DIY Painting Tips

[mojo]

Hey ducpainter.  I have the "Ducati Dent" in my tank and I'm planning on fixing it sometime soon.  Question is, would it be safe to use a Uni-Spotter to pull the dent if I let the tank air out and fill it with water?  There doesn't seem to be any access from the inside to push it out because of the baffles inside the tank.  Thanks in advance.

[ducpainter]

Hey ducpainter.  I have the "Ducati Dent" in my tank and I'm planning on fixing it sometime soon.  Question is, would it be safe to use a Uni-Spotter to pull the dent if I let the tank air out and fill it with water?  There doesn't seem to be any access from the inside to push it out because of the baffles inside the tank.  Thanks in advance.

Uni-spotter is a brand name for a stud welder.

I use one made by Motor-guard.

They work great.

Go slow...it's easy to pull a chunk of the tank out or crack the metal.

It takes patience and some skill.

Make sure you braze the hinge and coat the tank.

Might as well do the job right the first time.

[mojo]

Is it necisary to fill the tank with water? Or can I just let it air out?  Also, what product would you recommend to use for sealing the inside of the tank when finished? 

Is the hinge area of the tank a weak spot that has caused problems?

[ducpainter]

Is it necisary to fill the tank with water? Or can I just let it air out?  Also, what product would you recommend to use for sealing the inside of the tank when finished? 

Is the hinge area of the tank a weak spot that has caused problems?

If the tank is clean inside...

meaning no heavy rust scale just let it dry. If you're the nervous type you can rinse it out

Heavy scale will trap fuel and they can go poof when you braze. I've had those go boom even after rinsing. It's kinda cool...flames shoot out the sender hole I've never had one do it from the stud welder.

The Monster tank hinge goes back to the days if the 851/pre Terblanche SS. Back then they used a couple of reinforcement welds from the hinge to the tank seam along with the spot welds. Those didn't leak.

When they introduced the monster and the Terblanche designed SS for some reason they eliminated the reinforcement welds...probably to reduce costs...and lo and behold. The spot welds failed.

Trust me on this one. Reinforce the hinge.

I use POR-15 and have never had a complaint of a failure. Follow the instructions exactly and you should have no problem.

BTW make sure you remove all the internals before starting the project.

[mojo]

Thanks for the help.  I do body work for a living, but I've never fixed a dent on a gas tank.

BTW, it's cool to see that you are giving so many people good advice on how to their own paint work.  I've read through this whole thread, and I think that I agree with just about everything you've told people...it's nice to see a good body man/painter who isn't a hack, cuz there seems to be more hacks than there are people who know what their doing.

Thanks again

[ducpainter]

No problem...

I enjoy doing it.

I can't emphasize how important going slow with the studs are.

The metal thickness on the monster tank and the shape makes it really easy to end up welding a bunch of holes up. 

Let me know if I can be of any more help.

[red baron]

I'm a hack, what of it?

[ducpainter]

I'm a hack, what of it?

Yeah....

right.

[Langanobob]

I use a sandable modified epoxy surfacer, an activated urethane sealer, urethane base and activated acrylic urethane clear.

After getting a lot of different and confusing advice on primers from the paint store, for the last couple of painting projects I've ended up using a two-part epoxy primer.  I think it says "non-sanding" right on the cans, but I wet sand it and it sands very nicely.  I really like the two part epoxy primer, it sprays good and is a light gray which seems to work good under the colors I've used, and it sticks like iron to bare steel.  Then I use use a two-part urethane base coat right over the primer with no activated urethane sealer.   My paint jobs seem to always have a few flaws, directly traceable to not having a spray booth and not having a lot of skill, but I haven't noticed any issues at all with the materials;  the paint looks good and is very durable.

I have two questions:

1.  Is there any reason I should not sand  the "non-sanding" primer?
2.  Am I missing something by not using an activated urethane sealer over the epoxy primer before applying the base coat?

