35 replies to this topic

[JonnyAlpha]

Hi;

 

I have removed my subframe to complete repairs to the boot floor heelboard ends and sills.  

I'd like to Stone Chip the underside of the boot and wheel arches and need a bit of advice on the process and materials used - tight budget i'm afraid but I don't want to do anything that ill later regret.

 

Iv'e read a few posts and just need to clarify.

 

Once I have completed each bit of welding, after cleaning up to bare metal, I was planning on Etch Priming as I go to prevent any surface rust. 

 

The underside of the car has a small amount of underseal which I will clean off with a heat gun but will I need to remove all the existing paint to bare metal? 

 

What should I prime with, before applying the Stone Chip and I have read about applying a coat of gloss over the Stone Chip any advice on what top coat to use.

 

After the first coat of primer I was also planning on seam sealing.

 

I don't have any spray gear so I may have to consider doing this using rattle cans, I do have access to a small compressor (25Ltr 9.11cfm) would this be alright for the underbody as the finish wont be seen? I have a friend that also has another probably small one so I could probably hook up the two? 

 

As far as products go should get, U-Pol Gravitex or Dinitrol , the U-Pol Gravitex comes in a bottle, found this thread on Stone Chip which seems to recommend U-Pol Gravitex, it appears to be applied with a Shutz Gun and can be applied with a small compressor?

 

Found a few Shutz Guns on Amazon and EBay can anyone point me in the direction of a decent gun and will it attach to these bottles or will it need a can? The description says it can be applied neat or 5% cellulose thinners, can it be applied neat with a Shutz Gun or will it need thinning? 

 

Has anyone used Dinotrol, this comes with a Shutz Gun which needs a compressor, the description states:

• A compressor providing 6 Bar or 90psi operating pressure and 4 CFM (cubic foot per minute) will be required to apply this product.

So my compressor will do the job?

 

Sorry for all the questions.

 

Thanks 

Edited by JonnyAlpha, 06 April 2014 - 07:55 PM.

[Daz1968]

I wire brushed the underside and applied rust remover to be sure, I applied one good coat of David's zinc 182 paint, seam sealed where required then over coated with upol gravitex neat with a shutz gun, I did this with a compressor similar spec to yours, then I applied two coats of 2k direct gloss over the top. Only regret was the David's zinc paint and if I do another would use epoxy based zinc primer. I can 2.5 litres of this for £30 from a local paint supplier. The David's paint caused a bit of cracking in places with the stonechip so I had to rework a few areas it also softened with the seam sealer so care had to be taken when brushing this on.

[tiger99]

You are not going to get the ideal amount of adhesion with any non-epoxy zinc based primer, which is unfortunate, because the anti-corrosion properties of the zinc are desirable. The only way around the adhesion problem involves comprehensive grit blasting, and even then, only with certain grits, to give a surface that will interlock with the primer. Sadly we can't have everything that we might want, for instance a self-etching zinc primer would explode in the tin.

 

An epoxy-based zinc primer is definitely better, although adhesion is still the limiting factor. It is probably what you should use in the circumstances. Roughen the surface up as much as you can, with sanding disks or whatever method is available to you, to attempt to maximise the adhesion.

 

Seam seal after the primer, but you should have used zinc-based weld-through primer in any seams that have been repaired. If not, try to get some into the seams (rattle can will do) before you apply the sealer.

 

Personally, I would want as many coats of primer as are reasonable, depending on the material used, under the stonechip, so the stonechip is only protecting against stones, not playing any part in sealing the metalwork. You may be using a "Schutz Gun" (follow the recommendations of the manufacturers of whatever products you choose EXACTLY) but don't use "Schutz" as such, it is useless junk, with all the same problems as earlier forms of underseal, and was a product really intended for back street "MOT standard" bodgers, not for proper restoration work. Modern stonechip is very, very much better.

[Carlos W]

There's a good guide on the mig welding forum on this topic

[JonnyAlpha]

There's a good guide on the mig welding forum on this topic

Do you mean these? If so I have been reading through them. 

[JonnyAlpha]

Based on what I have identified so far and driven by budget my planned course of action following welding is as follows:

 

1. Zinc Weld Through Primer in seams being welded or internal areas that will remain enclosed.

2. Etch Prime bare metal along the way whilst welding underside and heel board?

3. Remove all remaining underseal.

4. Clean up with wire brush (Twisted Knot Angle Grinder / Drill etc)

5. Apply Anti Rust where required - I'll probably use Hammerite KRUST.Apply Epoxy Based Zinc Primer.

5. Apply Epoxy Primer.

6. Seam Seal.

4. Smooth Seam Sealer with thinners (What type??)

5. Apply additional coat(s) of primer???

6. Apply U-POL Gravitex using Shultz Gun (Model TBC) and my 90Ltr 9.11cfm Compressor.

7. Possibly apply top coats Gloss - any recommendations on type

 

Any recommendations on a cheap but effective spray gun to use for the Epoxy Primer?

Because of my budget and compressor size I have been advised to get a touch up gun.

