true believer").
- Sandpaper fills rapidly, unless you wet sand, and then you can't use anything finer than 220.
- Leaves scratches, particularly if you use a power tool.
- Impossible to thoroughly strip nooks and crannies like those found around door openings.
- Has the potential to alter the surface shape.
- Makes tons of dust.
Scraping
Pros:
- Makes less dust.
- Faster on flat or gently curved surfaces than sanding.
- Removal (mostly) of desired stuff, pretty easy not to gouge gelcoat.
Cons:
- Stripper blades dull fast, lots of sharpening (keep a file with you).
- Sound drives me crazy, much like fingernails on blackboard - wear hearing protectors
- Impossible to strip tighter features.
Stripping
Pros:
- Less elbow grease required
- Tight spots can be stripped easily.
- Factory primer/surface, where present, can be left on if so desired.
Cons:
- Messy.
- Stripper really needs to be left on overnight.
- Cleanup after stripping must be very thorough.
I prefer using the 3M stripper. Although I have yet to apply a topcoat to my car, there are several panels that have been primed and sanded (with Featherfill) and have survived for more than two years with no evidence of underlying defects showing through.
Technique:
- Apply and wash off the stripper per instructions. It really DOES have to be thick to work.
- Make additional applications as required. The stuff is not heavily caustic, and, depending on how much paint is on your car, it may take a second or third pass.
- After a thorough washing with water, use acetone and steel wool to complete the stripping process. This has the advantage of washing off any remaining stripper or other contaminants while continuing to remove undesired paint/primer residue.
- Leave the car for several weeks in a dry place, just to be sure. Prior to applying anything to the surface, scuff thoroughly with 220 and wash with acetone. You may then safely apply filler or primer. My primer/surfacer of choice is a product called Duratec, a polyester primer/surfacer that is vastly superior to Featherfill.
Regardless of the technique you use to remove old paint, you WILL have lots of priming and blocking to do if you want a good surface. My plan is to use the Duratec for surface build, then apply a final coat of an epoxy-based primer/sealer, which should help prevent any contaminants that might remain from affecting the topcoat.