How long should I wait for primers and fillers to fully cure and be done shrinking? I have been painting some projects and parts, and it has actually worked out well. But I have done a few panels that ended up showing major sand scratch swelling and orange peel, etc. If i'm just letting my cheapo build primer and sealers air dry, should I let the car sit a few days? A few weeks? Also, it seems i should do final blocking after proper shrink (full cure) time, right? Thanks for any help!
It is really going to vary from product to product and temp. Plewase add a few specifics of what you are using (laquer , urethane , etc) and the temp of your shop. Some products can really have a lot of shrinkage such as laquer, and others such as acrylic urethanes and epoxys seem to have less.
if your getting sanding scratches coming thru, you need to finish your bodywork with a finer grit paper, usually 220. orange peel can be from not sanding the primer smooth enough, using to low air pressure while spraying either your primer, sealer or paint. any build primer should not shrink if cured long enough, and catalyized correctly. some sealers require topcoat within a certain time from when you spray it, read the label. any time your applying material and you have to let it air dry, don't "lay" the material on to heavy because it'll take forever to dry. always read the label and reduce and activate your material exactly how it say's on the can!
I've been using cheapo lacquer primers to build with. I usually shoot epoxy over bare or filler, then build and sand with the lacquer. I got the sand scratches in some fenders after doing the same process (same primer, same sandpaper grits) on the hood that turned out beautiful. But as I think back, I let the hood sit in final primer coat for a couple of days before I finished sanding. Also, my temps were around 80 deg. and very low humidity. I probably ought to give the primer layers some time to cure? Maybe also stop using lacquer primer?
lacquer will always move its non catalysed just thinner and primer. 2 part is the only way to go. try some upol 2 k primer its a dtm that means direct to metal it can made to be a filler, surfacer and sealer all in one. great stuff . billy
Yeah always use a high build primer that has a catalyzed hardener. I know it's more money but it's definitely worth it.You can fill in 80 grit scratches with it. Saves alot of time.I've read articles where the old time pros used to leave lacquer primer sit for sometimes up to six months.It's just not worth going through all that bodywork prep and have it be ruined when scratches start appearing 6- 12 months later.
Take all your body filler to 220 grit that will stop the shrinkage from showing up later and dont shortcut, go 80, then 120 then 150 and finally 220. Then prime it
very good advice, at the least finish your body filler in 180. And it is a must to use a good 2K primer.
Yep...As a body man of 8 years, I've learned that if you don't have those deep sand scratches for the primer to shrink down into, then you wont have any sand scratch swelling in your panels. Paint manufactures recommend (for the most part) jumping grits by no more the 100. So I have always gone 80-180, then 240...and that has worked great for me. I do this crap for a living.
Not to Hijack, but has anyone used that slicksand for multiple years?? Wondering how its help up. I've used it on a few cars, and it does work pretty good.
I have used polyester primer with great results for quite a while, Evercoat slick sand, or they have another one that works good also, I have used with really good results, is Standox Polyester primer, but it is a lot more $$, I usually do the poly a couple times then do one time of urethane catylized primer, to finish out to wet sand, not supposed to get the poly wet!! I know a few guys that love the PCL poly...but throw away laquer primer, its not worth the can its put in..
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