Topic: VHT caliper paint, not expected result any input ?

[Viktor.J]

Hey guys, I need some help with VHT paint and curing.

I have never used VHT paints before so my experience with the products are limited.

I've been painting some glass-blastered aluminium parts. I cleaned them with acetone and "tak-rag" and wore plastic gloves at all time. 
As a primer I used the "Flame proof white, SP118" that's been recommended. First one thin layer, waited 10 minutes, then another thin layer, then waited 20 minutes and added the last wet layer. I hang them to dry for 7 days. After the 7 days I "dusted" them of with clean compressed air, then painted with Caliper paint SP734 or SP735, in same method as before.
I then waited for about 8 hours or more and cured them finally in the oven for 1 hour at 100C. After this I left them for 4-7 days. And while the paint is harder it's not that very hard, I can with ease make a scar. Is this the  expected result ?

As a solution I tried to cure them harder at 30 min at 200C because they are supposed to withstand up to 400C. But after 15 minutes at 200C the paint began to bubble up and doesn't look good at all.
Did I do anything wrong ? Since the pieces cant withstand half the temperature they are suposed to

The parts after the 200C curing




Or is this the quality that I should expect ?

Kindly regards
Viktor

[dave500]

ive used a lot of vht paints including engine and heat paints,i found with exhaust pipes its best not to use the white primer,now for exhausts i just use a cheaper bar b que heat paint and it seems to hold better,ive never baked any paint just used it as is.

[Viktor.J]

ive used a lot of vht paints including engine and heat paints,i found with exhaust pipes its best not to use the white primer,now for exhausts i just use a cheaper bar b que heat paint and it seems to hold better,ive never baked any paint just used it as is.

OK, thanks Dave. That's strange, you kind of think that if you follow their instructions you get the best result !

[dave500]

thats what i thought untill my exhaust pipes looked like a zebra!

[Lars]

My best advice when it comes to brake calipers, is to powder coat them flat black. No problem with brake fluids and looks good. And it is cheap.
Lars

[Viktor.J]

My best advice when it comes to brake calipers, is to powder coat them flat black. No problem with brake fluids and looks good. And it is cheap.
Lars

Called a couple of companies here in my town but they didn't want to do the job :S they didnt do motorcycle parts or not that small amount
That doesn't really help my now though..

[Retro Rocket]

Viktor, it looks like you put those parts in the oven wet ?, some of the bubbles could be contaminants coming out of the alloy. If i was doing old alloy parts i would clean them really well, heat them up first fairly hot, this will help oil and stuff to bleed or weep out of the alloy,  clean well while warm with some acetone to remove contaminants, prime with a good high temp primer, let it dry for a couple of days them paint the black and let it dry for a couple of days THEN bake them in the oven..... I may be fussy but it works for me....

[Viktor.J]

Viktor, it looks like you put those parts in the oven wet ?, some of the bubbles could be contaminants coming out of the alloy. If i was doing old alloy parts i would clean them really well, heat them up first fairly hot, this will help oil and stuff to bleed or weep out of the alloy,  clean well while warm with some acetone to remove contaminants, prime with a good high temp primer, let it dry for a couple of days them paint the black and let it dry for a couple of days THEN bake them in the oven..... I may be fussy but it works for me....

Nope, the where dry, at least I believe so, and actually the B-pad had been drying for over a week in room temperature. So they couldn't be wet. Your point on alloy contamination seems quite possible, never heard of it though so that's why I didn't take those precautions.  to clean them I used first a tack-cloth and then a clean rag soaked in acetone, then before paint cleaned with acetone again and let the acetone vapor and dry out before painting.
I Used the primer they recommended, dried for 7 days painted the color then waited 7 days.

SO the only explanation could be the alloy contaminations... 

[krusty]

To avoid brake fluid stripping paint, and absorbing water I now use silicone brake fluid Dot 5. Problem solved.

[MRieck]

Bead blast the parts, clean (I use lacquer thinner or Prep-Sol) and do not use primer. Do not put the paint on to thick.

