Author Topic: Beginner to paint  (Read 5491 times)

0 Members and 1 Guest are viewing this topic.

Offline Motoguy23

  • Enthusiast
  • **
  • Posts: 208
Beginner to paint
« on: October 03, 2012, 03:39:09 PM »
Well I've made the decision to learn how to paint a motorcycle.  I have the guns, compressor, sanding equipment ect...  I've bought and read some books and while they show technique and tips, they never explain about the paint itself.

There's urethane, lacquer, epoxy paints, sealers and intercoats of clears.  There's hardeners, thinners, retarders and more.  Its confusing to a guy like me.  Can anyone at least point me in the right direction because this is the last thing before I try  spraying the stuff and doing hands on learning.

And if this topic isn't supposed to be in this part of the forum I'm sorry.
All glory to the hypno-toad.

Offline Magilla

  • Expert
  • ****
  • Posts: 764
  • My bike: 1976 CB750F
Re: Beginner to paint
« Reply #1 on: October 03, 2012, 03:54:46 PM »
What do you want your paint to look like when your done?  Flat, satin, deep gloss?  Metal flake?  Large flake or small?  Candy or not candy?  I can give a few pointers but I need more information.
1972   Honda CB350
1972   Yamaha 500
1982   Yamaha 650
1988   Harley Sportster 883
1983   HD FXR Shovelhead
2003   HD Heritage Softail
2006   Victory Vegas Jackpot
1980   Honda CB650
1976   Honda CB750K
1982   Honda CB750
1964   Honda CA95
1982   Kawasaki 550
1974   Honda CL360
1975   Suzuki GT550
1981   Honda CB750
1981   Honda CB750
1970   Norton Commando
1972   Yamaha U7E
1970   BMW R50/5
1976   Honda CB750F

Offline Motoguy23

  • Enthusiast
  • **
  • Posts: 208
Re: Beginner to paint
« Reply #2 on: October 03, 2012, 03:56:43 PM »
Gloss, metal flake, large flake, and candies are what I'm into right now.
All glory to the hypno-toad.

Offline piute

  • Piute
  • Full Member
  • *
  • Posts: 98
  • TRICK OR TREAT...B....es
Re: Beginner to paint
« Reply #3 on: October 03, 2012, 06:07:14 PM »
  I've painted for years ,Prep is the most inportant part ,Try to use all the same company product,Go to a reliable Auto paint seller such as P.P.G. (there all over) .There all over even up there in Minasota ? I can't remember the name of the place i used in Wisconsin but they sold everthing to do with auto body,These guys should know there stuff if not find one that works there that does.Best to use what is avaulable and easy to get(at home).They have all the mixes and each paint is different in ruducer flow as well as fish-eye killers.

  My brother is still in Wisconsin,Has his own shop N very tallented in candy's N flakes. Check out Magic on Metal on Face Book

   Few pics on hand
« Last Edit: October 03, 2012, 06:11:36 PM by piute »
Ride to live Live for Jesus
1977 750 F2

Offline piute

  • Piute
  • Full Member
  • *
  • Posts: 98
  • TRICK OR TREAT...B....es
Re: Beginner to paint
« Reply #4 on: October 03, 2012, 06:15:57 PM »

 to bigg
Ride to live Live for Jesus
1977 750 F2

Offline jamesb

  • Expert
  • ****
  • Posts: 1,167
Re: Beginner to paint
« Reply #5 on: October 03, 2012, 06:28:29 PM »
take your time and be patient. prepping is the key factor.if your into candy colors and flake determine what colors you want my chopper is getting a silver base then clear it with silver flake then add the candy colors. my son and i started with single stage paint it is the easiest to spray.there are different single stage colors metallics,flats,gloss,and satins. it gets more time consuming with base/clear coats.with those you have to wet sand and buff. single stage if you spray it good you really don't have to buff the paint out.also if you have old bike parts laying around(tank,side covers,fork ears,and headlight buckets.)start with those. rust-oleum makes a enamel that is pretty cheap it's a good starter for practice. don't need any drugs to shoot it.this way you can get the feel of the gun learn how much to spray so you don't orange peel or fish eye.at least with the cheap stuff your not out much if you screw it up.remember it can be resanded plus if your parts turn out you can sell them make a little extra cash to fund your main project.if you go to bare metal when prepping you have to use a etching primer if not then a primer sealer.take your time and have fun it's a lot easier than you think.
I've done a lot of things in my life that I'm not proud of...and the things I AM proud of, "are disgusting"

Offline ncstatecamp

  • Expert
  • ****
  • Posts: 799
Re: Beginner to paint
« Reply #6 on: October 03, 2012, 07:25:01 PM »
bump on the differences in paints!

anyone got a suggestion for best paint to use for tanks thats fuel resistant? I dont want my paint job eating away the first time theres splash from an over zealous fuel pump nozzle.....