To avoid having to buy a touch up gun, I can borrow a spray gun but I don't know what make / model so pointers on what it should have would help in case its no good, i.e what controls / spray nozzle / spray shape should it have as a minimum?

Edited by JonnyAlpha, 07 April 2014 - 02:01 PM.

[JonnyAlpha]

P.S. My Seam Sealer is Ever Build Tecnic Pura Flex 40 recommended either on here or Mig Welding?? I believe its a Polyurethane Sealant / Adhesive, any idea what should be used to smooth it in?? On the Mig Welding Seam Sealing tutorial they use Cellulose Thinners? 

[Daz1968]

Have a look on YouTube for setting up a spraygun, there is only pressure, fluid flow and fan pattern/airflow on gun to adjust. You really need to find out what the spraygun is to determine pressure required and cfm useage as some can use 16cfm upwards and most domestic compressors won't keep up. Pressure required for a spraygun vary anything between 29psi and 45psi and incorrect pressure will give a terrible finish. Older tech sprayguns will be less efficient and give more overspray. A Bergen mini hvlp gun off eBay would be a reasonable cheap gun to use

Edited by Daz1968, 07 April 2014 - 07:17 PM.

[JonnyAlpha]

You are not going to get the ideal amount of adhesion with any non-epoxy zinc based primer, which is unfortunate, because the anti-corrosion properties of the zinc are desirable. The only way around the adhesion problem involves comprehensive grit blasting, and even then, only with certain grits, to give a surface that will interlock with the primer. Sadly we can't have everything that we might want, for instance a self-etching zinc primer would explode in the tin.

 

An epoxy-based zinc primer is definitely better, although adhesion is still the limiting factor. It is probably what you should use in the circumstances. Roughen the surface up as much as you can, with sanding disks or whatever method is available to you, to attempt to maximise the adhesion.

 

Seam seal after the primer, but you should have used zinc-based weld-through primer in any seams that have been repaired. If not, try to get some into the seams (rattle can will do) before you apply the sealer.

 

Personally, I would want as many coats of primer as are reasonable, depending on the material used, under the stonechip, so the stonechip is only protecting against stones, not playing any part in sealing the metalwork. You may be using a "Schutz Gun" (follow the recommendations of the manufacturers of whatever products you choose EXACTLY) but don't use "Schutz" as such, it is useless junk, with all the same problems as earlier forms of underseal, and was a product really intended for back street "MOT standard" bodgers, not for proper restoration work. Modern stonechip is very, very much better.

Thanks for the advice, it seems Epoxy is the way to go however just did a quick search for Epoxy Primer and it seems its not generally used by Auto Body Shops, as I am not sure what I'm looking for any tips on what to buy and poss where from (what thinners for cleaning, does the primer need thinning?). Popped into a garage and got a number for there paint supplier and the body repair / paint guy that the garage uses so i'll call them as well.

 

Thanks 

[Daz1968]

I have not used epoxy myself yet, but joton 87 gets a good review on mig welding forum. Depends where you are based but look for industrial or marine paint supplies as it is used a lot on boats. Black Country paints in Wolverhampton are nearest for me but don't limit yourself to autopaint suppliers.

[JonnyAlpha]

Have a look on YouTube for setting up a spraygun, there is only pressure, fluid flow and fan pattern/airflow on gun to adjust. You really need to find out what the spraygun is to determine pressure required and cfm useage as some can use 16cfm upwards and most domestic compressors won't keep up. Pressure required for a spraygun vary anything between 29psi and 45psi and incorrect pressure will give a terrible finish. Older tech sprayguns will be less efficient and give more overspray. A Bergen mini hvlp gun off eBay would be a reasonable cheap gun to use

Like these http://www.ebay.co.u...cat=0&_from=R40

 

I like this one: http://www.ebay.co.u...=item1c3d136994

[Daz1968]

They are all very similar but I would go for a 1mm needle set up rather than 0.8.

[JonnyAlpha]

They are all very similar but I would go for a 1mm needle set up rather than 0.8.

 

This answers a question I just asked in the Mig Welding Forum

Looks like a Bergen touch up gun with a 1mm needle which i'll put up with until I can afford a bigger compressor, thanks. 

[JonnyAlpha]

I have not used epoxy myself yet, but joton 87 gets a good review on mig welding forum. Depends where you are based but look for industrial or marine paint supplies as it is used a lot on boats. Black Country paints in Wolverhampton are nearest for me but don't limit yourself to autopaint suppliers.

Not looked for a local supplier but have found an example of it on the web here that's £50.00 for about 35m2 that's about 6 Minis?? I live on the coast so I'm sure i'll find it locally.

[Carlos W]

 

I have not used epoxy myself yet, but joton 87 gets a good review on mig welding forum. Depends where you are based but look for industrial or marine paint supplies as it is used a lot on boats. Black Country paints in Wolverhampton are nearest for me but don't limit yourself to autopaint suppliers.

Not looked for a local supplier but have found an example of it on the web here that's £50.00 for about 35m2 that's about 6 Minis?? I live on the coast so I'm sure i'll find it locally.

 

 

You need proper safety gear to use it though