TheSamba.com :: View topic - Best Chemical Prep/Cleaner prior to Bedliner?

Thu Jan 05, 2012 10:23 am

Hey folks,
I'm getting real close to the application stage of my bedliner project. For the past few weeks I've been taping, sanding, etc. when time and shop temperature allows.
I'm doing the GW style around the bottom like numerous others and I have a couple quick questions:

-What is the best chemical to clean and prepare the surface prior to application of the bedliner? I've read about several different options like acetone, lacquer thinner, xylol, "wax and grease remover", etc. I was anxious to start sanding and didn't clean the surface before so now plan to clean it after to remove any dust or contaminants. Hope that will still work out ok. Looking here: http://www.youtube.com/watch?v=Q1l8HjMva-c he cleans with xylol then sands, other sources suggest acetone or thinner while others say "wax and grease remover". I've been to an auto paint shop and FLAPS without much luck for "wax and grease remover". Is that just a term for auto lacquer thinner or acetone? Basically I just want to remove any remaining wax, grease, sanding dust, etc. without leaving any chemical residue that may contaminate the bedliner product.

-I have also smoothed out a couple spots with body filler so would the best method be to sand those nice and smooth then shoot them with primer, then sand again to slightly rough it up prior to applying the bedliner? Would a filler primer or self etching primer be better? Overall the factory paint was still in good shape so it's not really down to bare metal. Would one of the chemical cleaner/preps mentioned above affect or contaminate the cured body filler if I tried to clean them or clean around them before applying the primer? Should I just prime it after sanding, without a chemical cleaner/prep, then clean everything including the primed areas prior to applying bedliner? If so what product?

Hope all this makes sense, basically I'm at a point that I just need a little guidance/reassurance on how to proceed to avoid making major errors. :)

Thanks!

Thu Jan 05, 2012 12:23 pm

I'm no expert but have recently gone down the "painting the van" process... but haven't (yet) done the bedliner. I do have a couple of thoughts based on my research.

Herr Motorspiele wrote: -What is the best chemical to clean and prepare the surface prior to application of the bedliner?

Some kind of product called "PRE" might be added into your research. Its supposed to be a pretty good wax/grease remover. When I painted my van all I did was sand, effectively wet wipe it down with water, followed by using a tack rag to remove all the dust. Again, I'm sure you could use a bunch of exotic products but this is what the auto paint professional suggested. YMMV.

Herr Motorspiele wrote:
-I have also smoothed out a couple spots with body filler so would the best method be to sand those nice and smooth then shoot them with primer, then sand again to slightly rough it up prior to applying the bedliner?
The primer will need at least a little "tooth" to grab so not too smooth. I'd hit it with some 150-320 range paper. Remember that the bed liner is going to be a rough surface so you aren't striving for a mirror finish on the underlying surface.
Also, the filler you use is important. Conventional "bondo-type" stuff can trap moisture so be sure that it is well entombed on both sides within the paint product. Personally I used a full metal bondo ("All Metal"???) that claims to be water proof. It was at least 3x the cost but seemed far better. Just something to keep in mind.

Herr Motorspiele wrote:
Would a filler primer or self etching primer be better? Overall the factory paint was still in good shape so it's not really down to bare metal.

My head was also spinning trying to figure out a primer but I am pretty sure in saying that if its not down to bare metal you don't use a self-etching.

Herr Motorspiele wrote: Should I just prime it after sanding, without a chemical cleaner/prep, then clean everything including the primed areas prior to applying bedliner?
Thanks!
Yeah I believe that's the idea. The epoxy primer that I used, for example, said to top coat with 7 days. Applying another paint product within this time allows the still-soft primer to chemically bond to the topcoating paint.
I'd verify this by reading the label of whatever bed liner product you are going with.

Again, I'm not a pro but so far my paint hasn't fallen off my van (after 2 weeks of sitting in the garage! :lol: )

Thu Jan 05, 2012 8:05 pm

Hi,

The common standard for a cleaner prior to paint is lacquer thinner. Lacquer will remove all wax/grease. Just sand it really well, and use lacquer thinner and a tack cloth prior to paint.