Offline jamesb

  • Expert
  • ****
  • Posts: 1,167
Re: Beginner to paint
« Reply #7 on: October 03, 2012, 09:10:28 PM »
lacquer will start to check if to much is spilled on it over a period of time. single stage is practically bullet proof urethane is good.i've seen enamel paint hold up pretty good. all of it does need time to cure. to get the best results. you get what you pay for so keep that in mind.
I've done a lot of things in my life that I'm not proud of...and the things I AM proud of, "are disgusting"

Offline Magilla

  • Expert
  • ****
  • Posts: 764
  • My bike: 1976 CB750F
Re: Beginner to paint
« Reply #8 on: October 04, 2012, 03:28:17 AM »
It's not so much what paint to use for gas protection as it is what clear to use. Also if you want to do big flake you don't need paint.  The bike gets its color from the flake.  Use a urethane primer to seal the tank (so rust does not bleed through". Then mix the flake with the correct clear and spray.  Don't use more than three coats of this.  Then clean your gun, clean your gun and en clean your gun.  Then it's time for clear.  It will take a bunch of coats.

If any of your coats of primer or clear fully dry before you are ready to shot it again, you need to wet sand it.  When you sand it you need to clean it spotless before you spray it again.  Wet it.  Wipe it.  Blow it dry.  Wipe it again and then use tacky towels to pull up any dust.  I can't stress enough how important cleaning is. 
1972   Honda CB350
1972   Yamaha 500
1982   Yamaha 650
1988   Harley Sportster 883
1983   HD FXR Shovelhead
2003   HD Heritage Softail
2006   Victory Vegas Jackpot
1980   Honda CB650
1976   Honda CB750K
1982   Honda CB750
1964   Honda CA95
1982   Kawasaki 550
1974   Honda CL360
1975   Suzuki GT550
1981   Honda CB750
1981   Honda CB750
1970   Norton Commando
1972   Yamaha U7E
1970   BMW R50/5
1976   Honda CB750F

Offline lrutt

  • Expert
  • ****
  • Posts: 916
Re: Beginner to paint
« Reply #9 on: October 04, 2012, 05:21:41 AM »
To learn with, you should start with a solid color, and single stage IMO. I like acrylic enamel. Pretty tough and easy to apply. easy to touch up, wet sand, polish to a nice finish. Metalics and metal flakes are tough as if you don't get it right you get a lot of streaking and looks like crap. Gun technique is everything with those.

So start off easy. Pick a nice solid color, black, red, whatever. Urethanes etc. require a whole different level of personal protection equipment. Enamels with hardners not near as much.

Here is just a small sample of bikes I've done with acrylic enamels (with hardner). Oh, and you can do a very decent job using even an HF HVLP gun. the Guzzi and MG were done with that. The others with an old CH high pressure gun.





06 Harley Sporster 1200C, 06 Triumph Scrambler, 01 Ducati Chromo 900, 01 Honda XR650L, 94 Harley Heritage, 88 Honda Hawk GT, 84 Yamaha Virago 1000, 78 Honda 750K w/sidecar, 77 Moto Guzzi Lemans 850, 76 Honda CB750K, 73 Norton 850, 73 Honda Z50, 70 & 65 Honda Trail 90, 70 & 71 Triumph 650s, 65 Honda 305 Dream, 81 Honda 70 Passport, 70 Suzuki T250II, 71 Yamaha 360 RT1B, 77 BMW R75/7, 75 Honda CB550K, 70 Honda CT70

Offline Lars

  • Hot Shot
  • ***
  • Posts: 449
Re: Beginner to paint
« Reply #10 on: October 04, 2012, 05:42:00 AM »
You can also buy sets of paint here:

http://www.vintagehondapainting.com/   or  http://www.ct70paint.com/

Made by guys who knows about painting and have spesialised in old Honda's.
...if you got the ability to act...