[CycleRanger]

Bead blast the parts, clean (I use lacquer thinner or Prep-Sol) and do not use primer. Do not put the paint on to thick.

What he said. I have obtained my best results using VHT without primer.
Also, as mentioned above, baking prior to painting can help drive contaminants out of the sometimes porous aluminum.

[iron_worker]

I haven't used VHT but I have used Duplicolor high heat engine paint. The directions say to use primer but I couldn't find high heat primer anywhere. I asked around here and most guys just put it straight onto clean bare metal so that's what I did. I didn't bake all my parts but I did bake some. A few weeks later I'd say they all get to the same hardness eventually.

The way I read the instructions it sounds like if you want full hardness right away then you use the baking process. Otherwise, you have to wait a full 7 days to get to full hardness. This makes sense to me as the curing process is probably exponentially related to temperature... it's still happening at room temp just much more slowly.

IW

[Viktor.J]

I guess this is a answer to all of you guys !

Well then VHT sucks first, they tell me to use the primer and now it seems like I shouldn't. And I've left the part to dry both cured and un-cured and I'm not that satisfied with the paints mechanical resistance. Neither the temperatur resistance, since the parts cant be in a 200C oven.

[dave500]

is it very cold in your location at the moment?

[RAFster122s]

The paint you show is pretty thick to have the fingerprint impressions I think...  Some paints react with themselves and trap the outgassing of solvents.  Sometimes you just can't win with some paints...
 

[pickle fart]

I've used VHT caliper paint several times with excellent results. I blast  the parts with 'Trin-Mix' a mix of glass beads and aluminum oxide then blow off with air. I do not primer, and I definitely do not wipe the parts with acetone or any other cleaning fluids. I do three coats, then cook in an oven as per instructions.

[Retro Rocket]

I've used VHT caliper paint several times with excellent results. I blast  the parts with 'Trin-Mix' a mix of glass beads and aluminum oxide then blow off with air. I do not primer, and I definitely do not wipe the parts with acetone or any other cleaning fluids. I do three coats, then cook in an oven as per instructions.

There's no problem using acetone, prepsol or prepwash {all acetone or 100% hydrocarbon} thats what they are designed for...
I should have said earlier, i don't use VHT primer, i specialize in epoxy painting for industrial purposes so i have an ample supply of very good epoxy primer, that stuff sticks to almost anything...

[pickle fart]

I respectfully disagree, and from experience using acetone to clean and prep. I have found some paints or finished that don't work with acetone. I have painted and refinished for 50 years. Yes, in most cases I do like epoxy primers for metal, but not in this case or with VHT caliper paint. My opinion from my experience.

[Retro Rocket]

I respectfully disagree, and from experience using acetone to clean and prep. I have found some paints or finished that don't work with acetone. I have painted and refinished for 50 years. Yes, in most cases I do like epoxy primers for metal, but not in this case or with VHT caliper paint. My opinion from my experience.

I would like to know which paints {for my own curiosity}, I'm a tradesman painter and use {and specialize}in epoxy paints, we also use just about every type of paint there is, , Poly urethane, 2 pac automotive, even enamel and acryllic paints and house paints and have never had a problem..? Acetone prepwash, prepsol and all the cleaners painters use are 100% hydrocarbon, including thinners.... Once cleaned with acetone or any of the other mentioned products, the part or object being painted should be cleaned dry of any residue anyway.... You would be amazed at some of the things we paint...

[Viktor.J]

is it very cold in your location at the moment?

The place where I sprayed them is around 20C, in my apartment around 20C. And before I sprayed I put the can near a radiator etc. Shaked it well over advertised

The paint you show is pretty thick to have the fingerprint impressions I think...  Some paints react with themselves and trap the outgassing of solvents.  Sometimes you just can't win with some paints...
 

The finger prints is from after the curing, when I was trying to feel the surface and the nature of the "boubbles" so that was after the train left so to speak

I respectfully disagree, and from experience using acetone to clean and prep. I have found some paints or finished that don't work with acetone. I have painted and refinished for 50 years. Yes, in most cases I do like epoxy primers for metal, but not in this case or with VHT caliper paint. My opinion from my experience.