Thanks,

Bob

[ducpainter]

After getting a lot of different and confusing advice on primers from the paint store, for the last couple of painting projects I've ended up using a two-part epoxy primer.  I think it says "non-sanding" right on the cans, but I wet sand it and it sands very nicely.  I really like the two part epoxy primer, it sprays good and is a light gray which seems to work good under the colors I've used, and it sticks like iron to bare steel.  Then I use use a two-part urethane base coat right over the primer with no activated urethane sealer.   My paint jobs seem to always have a few flaws, directly traceable to not having a spray booth and not having a lot of skill, but I haven't noticed any issues at all with the materials;  the paint looks good and is very durable.

I have two questions:

1.  Is there any reason I should not sand  the "non-sanding" primer?
2.  Am I missing something by not using an activated urethane sealer over the epoxy primer before applying the base coat?

Thanks,

Bob

The only reason for not sanding is that type of primer is not really intended to fill like a primer-surfacer. Are you using DP-40?

If you apply enough to fill you have generally applied too much, and it's also possible you don't have sufficient film for it to work as a corrosion protectant if you sand too much.

Activated sealers promote adhesion to primers and also can help with coverage depending on the color of sealer/topcoat. I like them and believe it makes for a better job. I do sometimes spray over the type of epoxy primer you are referring to, slightly reduced to improve flow, but I spray wet on wet without sanding.

You might try HOK KD-2000. It is the modified epoxy I was referring to. It has the benefit of excellent adhesion, corrosion resistance, and it fills great making it a good choice as a direct to metal primer-surfacer.

For the record, the system you are using is great as long as you end up with enough primer after sanding. You could also spray an additional coat of epoxy, slightly reduced, to ensure adequate film thickness.

[red baron]

1.  Is there any reason I should not sand  the "non-sanding" primer?
2.  Am I missing something by not using an activated urethane sealer over the epoxy primer before applying the base coat?

It's called non sanding because it's engineered to go on smooth enough to accept topcoat without "having" to sand it.

+1 on dp's recommendation of using a sealer coat and I'll add to it that it also creates a fresh chemical bond as well. Using the sealer will also allow you to use a grit or so coarser keeping bodywork straighter.

If you're into House of Kolor and in an unregulated market, the KP2CF is the bomb. Although it only comes in a crappy green color, it's an awesome primer that will never let you down.

[Langanobob]

Ducpainter and trouble, thanks for your comments.

The only reason for not sanding is that type of primer is not really intended to fill like a primer-surfacer. Are you using DP-40?

I've been using Nason Ful-poxy primer, mainly because the store that sells it is close.  I think it may be very similar to DP-40 but don't know for sure.

Activated sealers promote adhesion to primers and also can help with coverage depending on the color of sealer/topcoat. I like them and believe it makes for a better job. I do sometimes spray over the type of epoxy primer you are referring to, slightly reduced to improve flow, but I spray wet on wet without sanding.

I'm not quite there yet to spray wet on wet.  All my paint projects so far have required some remedial work in between coats.

You might try HOK KD-2000. It is the modified epoxy I was referring to. It has the benefit of excellent adhesion, corrosion resistance, and it fills great making it a good choice as a direct to metal primer-surfacer.

Thanks, I think I will try it next time.

[Langanobob]

The automotive paint store is always trying to sell me "Self Etching" primer for use on bare steel.  I'm no chemist but it just seems to me that anything that is self etching has to be acidic and it also seems to me that acid and paint are not very compatible and there must be some compromise in the coating quality of the primer due to the acid content.  For bare metal I've been using metal prep from the local big box store and it seems to work fine as long as I get it all off before priming.

Is self etching primer worth using?

Thanks,

Bob

[ducpainter]

The automotive paint store is always trying to sell me "Self Etching" primer for use on bare steel.  I'm no chemist but it just seems to me that anything that is self etching has to be acidic and it also seems to me that acid and paint are not very compatible and there must be some compromise in the coating quality of the primer due to the acid content.  For bare metal I've been using metal prep from the local big box store and it seems to work fine as long as I get it all off before priming.

Is self etching primer worth using?

Thanks,

Bob

My simple answer....

use epoxy.

The military does, as does every manufacturer, other than automotive, for items exposed to the elements.

Self etching was designed for speed. It does not have the corrosion resistance of the system you're currently using.

[Langanobob]

Thanks.  I've had these questions for a long time and I really appreciate you and others taking the time to share your knowledge.