Offline bjatwood

  • I never claimed to be an
  • Expert
  • ****
  • Posts: 976
  • 1973 CB750-K3
    • Minbikers Proboards
Re: Beginner to paint
« Reply #11 on: October 04, 2012, 08:48:55 AM »
I've used the Vintage Honda paints before on 3 bikes. I am NOT a painter, but the kits if you follow them to a tee work great! HVLP guns work well for these kits. Good Luck  ;)
Brian
#24193

I believe that the Finest things are the most thoughtfully made, not the most expensive!
http://minibikers.proboards.com/

Offline Magilla

  • Expert
  • ****
  • Posts: 764
  • My bike: 1976 CB750F
Re: Beginner to paint
« Reply #12 on: October 04, 2012, 09:22:51 AM »
ILMO gave solid advice.  Start simple.  Single stage color.  Go to any GOOD auto paint store and they will help you with what you need to buy.  It wont be cheap.  You will have to buy more paint, activators and hardeners than you need.  They just don't sell small sizes.  Estimate around $300 and you should be close.

A good paint job is all about the prep work.  Strip your tank to metal.  Don't give in to the temptation of sanding the old paint and thinking you can paint over it.  Buy a grinder and a wheel and strip it.  DONT use this on your side covers.  They have to be hand sanded.  It takes a long time to do it right.  I had about 10 hours per cover if I remember it correctly.  it was well worth it.  if you have paint that stick in a corner and you cant sand it, use a small knife with a point to pick it out.  You will be glad you did. 

Once you've done this, start sanding each item with finer paper all the way to wet sanding it.  Get it smooth.  If you need body filler for any dents now is the time to apply it.  Skim it all over the affected area don't try to just fill the hole.  don't slop it on either.  Skim coat it.  The after it dries, sand it.  sand it until its smooth and the skim it again if it needs it.  Repeat until you cant feel it any longer.  once its all smooth sanded and CLEAN you are ready for primer.

Don't try to skip the primer.  You need a sealing primer or rust WILL bleed through.  Prime it and let it dry.  Sand it and CLEAN it.  Then your ready for paint.  after each coat of paint you need to wait about 20-30 minutes for it to get tacky.  if you don't wait that long it will run on you.  Paint until you get the desired effect.  Paint your tank and covers at the same time.  Don't plan to do it another day.  depending on how you mix your prodcuts the colors may not match.  once everything is painted, leave it alone for a day.

Before you can clear you need to inspect everything.  See if there are any blemishes that need to be addressed.  most can be wet sanded out.  You need to wetsand no matter what because your paint is completely dry now so clear wont stick to it.  After you sand it, CLEAN it.  Use a tacky pad to help remove the dust.  Now its time for clear.  Apply it just like paint.  20-30 minutes between coats.  Only you can know how many coats of clear you want.  it will shine after one.  A second and third will give it some durability.  After that it is about creating a deep look to it.  Once your done let it sit for a day.

Now you have to sand your shine off.  What did I just say?  Yes sand it off with a very fine wetsand paper.  This will remove orange peel and will remove any dust you have.  Now you ll need 2 stages of buffing compounds.  One to remove swirls.  Buff it out and stay away from corners and edges our you will buff right into the paint.  The second stage is a fine line/swirl remover.  Same buffing process.  Your paint job is now done.  Good for you.  The buffing should only take you about 30 minutes for all 3 pieces.  it goes quickly.
1972   Honda CB350
1972   Yamaha 500
1982   Yamaha 650
1988   Harley Sportster 883
1983   HD FXR Shovelhead
2003   HD Heritage Softail
2006   Victory Vegas Jackpot
1980   Honda CB650
1976   Honda CB750K
1982   Honda CB750
1964   Honda CA95
1982   Kawasaki 550
1974   Honda CL360
1975   Suzuki GT550
1981   Honda CB750
1981   Honda CB750
1970   Norton Commando
1972   Yamaha U7E
1970   BMW R50/5
1976   Honda CB750F

Offline Motoguy23

  • Enthusiast
  • **
  • Posts: 208
Re: Beginner to paint
« Reply #13 on: October 04, 2012, 09:32:49 AM »
thank you guys for the advice!
All glory to the hypno-toad.