I would like to know which paints {for my own curiosity}, I'm a tradesman painter and use {and specialize}in epoxy paints, we also use just about every type of paint there is, , Poly urethane, 2 pac automotive, even enamel and acryllic paints and house paints and have never had a problem..? Acetone prepwash, prepsol and all the cleaners painters use are 100% hydrocarbon, including thinners.... Once cleaned with acetone or any of the other mentioned products, the part or object being painted should be cleaned dry of any residue anyway.... You would be amazed at some of the things we paint...

Why cleaned of with residue ? the acetone dries of quite fast ? I mean like 15 minutes right ?



To summarize one problem could be the primer ?

[Retro Rocket]

Why cleaned of with residue ? the acetone dries of quite fast ? I mean like 15 minutes right ?

I work in some pretty dirty and toxic environments at times, we did a restoration of a galvanizing plant last year, even after washing down with acetone or similar products i would wipe over with a clean rag, can't be too careful, it may be over kill on bike parts but in that case, I use a tack rag....

[gecko672]

The bubbles look like impurities/oils/gases  coming out of the part itself that cant escape the layers of paint.The high heat second bake is what probably caused this.
The wrinkles look like too many layers of paint that got heated up and softened  in the second bake as well  and started to flow again wrinkling up like paint sags. Probably a few factors that caused this.
Not sure why the paint was soft after the first bake, but it could be that there was just too many layers of paint that couldn't off gas properly. Sounds like you had 6 layers of paint, between primer and topcoat. Maybe the suggestions of no primer are the best, to cut down on the paint thickness.
 just my 2 cents.

[Kickstart]

The bubbles look like impurities/oils/gases  coming out of the part itself that cant escape the layers of paint.The high heat second bake is what probably caused this.
The wrinkles look like too many layers of paint that got heated up and softened  in the second bake as well  and started to flow again wrinkling up like paint sags. Probably a few factors that caused this.
Not sure why the paint was soft after the first bake, but it could be that there was just too many layers of paint that couldn't off gas properly. Sounds like you had 6 layers of paint, between primer and topcoat. Maybe the suggestions of no primer are the best, to cut down on the paint thickness.
 just my 2 cents.

I'm no paint expert, but this explination makes sense to me.  The only time I had bubbles painting with a rattle can was when I put on too many thick coats too quickly... so the off-gassing of one coat was caught beneath the coats apply on top of it.

For what it's worth... I've used VHT paint on one of my calipers, it looked great until I bled the brake.  The paint bubble and pealed around the bleeder valve.  I won't use it again.  I also recommend powder coating them if you can find a place.

[mono]

Bead blast the parts, clean (I use lacquer thinner or Prep-Sol) and do not use primer. Do not put the paint on to thick.

What he said. I have obtained my best results using VHT without primer.
Also, as mentioned above, baking prior to painting can help drive contaminants out of the sometimes porous aluminum.

+1 to that.  I sprayed VHT on my bare aluminum calipers and they came out great.  brake fluid still F'd 'em up, but they looked good at 1st and were hard.  When I paint with spraycans, I try and let the part heat in the sun (or with a space heater) 1st - the paint seems to lay down a bit better.   also make sure your paint isn't cold. 

and +1 on the earlier comment that spraying a 2nd coat after full-cure made it wrinkle.  seems to happen with ALL spray paints I've messed with.  the solvents in the new paint probably swell the dry paint...

[rhinoracer]

I have no experience with VHT paints but what you describe sounds exactly to what happens when you spray a second coat of paint over the first that hasn't cured.

I think the second coat will not let the solvents from the first coat to evaporate and will remain wet for a looong time.

Similar to what happens when you leave a half empty can of paint for several months uncovered. The paint in the surface will dry forming a thick layer that prevents the rest of the paint from drying.

Try a sample piece, spray first coat, let dry for a day, then the second and let dry for a day. I'm almost sure you'll get better results.