[Chain]

Can I get some quick advice. Is it OK to seal a routed track in PVA? And if so, what kind of PVA to water mixture should I do?

I put a magnetic paint coat down yesterday, waited 10 hours, then put down a top coat of water based grey paint. For some reason, the magnetic paint does not appear to have cured (felt fine to paint over, and time between coats is 3 hours according to the tin) and the water based top paint can scratch off quite easily.

I'm painting road markings and skid marks today, with the intention of doing copper tape tomorrow or Sunday. Before doing the tape I need to decide if PVA would work, otherwise I fear the paint will chip and scratch in use.

Thank you

 

[hankscorpio]

PVA will give a good seal as long as the paint is nice and dry... but it will give a lot of extra grip... unsure if thats a good thing or not

 

[keysandslots]

Paint is odd stuff. Check the directions on your magnetic paint but I've noticed with some that you need to apply subsequent coats either within an hour or so, or wait a few days. There are also restrictions on what kind of of paint can be applied over a different kind of paint, such as latex over oil and that sort of thing, although I can't remember the details.

I've never heard of anyone top-coating with PVA, I would just wait a few days and apply another top coat of flat latex or something like that.

Randy

 

[Chain]

Thanks for the fast replies. Another coat isn't really viable as I've spent all day detailing the track, so it looks like asphal. Would have to said it down to add another coat

Will the magnetic paint (which is solvent based) cure even under the water based paint if I leave it long enough? I don't think it will. I've done a test and scratched off the water based paint (it won't scratch off on areas without the magnetic paint) and the magnetic paint is tacky!

I'm not very happy

There must be something I can coat everything with to seal it. Just how "grippy" would PVA be if it was really diluted?

 

[keysandslots]

The problem with sealing it is that the solvent-based paint will "off-gas" for a few days at least. If you seal it now, you may end up with bubbles or other odd things.

Let it dry for a week and the decide.

Randy

 

[Black3sr]

Sure made it complicated. Scrape and sand and put down one or two coats of flat latex.. Forget the magnetic. Turn the power down a bit and tune for nonmag.

 

[pfj]

Hi, there was a post some time ago about problem's useing magnetic paint the track was getting power drop's between lane's the cause the paint was in the slot and was causeing the power to pass along the track surface to other' so make sure you have seperation between lane's. pfj

 

[highbarn]

The "3 hours between coats" time is for subsequent coats of the same paint not for a final cured finish. The last thing you want to do is seal that solvent based paint so that it can't completely cure. I agree with the others that recommend letting it sit for a few days and seeing what happens.

 

[AAWSCC]

I had a tin of magnetic paint which I used on the Pioneer test track I built last year. The paint 'went off' good enough and we painted over with household water based emulsion without any problems. I would say you should leave it to dry for 24 - 48 hours before painting over and I agree with the others that sealing it now will just seal in the uncured paint.
The really annoying bit is that the magnetic paint doesn't actually give any effect. Fine if you are making a kitchen notice board with the mags directly on to the board, but no good for slot cars with a gap. We even tried adding iron fillings from a local steel works to 'beef' up the paint.

I would imagine that you have a bumpy surface to tape to as well, unless you masked off where the copper tape will go. I always tape before painting. That way you get the copper and the track surface at the same level.

 

[GT40's]

I used similar paint to what you mentioned, Black magnetic paint base with waterbased craft paints over it ,then road markings and detailing. After painting I sealed it all with watered down white glue & the tape went on.I dont know how it compares to other methods cos its all ive tried so far but im happy with it. The magnetic paint was a waste of money though as it hardly changes anything! And I didnt paint into the slots with the magnetic paint ,just on top. The magnetic paint had 2-3 days to cure after I aplied a couple of coats.

 

[Ade]

hi
a bit late with this info but D2 pva will dry to a white colour and D3 will dry clear..

 

[MrFlippant]

Although not as effective as steel rails, the magnetic paint DOES have some effect:

QUOTE two identical hornby mustang slot cars on a section of my wood track. track is painted with 2 coats of rustoleum magnetic primer with one coat of behr interior flat paint on top. first car has no magnets installed. second car has a single bar magnet in the rear position. huge difference in traction...

for this test, both cars were powered with two 9 volt batteries held directly to the rails.

 

[Mark0]

How many coats of magnetic were on there Mr F

-Mark0 <--still getting ready to re-rout the errors (been sitting on the magnetic paint so long now it's probably RUSTED!!)

 

[MrFlippant]

see quotation of video description
by the way, that's not my track, but I'd seen that video a while ago and it seemed appropriate to post here.

 

[Chain]

Thanks for all the advice guys.

I put on two coats of magnetic paint, which was pretty much the whole 750ml tin. Simple tests show it to have just about no effect, so yeah I too am convinced it was a waste of time and money. If I'd done 5 or 6 coats it may of been different.

The best bet right now appears to be wait and see. I'll carry on detailing and won't tape it for at least a few days. It's not like there isn't a hundred and one other things to be getting on with on the track. I'll do some tests in a few days to see if it still scrapes easily, I'm hoping the water based paint it porous enough to allow the solvent paint under it to cure.

Thank you all so much for the advice. This track has proved to be such a time eater, there's just one issue after another and this paint issue freaked me out. I'll let you all know what the situation is in few days time

 

[MrFlippant]

I wouldn't call it a waste of time just yet. It doesn't take much pull to improve traction dramatically as shown in that video, but you won't FEEL it if you put a car on that has a magnet in it and lift it off the track like you can with a magnet car on steel rails. Between absolutely no pull (no magnet or ferrous paint) and a little pull (magnet and ferrous paint), there's a difference in the car performance. Will the kids be able to tear around at high speed without coming off? Of course not. Nor could they have on plastic with steel rails and silicone tires. You'll still need to reduce their power scale and/or track voltage to help them stay on while they learn how to race with very low magnetic downforce.
The annoying part is that the paint needs a long time to fully dry/cure/whatever prior to a top coat. This is information I had not known, so will be useful to keep in mind when other people ask about using magnetic paint on a routed track.

I really hope that time will cure the problem and you can continue as planned. I think it's good that you didn't tape first, though. No one ever gets anything done on a track once you can make a car go on it. ;-)

 

[AAWSCC]

Don't take this the wrong way MR.F, but I find it hard to see that it's the paint making the difference in your video. Where the car has better traction is where the rails are close together so you have the extra thickness of the tape and the lack of MDF/paint because the car is over the slots. I would put that down to one car having better tyres than the other.
Plus testing with a battery directly onto the copper is not the most consistant way to find out.
We put 6 coats with extra iron fillings in the paint and still not much magnetic effect.

 

[GT40's]

Just another note on aplying copper tape on PVA paint ,in hindsight and for future Ill try some sticky glue before putting down the tape as its more likely to come off or wrinkle due to wheather changes on a phorus PVA than on latex paint.

And about the magnet traction on routed wood tracks, another way is to inbed mettal wires in routed slots and cover it up.

 

[martini917k]

magnabraid

 

[MrFlippant]

I'm fully prepared to believe that the magnetic paint has little effect. At the same time, I know Boopiejones from more than that video, and have no reason to doubt him. I guess the only way to prove it is to take the SAME car and do it once with a magnet and once without.

I also am well aware that the tires probably make more difference than the magnetic paint. I've run magless enough to know that, and when I make my own wood track(s), I'll probably not use the magnetic paint I have on hand. House paint and proper tires is all I'm planning on worrying about.