Offline ncstatecamp

  • Expert
  • ****
  • Posts: 799
Beginner to paint
« Reply #14 on: October 04, 2012, 10:12:14 AM »
ILMO gave solid advice.  Start simple.  Single stage color.  Go to any GOOD auto paint store and they will help you with what you need to buy.  It wont be cheap.  You will have to buy more paint, activators and hardeners than you need.  They just don't sell small sizes.  Estimate around $300 and you should be close.

A good paint job is all about the prep work.  Strip your tank to metal.  Don't give in to the temptation of sanding the old paint and thinking you can paint over it.  Buy a grinder and a wheel and strip it.  DONT use this on your side covers.  They have to be hand sanded.  It takes a long time to do it right.  I had about 10 hours per cover if I remember it correctly.  it was well worth it.  if you have paint that stick in a corner and you cant sand it, use a small knife with a point to pick it out.  You will be glad you did. 

Once you've done this, start sanding each item with finer paper all the way to wet sanding it.  Get it smooth.  If you need body filler for any dents now is the time to apply it.  Skim it all over the affected area don't try to just fill the hole.  don't slop it on either.  Skim coat it.  The after it dries, sand it.  sand it until its smooth and the skim it again if it needs it.  Repeat until you cant feel it any longer.  once its all smooth sanded and CLEAN you are ready for primer.

Don't try to skip the primer.  You need a sealing primer or rust WILL bleed through.  Prime it and let it dry.  Sand it and CLEAN it.  Then your ready for paint.  after each coat of paint you need to wait about 20-30 minutes for it to get tacky.  if you don't wait that long it will run on you.  Paint until you get the desired effect.  Paint your tank and covers at the same time.  Don't plan to do it another day.  depending on how you mix your prodcuts the colors may not match.  once everything is painted, leave it alone for a day.

Before you can clear you need to inspect everything.  See if there are any blemishes that need to be addressed.  most can be wet sanded out.  You need to wetsand no matter what because your paint is completely dry now so clear wont stick to it.  After you sand it, CLEAN it.  Use a tacky pad to help remove the dust.  Now its time for clear.  Apply it just like paint.  20-30 minutes between coats.  Only you can know how many coats of clear you want.  it will shine after one.  A second and third will give it some durability.  After that it is about creating a deep look to it.  Once your done let it sit for a day.

Now you have to sand your shine off.  What did I just say?  Yes sand it off with a very fine wetsand paper.  This will remove orange peel and will remove any dust you have.  Now you ll need 2 stages of buffing compounds.  One to remove swirls.  Buff it out and stay away from corners and edges our you will buff right into the paint.  The second stage is a fine line/swirl remover.  Same buffing process.  Your paint job is now done.  Good for you.  The buffing should only take you about 30 minutes for all 3 pieces.  it goes quickly.

Can we get this stickied somewhere?

Offline lrutt

  • Expert
  • ****
  • Posts: 916
Re: Beginner to paint
« Reply #15 on: October 04, 2012, 11:55:32 AM »
And....if you need a nice clean environment to paint, and plan on doing more painting, you can get a portable paint booth. When I painted my MG I bought one of those 12 x 22' fully enclosed portable garages from Northern Tool. It was like $279. Took a couple hours to put up. I used a large poly tarp for the flloor, hung some 500w halo lights on the side walls, ran my air line out there and located a regulator and water trap out there. Set this up next to my garage. The pipe structure provides a natural location for haning wires for suspending parts. The protection keeps bugs and dust off. I wet the floor prior to painting. I also put a box fan on one end to draw fresh air through, had a simple filter on the other end. Basically a fully enclosed paint room for $300. When I was done I took it all down in about an hour and boxed it up for the next paint project.

Best $300 I spent for painting. No worries about moving wet parts, crap getting on them, rain, direct sun, bugs, etc. etc.

Here is a pic of my setup.