After sanding, I like to lightly scuff with scotch brite (the red scotch pad) and lacquer. I then clean with lacquer on a rag, and then use the tack cloth. As long as you clean, clean, clean, and tack, you shouldn't have any problems.

Good luck!

Scott

Thu Jan 05, 2012 10:00 pm

I used lots of PPG wax & grease remover...don't use that crap duplicolor brand.

or what was mentioned above.

search for my bedliner thread.

Thu Jan 05, 2012 10:41 pm

Thanks for all the replies. I have H.E.T. 1501 premium wash thinner from these guys: http://www.growautomotive.com/
Picked it up from the pro auto paint shop so it must be good stuff $$!
Guess I'll use that to clean up after sanding on the main areas.

Still not clear though if I can use that to wipe down the cured body filler spots before primer is applied? Will lacquer thinner negatively affect the filler? Should I just use a tack rag on those spots?

After reading up on the bed liner it said it could be applied over bare metal or unpainted surfaces and has a note about freshly painted surfaces (may not stick well, test an inconspicuous area, etc.) I'm assuming that they mean paint not primer right? Should I even prime the areas I've used filler on? I definitely see the logic in "entombing" the filler with primer as zippyslug31 mentions above. On the other hand, simply scuffing/sanding everything then cleaning it up before applying the bedliner would eliminate a couple steps and quite a bit of extra work! Thoughts?

One more question, does everybody remove their tape and replace after sanding?! :)

Thu Jan 05, 2012 11:55 pm

Use Dupont 3812 fast drying enamel reducer to clean up the sanded top coat,prior to priming , prior to top coating.
It's a fast drying non-aggresive thinner, that won't attack the base coat of the paint you just have sanded.
Lacquer thinner is to hot & will make a mess out of the base coat under the clear you just sanded.

Big no-no.

PPG wax & grease remover s not much more than a fast drying mineral spriits.
I have used mineral sprits to degrease & prep paint--it works well ,and is harmless to whatever you have on the body after sanding.

Stay away from lacquer thinner on a sanded surface.
Not good.

Fri Jan 06, 2012 4:17 am

I agree with Terry-I've wiped with Laquer thinners to clean prior to paint and had a lot of "fish-eyes" as a result :cry:

Fri Jan 06, 2012 7:56 am

What bedliner product are you using? Read the instructions carefully, they will most likely tell you exactly what to use. I used Hurculiner and they specified Xylol as the required cleaning agent after sanding. This may be different depending on the product, bedliner is not paint.

Fri Jan 06, 2012 7:59 am

Terry Kay wrote: Use Dupont 3812 fast drying enamel reducer to clean up the sanded top coat,prior to priming , prior to top coating.
It's a fast drying non-aggresive thinner, that won't attack the base coat of the paint you just have sanded.
Lacquer thinner is to hot & will make a mess out of the base coat under the clear you just sanded.

Big no-no.

PPG wax & grease remover s not much more than a fast drying mineral spriits.
I have used mineral sprits to degrease & prep paint--it works well ,and is harmless to whatever you have on the body after sanding.

Stay away from lacquer thinner on a sanded surface.
Not good.

3812 is awesome.
Getting harder to find here in NY with new laws.

Fri Jan 06, 2012 10:07 am

Interesting! Ive never had any issues with lacquer thinner prior to painting and I know quite a few professional painters who use lacquer for prep prior to paint. It wont cause fisheyes, but it could cause softening of the paint or clear if it isn't fully cured.

Correct me if im wrong but Ive never had a problem.

Scott

Fri Jan 06, 2012 10:59 am

Been painting semi's since 1979 for a living.
Painted cars prior to that.

3812 is the prep & wipe down of choice simply because it won't and will not solvent wash the primer, or paint that your top coating over and is an excellent grease remover.

Try wiping down a lacquer based primer ( SW Ultra Fill is the best) prior to painting.

You'll have a lacquer rag full of primer.
Same with any base coat, as it's a lacquer based pre finish.

3812 is the safest bet, and you'll only need it to do every painted / non-painted surface prior to priming or top coating.
Dupont's Prep-Sol is another good product for wiping down a vehicle prior to painting, or top coating.

Mineral Spirits works good too.

What your looking for is the "Best" universal surface prep --one size fits all product.
The two or three I've mentioned are all of that.