06 Harley Sporster 1200C, 06 Triumph Scrambler, 01 Ducati Chromo 900, 01 Honda XR650L, 94 Harley Heritage, 88 Honda Hawk GT, 84 Yamaha Virago 1000, 78 Honda 750K w/sidecar, 77 Moto Guzzi Lemans 850, 76 Honda CB750K, 73 Norton 850, 73 Honda Z50, 70 & 65 Honda Trail 90, 70 & 71 Triumph 650s, 65 Honda 305 Dream, 81 Honda 70 Passport, 70 Suzuki T250II, 71 Yamaha 360 RT1B, 77 BMW R75/7, 75 Honda CB550K, 70 Honda CT70

Offline Magilla

  • Expert
  • ****
  • Posts: 764
  • My bike: 1976 CB750F
Re: Beginner to paint
« Reply #16 on: October 04, 2012, 12:31:33 PM »
And....if you need a nice clean environment to paint, and plan on doing more painting, you can get a portable paint booth. When I painted my MG I bought one of those 12 x 22' fully enclosed portable garages from Northern Tool. It was like $279. Took a couple hours to put up. I used a large poly tarp for the flloor, hung some 500w halo lights on the side walls, ran my air line out there and located a regulator and water trap out there. Set this up next to my garage. The pipe structure provides a natural location for haning wires for suspending parts. The protection keeps bugs and dust off. I wet the floor prior to painting. I also put a box fan on one end to draw fresh air through, had a simple filter on the other end. Basically a fully enclosed paint room for $300. When I was done I took it all down in about an hour and boxed it up for the next paint project.

Best $300 I spent for painting. No worries about moving wet parts, crap getting on them, rain, direct sun, bugs, etc. etc.

Here is a pic of my setup.




Very nice. I love it.
1972   Honda CB350
1972   Yamaha 500
1982   Yamaha 650
1988   Harley Sportster 883
1983   HD FXR Shovelhead
2003   HD Heritage Softail
2006   Victory Vegas Jackpot
1980   Honda CB650
1976   Honda CB750K
1982   Honda CB750
1964   Honda CA95
1982   Kawasaki 550
1974   Honda CL360
1975   Suzuki GT550
1981   Honda CB750
1981   Honda CB750
1970   Norton Commando
1972   Yamaha U7E
1970   BMW R50/5
1976   Honda CB750F

Offline lrutt

  • Expert
  • ****
  • Posts: 916
Re: Beginner to paint
« Reply #17 on: October 04, 2012, 12:56:50 PM »
Also....for supplies....I go to TCPGlobal.com. Very reasonable prices. Although it can be very helpful to create a relationship with a local paint supply house, if they are local. Not always the case though. I don't like having to drive an hour to get stuff, and them not be open on saturdays etc. PITA. TCP is quick shipment and very reasonable for all supplies, degreaser, reducer, hardner, paint, primer, sealer, fish eye killer, mixing cups, filters, etc.
06 Harley Sporster 1200C, 06 Triumph Scrambler, 01 Ducati Chromo 900, 01 Honda XR650L, 94 Harley Heritage, 88 Honda Hawk GT, 84 Yamaha Virago 1000, 78 Honda 750K w/sidecar, 77 Moto Guzzi Lemans 850, 76 Honda CB750K, 73 Norton 850, 73 Honda Z50, 70 & 65 Honda Trail 90, 70 & 71 Triumph 650s, 65 Honda 305 Dream, 81 Honda 70 Passport, 70 Suzuki T250II, 71 Yamaha 360 RT1B, 77 BMW R75/7, 75 Honda CB550K, 70 Honda CT70

Offline gto_ron

  • Enthusiast
  • **
  • Posts: 125
Re: Beginner to paint
« Reply #18 on: October 04, 2012, 01:10:26 PM »
All the posts contain great advice.  Just to add,  whether you're down to bare metal or painting over a faded but solid previous paint job;  use epoxy primer as your first primer coat and as your last sealer coat.  Forget lacquer, that's old school and scratches and chips easily.  Basecoat/clearcoat is the way to go.  Urethane enamel is good but BC/CC gives a deeper gloss.

The best source for painting materials that I've found is SPI Polyurethanes.  Barry is the owner and answers the phone, he gives great advice and all shipping is free.  I've used all the name brands over the last 30 years and nothing beats SPI.  The prices are 1/2 the name brand paints.  I just finished the GTO in the attached pic with SPI clearcoat.

regards

Ron
Ron


76 CB750K
72 CB350F
64 GTO

why yes, I am old-school, so what? 

These are the good old days.

Offline ncstatecamp

  • Expert
  • ****
  • Posts: 799
Beginner to paint
« Reply #19 on: October 04, 2012, 07:32:46 PM »
All the posts contain great advice.  Just to add,  whether you're down to bare metal or painting over a faded but solid previous paint job;  use epoxy primer as your first primer coat and as your last sealer coat.  Forget lacquer, that's old school and scratches and chips easily.  Basecoat/clearcoat is the way to go.  Urethane enamel is good but BC/CC gives a deeper gloss.

The best source for painting materials that I've found is SPI Polyurethanes.  Barry is the owner and answers the phone, he gives great advice and all shipping is free.  I've used all the name brands over the last 30 years and nothing beats SPI.  The prices are 1/2 the name brand paints.  I just finished the GTO in the attached pic with SPI clearcoat.

regards

Ron

What type of paint stands up best to gasoline spillage?

Offline gto_ron

  • Enthusiast
  • **
  • Posts: 125
Re: Beginner to paint
« Reply #20 on: October 04, 2012, 08:05:07 PM »
both urethane enamel and BC/CC stand up well to gasoline, I haven't used lacquer in so long I forget how well it does or doesn't handle gas.

GM used lacquer back in the 50's and 60's and the cars looked great.  Since then the EPA has mandated the removal of lead from paints(for good reason), as a result the lacquer selling now isn't as bright or as durable as it used to be.

regards

Ron
Ron


76 CB750K
72 CB350F
64 GTO

why yes, I am old-school, so what? 

These are the good old days.

Offline LesterPiglet

  • Old Timer
  • ******
  • Posts: 4,045
  • 1977 CB550F2
Re: Beginner to paint
« Reply #21 on: October 05, 2012, 06:16:31 AM »
I have found cellulose to be the most forgiving paint to use as a learner. Easy to work with and correct. Not much needed equipment wise.
'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


Les Ross.            Certified by a Professional

Offline ncstatecamp

  • Expert
  • ****
  • Posts: 799
Beginner to paint
« Reply #22 on: October 05, 2012, 04:25:32 PM »
I asked the guys over at dotheton and they suggested this stuff http://www.spraymax.com/index.php?id=361&L=1

Anybody tried this?

Offline piute

  • Piute
  • Full Member
  • *
  • Posts: 98
  • TRICK OR TREAT...B....es
Re: Beginner to paint
« Reply #23 on: October 05, 2012, 05:06:11 PM »
    Lil mo,
 Shooting BIGG Flakes is not for the beginner,The air presure has to be perfect,Special size tips,as well as the mix ,these big azz peaces have to lie down flat (witch is almost impossible by the way) With lots of use you can get it but the $$ is going to bite ya, I like to mix 2 sizes maybe even different colors ,just to help hide the high edges and remember your clear has to be even higher above that edge , IF you were to sand down you could tell when you hit the flake then to late,My problem with clear I always lay it on heavy (just before runs)take practice to get fill,(so lil orange peel/gotta sand)but thick as a sucker.
   I do lots of painting using bombs(cans) Rustolium my fav.,Lots of wax never have I had a problem with gas(damage to paint) on anything I paint/done. Lots of wax,sure you may see were it over flowed but only damaged wax.
    Pics of bomb job (my tank past year)Hey Love to paint Ideas,
                           Bigg Gold Flakes come spring.
« Last Edit: October 05, 2012, 05:10:34 PM by piute »
Ride to live Live for Jesus
1977 750 F2

Offline Magilla

  • Expert
  • ****
  • Posts: 764
  • My bike: 1976 CB750F
Re: Beginner to paint
« Reply #24 on: October 10, 2012, 07:58:30 AM »
Status update?
1972   Honda CB350
1972   Yamaha 500
1982   Yamaha 650
1988   Harley Sportster 883
1983   HD FXR Shovelhead
2003   HD Heritage Softail
2006   Victory Vegas Jackpot
1980   Honda CB650
1976   Honda CB750K
1982   Honda CB750
1964   Honda CA95
1982   Kawasaki 550
1974   Honda CL360
1975   Suzuki GT550
1981   Honda CB750
1981   Honda CB750
1970   Norton Commando
1972   Yamaha U7E
1970   BMW R50/5
1976   Honda CB750F